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## Solid States Devices => solid state devices => Topic started by: Dark Alchemist on September 27, 2013, 08:35:45 AM

Title: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 08:35:45 AM

That is the simulation I did and I can't figure out how to get it to do more than 28ma at 0.5v (any higher volts makes it go crazy).
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 27, 2013, 02:38:29 PM
The circuit is a Joule Thief variant. I've re-drawn it using a more standard "rail-to-rail" layout so that the JT-ness is more obvious.
Please check my schematic re-draw for errors. I couldn't quite make out the value of the base resistor-- it looked like 400k but please correct me here if I got it wrong.

I am confused about your "28 mA". Please explain what you are talking about here. The JT produces pulses through the LED. The current during the pulse will be a matter of the "turn-on" voltage of the LED and its resistance, or fwd voltage drop, and the supplied peak voltage value from the JT oscillator. I see nothing in your sim or schematic that allows measurement of current here.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 03:45:38 PM
That looks about right except it is 800k resistor not 400k.  He managed to get this to work at .5v but max is 28ma with my mods but a higher voltage, or ma requirement, and forget it.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 27, 2013, 05:44:10 PM
OK, I'll correct the schematic to read 800K for the resistor. thanks.

But I still don't understand this "28 mA" and "higher mA requirement" that you are talking about. Do you mean input current from the 0.5 V source?

Please tell me exactly where this "28 mA" figure is coming from, and what you do to change it to, say, 29 mA that doesn't work.

JTs that are designed for very low input voltages will often "saturate" and stop oscillating if given too much input voltage. That's not so unusual.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 08:41:21 PM
OK, I'll correct the schematic to read 800K for the resistor. thanks.

But I still don't understand this "28 mA" and "higher mA requirement" that you are talking about. Do you mean input current from the 0.5 V source?

Please tell me exactly where this "28 mA" figure is coming from, and what you do to change it to, say, 29 mA that doesn't work.

JTs that are designed for very low input voltages will often "saturate" and stop oscillating if given too much input voltage. That's not so unusual.
The video showed what I meant by 28ma and .7v and 1v I don't consider too much voltage but I think this circuit does.

28 ma LED and that box (sorry I assume people have multisim) you saw me open that is where you can change the If of the LED.  I can change it all the way up to 28ma and it works but at 29ma it no longer will power the LED on.

So, I am wanting a way to increase the circuit's ability to power a LED beyond 28ma.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 27, 2013, 10:56:42 PM
The video showed what I meant by 28ma and .7v and 1v I don't consider too much voltage but I think this circuit does.

Are you talking about where you changed the LED model component parameters from 20 mA to 28 mA?

What that number means is that, at a supplied DC voltage of 3.4 V (or whatever you are putting into the LED parameters), the LED _model_ is designed to draw 20 mA of DC current and produce the rated light output. I don't think this has anything to do with what your circuit is producing. By raising this current value you are essentially lowering the forward voltage of the LED model component, I think.
I have found that higher forward voltages usually work better for light output. In fact, by putting two LEDs in series, one can often get better performance. This is why most JTs use the higher voltage white or blue LEDs rather than red or green ones, I think. Why don't you try _lowering_ this current value in your LED model and see what happens? Or you could try raising the LED model's voltage to 6 volts, keeping the 20 mA current value.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 27, 2013, 11:04:58 PM

The LED will have a published "forward voltage" that describes the voltage needed to put a certain small current through the LED. Above that stated forward voltage the relationship between the supply voltage and the current through the LED will look like the graph below. This is for a red LED with a rated "forward voltage" of about 1.7 V, but your blue LED will have the voltage values higher, but the shape of the curve will be the same. Your simulator model is setting the curve to hit the point at 3.4 V at 20 mA. So when you change the value to 28 or 29 mA, you are essentially moving the curve to the left: the voltage values needed to produce a given current in the LED decrease.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 11:09:03 PM
Are you talking about where you changed the LED model component parameters from 20 mA to 28 mA?

What that number means is that, at a supplied DC voltage of 3.4 V (or whatever you are putting into the LED parameters), the LED _model_ is designed to draw 20 mA of DC current and produce the rated light output. I don't think this has anything to do with what your circuit is producing. By raising this current value you are essentially lowering the forward voltage of the LED model component, I think.
I have found that higher forward voltages usually work better for light output. In fact, by putting two LEDs in series, one can often get better performance. This is why most JTs use the higher voltage white or blue LEDs rather than red or green ones, I think. Why don't you try _lowering_ this current value in your LED model and see what happens? Or you could try raising the LED model's voltage to 6 volts, keeping the 20 mA current value.
I started it at 5ma it worked even better and there is no way to change the foward voltage in multisim.  I could try to make a brand new model but I tried that a few days ago to a dismal failure.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 11:10:32 PM
The LED will have a published "forward voltage" that describes the voltage needed to put a certain small current through the LED. Above that stated forward voltage the relationship between the supply voltage and the current through the LED will look like the graph below. This is for a red LED with a rated "forward voltage" of about 1.7 V, but your blue LED will have the voltage values higher, but the shape of the curve will be the same. Your simulator model is setting the curve to hit the point at 3.4 V at 20 mA. So when you change the value to 28 or 29 mA, you are essentially moving the curve to the left: the voltage values needed to produce a given current in the LED decrease.
As I said it works from 1ma all the way to 28ma but not beyond with the Blue LED (3.45v)
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 27, 2013, 11:17:52 PM
I started it at 5ma it worked even better and there is no way to change the foward voltage in multisim.  I could try to make a brand new model but I tried that a few days ago to a dismal failure.
Well, there you go then, this confirms what I said. Lowering this current value effectively moves the graph to the right, in other words raises the forward voltage.
Don't make a new model, just put 2 or 3 LEDs in series in your sim circuit, this will effectively raise the forward voltage. Think of it like raising the height of a dam. The blocking oscillator needs to have a voltage swing, and when your LED turns on and passes current this limits or clips the voltage level of the swing. If you put two in series you are raising the height of the "dam" so that the voltage swing when the dam overflows is greater, and contains more power.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 27, 2013, 11:22:37 PM
Well, there you go then, this confirms what I said. Lowering this current value effectively moves the graph to the right, in other words raises the forward voltage.
Don't make a new model, just put 2 or 3 LEDs in series in your sim circuit, this will effectively raise the forward voltage. Think of it like raising the height of a dam. The blocking oscillator needs to have a voltage swing, and when your LED turns on and passes current this limits or clips the voltage level of the swing. If you put two in series you are raising the height of the "dam" so that the voltage swing when the dam overflows is greater, and contains more power.
Am I only looking to see if it lights all of them up?  I was hoping to put a 300ma and/or a 700ma bright white LED in the real circuit but I need it to simulate that first.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 12:02:32 AM

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 12:53:02 AM
I am up to 4 LED and 670pF.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 03:39:13 AM
Good for you. Now you are making higher voltages with your circuit, and you should be seeing more total light output.

I can't quite make out the scope trace in the video. It looks to me like your timebase is set to 1 millisecond per division, is that right?

I'd like to see the scope display the actual signal, three or four peaks across the screen, instead of the "comb" you are showing. Try changing the timebase to 0.1 ms or even 1 us per division. We should also look at the voltage signal directly at the base of the transistor on the other channel of the scope. The max rated Vebo for your BC337 is only 5 volts.

I hope you realize what I was saying about the LED current/voltage relationship. To see what the _actual_ current is that you are putting into your LED stack, you can put a 1R resistor in series with the LEDs/capacitor at the cathode end, and look at the voltage drop across this resistor with one of the scope channels. By Ohm's Law, the current in this resistor is I == V/R, and since R is 1, the current in amps will be equal to the voltage drop in volts that you see on this resistor.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 04:01:03 AM
Consider what a "300 mA" LED means. This means that you take the LED, and a DC voltage source that is comfortably above the fwd voltage of the LED, and you use a current-limiting resistor to limit the current through the LED to 300 mA, and then you get your rated light intensity output from that LED. The average current the LED draws will depend on the average voltage you supply to it! It will _not_ always be 300 mA!

A typical 1 Watt LED (300 mA) has a fwd voltage of 3.4 volts or so. The problem is that your circuit cannot supply 300 mA at over 3.4 volts for any length of time, so the LED won't reach its full brightness during the brief flashes that the oscillator is sending it.
If I had one of these 300 mA LEDs I would not hesitate to try it in the circuit. It's not going to draw an average of 300 mA, though!
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 04:25:27 AM
It might be possible to use a "current probe" in your simulator, instead of looking at the voltage drop across a 1R, to see the current in the LEDs. Sorry I didn't think of this before.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 05:50:56 AM
Good for you. Now you are making higher voltages with your circuit, and you should be seeing more total light output.

I can't quite make out the scope trace in the video. It looks to me like your timebase is set to 1 millisecond per division, is that right?

I'd like to see the scope display the actual signal, three or four peaks across the screen, instead of the "comb" you are showing. Try changing the timebase to 0.1 ms or even 1 us per division. We should also look at the voltage signal directly at the base of the transistor on the other channel of the scope. The max rated Vebo for your BC337 is only 5 volts.

I hope you realize what I was saying about the LED current/voltage relationship. To see what the _actual_ current is that you are putting into your LED stack, you can put a 1R resistor in series with the LEDs/capacitor at the cathode end, and look at the voltage drop across this resistor with one of the scope channels. By Ohm's Law, the current in this resistor is I == V/R, and since R is 1, the current in amps will be equal to the voltage drop in volts that you see on this resistor.
Yep, I am familiar with the 1Ohm measuring technique but then I read it isn't that simple.

The resolution (gotta love how Youtube takes a perfectly clear 1280x1024 video and rapes it even for HD) of the time base is 1ms/div but at 1us a division I can't see what it is doing as it is too fast (I think this is a shortcoming of the scope in Multisim as it has no persistence at all and being digital what they are doing is clearing the screen of the scope each time the dot hits the end and retracing from the beginning which, at fast times, is really useless for real time work.

Scope is set X axis - 1ms/div and Y axis - 1v/div
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 06:05:54 AM
It might be possible to use a "current probe" in your simulator, instead of looking at the voltage drop across a 1R, to see the current in the LEDs. Sorry I didn't think of this before.
I did use that in my previous JT that I posted about here (I think it was here) and people said not to trust those readings due to all sorts of issues.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 06:15:38 AM
Well... I can't help you with your Multisim... I run a Linux system and I can't find any way to run it even under Wine. And it's not free either. But that doesn't sound like a normal, or useful, simscope behaviour to me. With a regular signal you should be able to display a regular, interpretable trace.

Let's see. JTs usually run at a fairly high frequency range, like 15-50 kHz or so. 20 kHz is a typical rate. So at 20 kHz,  in 1 ms, you would expect to see 20 peaks across one single division on the scope. Right? IOW, an uninterpretable comb like you showed in the video.

At 1 microsecond, there wouldn't be enough time for a complete period of a 20 kHz signal. Right? As you describe. The period is the inverse of the frequency, so the period is 1/20000 = 50 microseconds. Right?

So 1 ms is too slow, 1 us is too fast. Try 0.1 ms (100 us) per division. If the JT is running at 20 kHz you should see two peaks per division. Try 10 us per division, then you should see two peaks across 10 divisions... an ideal display of a 20 kHz signal.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 06:16:13 AM
I did use that in my previous JT that I posted about here (I think it was here) and people said not to trust those readings due to all sorts of issues.

What were the issues? Who were the people?

ETA: Now that you have your voltage pumping up a little bit by using series LEDs, you can start adding parallel groups of LEDs for possibly more light output. Try three in series, parallel with three more in series, along with whatever parallel cap value you need.
Here's a video of a 1:1 JT like yours, running 24 LEDs in a 12-parallel, 2-series arrangement, running on a depleted AAA battery. This JT will light a single LED to good brightness... but it lights the full array much better.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 06:22:05 AM
What were the issues? Who were the people?
A real Joule Thief operates off a single 1.5-volt battery and has one or more LEDs as the load.  Because of it's somewhat unusual operating characteristics and the fact that LEDs complicate the output power measurement because they are what is called non-linear electrical devices it's actually much more complicated and difficult than you think.

The real way to do it would be with a digital storage oscilloscope.  Preferably you would have one with a built-in math function.  You have to measure the instantaneous voltage and current output by the battery, as well as measuring the instantaneous voltage and current across the LED.

It just happens to be a circuit where multimeters and a basic scope will not cut it and you can't really make the power measurement unless you have the right equipment and you really know what you are doing.

MileHigh
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 06:38:29 AM

Well, MH is right, but that's not a fatal issue! Don't let him scare you away from doing the analysis properly. It's not complicated, just tedious. Your MultiSim will surely do the required stuff as far as simulating the DSO's storage and math capability. And I've demonstrated several times how to do it all using analog scopes, screenshots and spreadsheets.

The current probe, once the scope is set properly, will give you the instantaneous current waveform through the measurement point, and you already have the voltage measurement in the other channel. I would be very surprised if the software could not multiply those together point-by-point and then integrate the resulting instantaneous power curve over the time of the measurement. Or you can ask the scope to give you the "average" value of the current, if that's all you are looking for. The peak current can be read directly from the traces once you have the scope set to display the signal properly.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 06:49:16 AM
Well, I must be doing something wrong because as soon as I hook up a 1ohm resistor it will never start up.  I tried it in series from ground to the last LED's cathode and I tried it from ground to the anode of the first LED and no go with either.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 07:59:30 AM
Here is a screen capture of a moment in time with my settings which are: X - 1us/div, Y - 1V/div ch1, Y - 2mV/div ch2 R2 - .1ohm

I am seeing negative current it seems but if my math is correct I am seeing 2.3mv/.1oh, = +/- 23ma or is my calculation faulty?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 05:26:28 PM
Here is a screen capture of a moment in time with my settings which are: X - 1us/div, Y - 1V/div ch1, Y - 2mV/div ch2 R2 - .1ohm

Oh, have mercy! It's really hard to make out the scope screen from here, at the size/resolution you are posting. But I can see a couple of things. The blue Current signal isn't like any JT signal I've seen, it's more of a symmetrical sinusoid instead of the regular more-or-less rectangular pulses or spikes I generally see. But at least we can tell the frequency. You have just over 30 peaks in 8 microseconds.. .call it 30.1 cycles per 0.000008 sec, or around 3.76 MHz, which seems really high to me. And I can't see any corresponding peaks in the red Voltage trace, so I'm wondering if you've actually captured the true JT oscillation here or are seeing some other noise source.
When using a very small CurrentViewingResistor (CVR or CSR) it's easy to pick up noise. Since your system won't oscillate with a 1R in there (also a bit strange) I would try eliminating the resistor and the voltage-current conversion completely by using a pure "current probe" there if your sim allows it.
Quote

I am seeing negative current it seems but if my math is correct I am seeing 2.3mv/.1oh, = +/- 23ma or is my calculation faulty?
Well, as I said before I'm not sure if you are really seeing the current signal yet. But what I see on the Blue trace is 1 full division plus about 1/3 or 2/5 more, so that would be just under 3 mV (1 1/2 divisions would be 3 mV). And the same on the negative side. Your math is correct but you are reading the trace incorrectly, at least from my blurry view here.
However, your scope has cursors that you can position. The numbers and arrow buttons in the T1 T2 box "time Channel A Channel B" at the top left of the parameters area appear to be the cursor positioning and values section. So you can read the exact voltage peaks by using the cursors and reading the values you get here.

Also, at the bottom right of the screen are the scope's Trigger controls. Please set this at "Auto" or "Normal" and a level of about + 0.25 volts, ascending slope,  and use the Red channel, the Channel A, as you are using. What happens to the trace when you do this?

The JT I showed in the video above has a 1:1 transformer (actually 13 : 13 turns) and each winding has an inductance of 388-390 microHenry, measured on my ProsKit RCL meter and confirmed by my Arduino-based L meter. I can't tell what the coupling coefficient is but it's probably in the range you are using, 0.5-0.8, since it's a good ferrite.   It certainly doesn't oscillate at 3.7 MHz, though!

I might be able to modify this unit to "simulate" your simulation results in hardware by changing the cap values and etc. Let me see what I can arrange, and I'll give you some news later this afternoon.

But meanwhile, see if you can try the trigger setting I recommend, along with using the scope cursors to get precise voltage values from the traces. Also, if the 0.1 R CVR is causing noise pickup, eliminate it and use a "current" probe in the same position, if your sim allows.

I would apply the changes in this order: First, the current probe. See if your signal still looks the same. Then apply the trigger settings I suggest. The signal might disappear! If it does then try changing the timebase to 10 or 100 microseconds per division and see if the signal comes back stably on screen. If the signal doesn't disappear when you set the trigger as I have suggested but remains looking like it does now... then I'll have to play around with hardware myself to see what is up.

Bottom line: since I'm not seeing the characteristic JT-like peaks on the Red trace, and your Blue trace is so symmetrical and so high frequency, I am not confident that we are seeing the actual JT performance on the scope yet.

I've attached an example scopeshot from one of LTseung's JTs. Top trace corresponds to your Ch A probe point and bottom trace to your Ch B. The values you get will be different of course - especially the spikes/pulses should be narrower -- but the basic shape of the signals should be similar, I think. The symmetrical sinusoid of your Blue trace is atypical and I'll have to reproduce it in order to understand it fully.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 05:44:42 PM
Another thing: Looking at the specs for the BC337 and comparing to the 2n2222 I don't see much difference except in the voltage handling ability. What happens when you take the exact circuit you show above, with scope settings exactly as you have there, if you change the transistor to a 2n2222, or a 2n2369a, or MPSA18, my personal low-voltage favorite?

I'm asking because I don't have a BC337 on hand, and am not likely to be able to get one.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 05:52:39 PM
Another thing: Looking at the specs for the BC337 and comparing to the 2n2222 I don't see much difference except in the voltage handling ability. What happens when you take the exact circuit you show above, with scope settings exactly as you have there, if you change the transistor to a 2n2222, or a 2n2369a, or MPSA18, my personal low-voltage favorite?

I'm asking because I don't have a BC337 on hand, and am not likely to be able to get one.
I literally have a crap load of BC337, lol.  Let me run the sim with a 2n2222 using my changes as Lidmotor's original design would not oscillate.

As far as a current probe in the sim I do not have that but I do have a probe that just spits numbers at you but someone mentioned that wouldn't tell me anything.

Nope, the 2n2222, 2n2369a, or the MPSA18 will oscillate.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 06:05:54 PM
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 07:21:59 PM
OK, so by setting the trigger as I suggested, the Blue trace vanished? You made no other changes, just setting the trigger?

Now try changing the timebase to 10 or 50 microseconds per division, making no other changes.

In your last post you said,
Quote
Nope, the 2n2222, 2n2369a, or the MPSA18 will oscillate.
So I'm confused again. The "nope" part doesn't seem to agree with the "will oscillate" part. Did you mean that "neither" will oscillate, or that they "will not oscillate" or what?
If they _do_ oscillate could you please post a scopeshot using one of them? If they don't oscillate, never mind, just please try the timebase change I suggested above.

ETA: Wait I see you have the "Blue" channel disconnected. Please go step-by-step. Replace your 0.1 ohm resistor, use the Blue channel to monitor the voltage just as you had in your previous shot. Change ONLY the trigger setting, to +0.25V on the Red channel, set to "auto" or "normal".  Then show the screenshot.
Then, change the timebase from 1 us/div to 10 or 50 us/div and show the screenshot. Please only change one thing at a time, because I confuse easily.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 28, 2013, 07:38:09 PM
I just checked the JT I showed in the video above. It oscillates at about 14.6 kHz, much much slower than the 3.76 MHz of the Blue trace you showed above. I'm not convinced that your Blue trace really is showing the main JT oscillation of your circuit, nor is the Red trace in your latest scopeshot.

Try this: using the exact setup you have just above, with only the Red Channel A Q1 collector signal shown. Set the trigger on Ch A, rising slope, +0.25 volts, "Auto" or "normal". Now change the timebase in steps. You are showing 1 us/div already, so now look at the signal at 10 us/div, 50 us/div, and 100 us/div, or whatever similar settings your scope allows.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 10:15:24 PM
1us
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 10:15:41 PM
10us
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 10:15:56 PM
50us
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 28, 2013, 10:16:10 PM
100us
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 01:42:28 AM
Weird. Thanks for doing that, even though it leaves me a bit more confused about what is going on.
The _average_ value of that oscillation is at your 0.5 volt supply voltage, and the peaks never seem to go high enough to overcome the LED's forward voltage. So this signal could not be lighting up the LEDs, especially not 4 in series.

Could you please try this now: Set your trigger voltage to some value decently _above_ the peaks shown in the traces above. Try setting the trigger to +2.0 V, and the timebase back to 1 millisecond per division, and wait a bit to see if anything shows up.  What I am thinking is that perhaps your circuit is oscillating in bursts and we are missing the voltage peak that lights the LEDs.

I've rewired my JT testbed to correspond to the circuit in your schematic, except that my inductance is still a bit low and I don't have the right transistor. But with 2n2222 I get this: the circuit flashes both the single LED or the 24-LED 2series-12parallel array at about 1 per second. The flashes are fairly dim. If I use the MPSA18 the flash rate increases to perhaps 2 per second. I've got a bunch of low-voltage "dead" batteries and I found one that indicates 0.7 V open-circuit, and this battery powers the circuit fine, but another one with under 0.4 volts won't. I don't have an easy way to provide a precise 0.5 volts supply at the moment, but later on tonight I'll try to make one.

Now, I've just used the "single shot" capability of my Link DSO to capture the waveform of a single flash. It's pretty interesting.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 02:02:11 AM
I've made a video of what I'm talking about, but it will be a few minutes before it's processed and uploaded. Check this space in a few minutes for the link.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 02:05:38 AM
I think something is seriously wrong with Spice as I did what you said and set it to single and 2.0V trigger level.  Nothing happened then I got a big burst and nothing but as the nothing was happening after that burst my LEDs were flashing.

The burst is almost 1000us long then nothing but the LEDs are flashing.  So, that means the voltage never goes over 2 volts to trigger the scope but those 3.45v LEDs are all flashing.

So, what gives, or basically WaTaF is going on with this simulation?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 02:29:13 AM
I think something is seriously wrong with Spice as I did what you said and set it to single and 2.0V trigger level.  Nothing happened then I got a big burst and nothing but as the nothing was happening after that burst my LEDs were flashing.

What gives?

Nothing is wrong, your circuit is doing just exactly what I thought, and mine is doing the same thing, I think. I'm uploading a video explanation right now, showing how to catch the oscillation bursts. It should be up in half an hour or so, my upload connection is really slow.

http://youtu.be/9FDmkbCbKP0 (http://youtu.be/9FDmkbCbKP0)

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 02:34:43 AM
I think something is seriously wrong with Spice as I did what you said and set it to single and 2.0V trigger level.  Nothing happened then I got a big burst and nothing but as the nothing was happening after that burst my LEDs were flashing.

The burst is almost 1000us long then nothing but the LEDs are flashing.  So, that means the voltage never goes over 2 volts to trigger the scope but those 3.45v LEDs are all flashing.

So, what gives, or basically WaTaF is going on with this simulation?

Sorry, we crossed posts there. The Single Shot mode does one sweep after it's triggered, then you have to restart or repress Single Shot for another triggered sweep. So you captured a single sweep, probably, and then the scope stopped. Your circuit is still running and for sure there must be spikes in there that exceed the combined fwd voltage of the LED string, or they would not light.
It might be clearer when you watch my video. I _think_ I've captured the behaviour, but since I'm using a different transistor I can't yet be sure, until we are both showing similar scopeshots. We do seem to be making some progress, though!
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 02:46:52 AM
I will watch it once it is up but what I did was set it to single shot 3.4V (LEDs are 3.45v) and it never ever triggered BUT the LEDs were flashing like mad.

It triggers at a max of 2.25V
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 03:02:45 AM
Weird.
Anyhow, the video is ready now.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on September 29, 2013, 03:03:28 AM
I decided to unify my old account and make this account since Youtube knows me as someone else (this name) and Dark Alchemist was taken over there.

I figure I will be doing a lot of work like this and need to have the names of both places the same.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 03:05:58 AM
I just posted under my new account here of the name I go by on Youtube.  This name was taken over there so I had to use something else.  I figure I need the same name here and there since I plan on doing a lot of work with this stuff and my 20mhz scope was shipped today (100mhz DSO will be sometime next year Rigol 1152E I think).

My new post is above this one but needs moderator approval before it shows.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 03:21:53 AM
Here is a weird oddity and that is at 0.5V max trigger is 2.25V at 1.4V it becomes 6.715V
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 05:12:23 AM
Well, is my circuit behaving like yours yet? Were you able to get similar scopeshots of the bursts to what I was getting?

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 05:23:36 AM
Not exactly like yours but I do get bursts at the trigger levels and voltages I said.  No way 2.45v is lighting 4 blue LEDs in series of 3.45V @20ma each though so I am pretty disgusted at Multisim right now.  From everything I have read it is not something that I am not doing, or forgetting to do, that is causing this.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 06:24:35 AM
Here is something I found and you tell me - www.youtube.com/watch?v=EARtlFx0gpk
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on September 29, 2013, 04:49:22 PM
2us a div and showing the .1 ohm resistor.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on September 29, 2013, 04:49:48 PM
500ns/div
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 04:54:27 PM
2us/div showing the circuit as well.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 04:54:50 PM
500ns/div to zoom in on it.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 29, 2013, 06:12:20 PM
OK, so now you have changed the 800K resistor for one of much lower value, and you are getting much more conventional JT behaviour from the circuit. I presume it no longer does the "burst mode" but rather is lighting the LEDs continuously now?

The 500 ns shot shows clearly: the Ch A voltage rises to the combined fwd voltage of the 4 LEDs, which is around 13.5 or 14 volts. Then the LEDs begin conducting, the Ch B voltage (current) rises quickly to its peak value. Then the voltage drops when the system saturates and the current goes back to zero.
The peak voltage on the "current" trace is about 20 mV. So by Ohm's Law the peak current in this 0.1 ohm resistor is 0.020/0.1 == 200 mA. The LEDs are probably pretty bright. The voltage is pretty level at about 14 V during the ON time of the LEDs so your instantaneous power is around 2.8 Watts.
The duty cycle looks to be about 4 or 5 percent HI. So the average power is around 140 mW or about 35 mW per LED. If the LEDs are 20 mA, 3.45 VDC LEDs then they should be drawing twice that with DC power, or 69 mW each, or 0.276 Watts for all 4.
(3.45 x 4) x 0.020 == 0.276 Watts

So... is the stack of 4 LEDs powered by this JT as perceptually bright as they would be, if they were powered by straight DC at 69 mW each? That's the practical efficiency question. Is the output electrical power lower than or higher than the input power? That's the "overunity" question.

I think. It's early though and I may be suffering from a coffee deficiency.

There is one problem though. The 1.2 nF capacitor across the LEDs is part of the load, but your current measurement resistor is inside this loop, so the cap may provide a bypass of some current that isn't going through the 0.1 ohm CVR. You really should put the CVR outside the cap-LED loop (Move the bottom cap connection from the ground up to the other side of the CVR where the probe is). Will it still oscillate that way? I don't see why it wouldn't.  Is this cap really necessary? In my hardware build it doesn't seem to do much.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 10:48:14 PM
Without the cap, and the cap value must change depending on how many LEDs there are, it will not oscillate.

By the way when I remove a LED both curves do change so it is following at least somewhat properly but can I can't get more than about 250ma out of this circuit.

Here is a screenshot with the resistor outside of both the LEDs and the capacitor and now we seem to have a huge negative spike on ch. b.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 29, 2013, 11:34:25 PM
I can't seem to get rid of that huge negative current spike.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 04:18:53 AM
Well, I'm still trying to get the proper component values in my construction. I wound a toroid today with the right inductance, anyway, and tomorrow I'll check with my supplier to see if I can locate a BC337 transistor.
But now, with this new toroid, I get two modes of operation. One is the true JT mode at around 60 kHz and the other is ... weird. Dimmer lights and much lower frequency and a different waveshape. To get the true JT oscs I do need the 1.2 nF capacitor; if I remove it it shifts to the other mode. To get the true JT mode I have to do something to the battery connections, introduce noise or something, I'm not quite sure what I'm doing to get it.

I'll make a video later on this evening. But here's the toroid inductor, measuring one winding. The other is the same.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 04:25:12 AM
You have to admit this monster is a new beast we need to tame.
What is causing the HUGE negative spikes I last saw?

Since I am going to work with coils and such, and I do not have a waveform generator, I think I will purchase one of these:
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 06:31:48 AM
Yes, an RCL meter is very handy. I use the ProsKit, and I also made a neat L meter using Arduino. It's good to have a couple different checks, just to remain sane.

Meanwhile:   All but the "proper" BC337 transistor. But it works great with the MPSA18. Now I seem to be able to get three modes: first startup, without 1.2 nF cap,  is moderately bright, then when I connect the cap it gets brighter, then when I _disconnect_ the cap it gets brighter still !
I haven't scoped this version yet. Here it's running on a tiny AG4 - LR626 button cell, has been for half an hour or so. It's starting to dim a bit now.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 06:48:35 AM
Very nice and what I am trying to figure out is why it gets brighter after you remove the 1.2nf cap?  I added it to get it to run and it ran brighter in the simulator but removing it made it even brighter than both?  That seems so odd to me that stepping it like that made it brighter.  I just wish I knew how much it was putting out and how much it is sucking away for all three modes.

I am torn between that LCR meter that has a screen and the connections and buying an Arduino mega 2560 with no screen but I can update it when needed.  The fun thing about the one I linked is that it tells you what the ESR of caps is and what Transistor you just put in it.  I really want the Arduino but the all in one already built is nice and basically they cost the same.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 07:59:24 AM
The neat thing about the Arduino is that it can be used for so many different applications. And once you get a sketch running doing something you like, like the Inductance meter, you can put the sketch into a Pro Mini, which costs about 4 dollars from Singapore, for a permanent installation.
I use the Parallax brand 2x16 LCD display, which is very simple to use and has a backlight and a miniature speaker, and the Arduino Uno is powerful enough for most all I do. I do have a Mega but the only project I use it for is the 4x4x4 LED cube display.

Here's a demo of my Arduino inductance meter, showing on the scope how it does its thing:
I found a usable comparator chip in an old TV circuit board.

I use the LCD/Arduino for all kinds of things. It makes a good optical tachometer by adding a IR sensor and LED, and I made a Sous Vide temperature controlled crockpot with it too. My most recent Arduino project is a 12-LED color organ with realtime software FFT, but that doesn't use the LCD.

The meter you are getting sounds pretty neat, with more specialized functions. I don't know how I'd implement those in an Arduino sketch. I'm no Arduino expert but I love the little things, they are very useful to make gadgets with.

The negative current spike you are getting... I dunno. Maybe that's the Free Energy leaking in!
My current traces are pretty different from yours, both with the cap in the loop and out of it. I'm using the depleted batteries for power though, so they may not be sourcing enough current, compared to your sim's battery model. I'm going to try using a low voltage regulated supply to see if my current traces can look more like yours.

The differences in brightness are because the thing is shifting frequencies between several stable modes. Why it does this, I don't know, but so far I can tell that the power supply voltage and impedance is a factor. I managed to observe two modes on the scope but unfortunately I didn't video them, and I don't think I'll be able to get to it tonight. They are very different looking and very different frequency.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 09:01:18 AM
The reason of the Mega 2560 is I can get a 2013 SainSmart with the USB cable delivered for \$17.99 and I still can't touch the UNO for that.  SainSmart Mega2560 R3 ATmega2560-16AU + ATMEGA16U2 + USB Cable For Arduino 2013  http://www.ebay.com/itm/271187169712?ss

Yes, the voltage does play a HUGE factor with what you get on the scope even in the simulation.

Now, here is a screenshot of what all I can put in for the battery.  The other tabs for this item play no role.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 02:21:03 PM
Wow...thanks for the link to that Arduino store. How can they sell stuff for so cheap? It's amazing. I might have to place an order there myself, those "starter packages" have a lot of useful items in them. It looks like you could put together an inductance meter equivalent to the one I showed above for under 25 dollars (the Mega and the 2-line LCD). Those LCDs are not as easy to use as the Parallax one I used, though, I don't think. You need several data lines, whereas the Parallax just uses a single serial data line, so only three wires to deal with and no soldering. But it also cost about 10 times more than the ones your link offers.

I don't understand any of that stuff in your "battery" config menu except for the DC voltage and the tolerance! I was hoping to see items like "internal impedance" or stuff like that. Is there some other choice of DC supply instead of a battery, I wonder? Like "voltage regulated DC" or "constant current (really current-limited) DC supply" or such like?
I mean, an ideal battery will provide whatever current the load will demand without sagging in voltage at all. So if you have a zero resistance short you get infinite current at the rated voltage. Of course real batteries don't behave like this because they act like a voltage source in series with a small resistor, so the max current is limited and the voltage will sag as the limit is approached.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 02:49:53 PM
Yeah, their prices are Crazy Eddie time (flash back, lol).

See the Paralax is a serial version and these guys sell parallel versions and price versus number of I/O lines required.  On the Mega you have enough lines to do it and have enough left over but on an UNO you would be hurting so most go the 3 line serial route.

I have a Halloween project I might do and that Ping sensor is only a \$1.85 delivered.  Insane.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 02:56:59 PM
BOOM, lookee there.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 07:57:18 PM
Wow, there you go. You could probably simulate a depleted battery by raising the internal resistance a hair and lowering the amp-hour capacity. Since the capacity is adjustable I'll bet the model includes a "discharge curve" of terminal voltage vs. percent charge or something like that. You probably can't see this internal curve but by setting the two variables in that screen you will be adjusting it.

So you could compare the behaviour of the system using the non-ideal battery with a bit more internal resistance and a very low A-H capacity, if the sim will allow you to set it that low. Compare the waveforms you get, with those you get using the "DC power supply" which is probably a voltage-regulated supply that won't sag like a battery will.

I've just made another little video showing that the thing oscillates even when the voltage is too low to light the LEDs, and what happens when you make and break the connection to the 1.2 nF cap in that low-voltage condition. Also I use a radio tuned to the frequency range it is making and you can actually hear the frequency sweep as it changes modes.

It will be a few minutes before the upload is done.
http://youtu.be/4tMwntAO_cI

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on September 30, 2013, 08:56:16 PM
Heh.... I thought I was all done with Joule Theifs for a while. I have them scattered all over the lab, there must be six or eight of them lurking around. But now I've gone and discovered a new (to me anyway) effect using this one.

The tiny button cell I used in the video above seems to be able to work as a heat-to-electricity converter.

I did something that you should never do: I soldered wires directly to the cell. The battery can explode from overheating if it gets too hot... so wear safety glasses and keep the children (and parents) well away. And since I have this isolated soldering station, I work on live circuits..... and so I found that heating up the battery by soldering on it causes it to put out plenty of voltage to light up the LEDs for a few seconds, then they dim out. Apparently this process can be repeated over and over.

I'm so startled by this that I had to record it on video. The vid is a bit longer and it's uploading now but it will be a while before it appears.
http://youtu.be/K7msKzlNzKw (http://youtu.be/K7msKzlNzKw)
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on September 30, 2013, 10:49:31 PM
How do I know what to put in that box to simulate a real battery?  I have no idea the internal resistance of a battery but if I remember right Dave Jones had that about his 9 volt batteries and that info is hard to find.  So, finding it for a 1.2V 800mah NiMH is probably going to be hard.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 01, 2013, 01:31:25 AM
http://data.energizer.com/PDFs/BatteryIR.pdf
http://data.energizer.com/PDFs/nickelmetalhydride_appman.pdf

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 01, 2013, 01:33:52 AM
I made a printed circuit board for the DALM thing, just to neaten it up. I left out the 1.2 nF capacitor though. My supplier can't get BC337 so I used a socket and the MPSA18, but can change to whatever is necessary for testing.

http://youtu.be/jUraFI3sTYE
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Dark Alchemist on October 01, 2013, 03:41:46 AM
Very nice indeed.

Oh, you forgot to make a video showing the three states you mentioned earlier as that would be interesting to see.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 01, 2013, 06:00:31 PM
I agree.... two states are shown in the RF video, but below the level of lighting the LEDs. Now that I've put it all on the PCB and put in a fresh battery, I got another surprising mode shift: At first the lights were moderately bright, then after half an hour or so I was trying different transistors (none work as well as MPSA18) then when I changed back to the MPSA I was putting it in the socket and was able to kick it into the brilliant mode, with much brighter LEDs. I didn't have the scope hooked up.... and I don't know if I can reproduce this, but I'll try.

Meanwhile, if anyone is interested, here's the layout of the tiny PCB that I designed and etched. This is before etching. You can see how crude it is, with the traces just drawn on with an ordinary Sharpie marker. (I had to add a couple of holes and traces on the image that weren't there when I took the photos, like for the 100 uF cap which I decided to put on the board.)
I did the surface topside layout first, then I drilled the #60 holes, then I sketched in the traces on the copper side "connecting the dots". Warm Ferric Chloride etchant, about 10 minutes of agitation in a plastic tub, cleanup with water and acetone, and Bob's yer uncle.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 01, 2013, 06:45:55 PM
By the way... the silly thing is _still oscillating_ although the LEDs have long gone out. The battery voltage (cheap AG3/LR41) is indicating 0.340 V and the peaks of the collector waveform are at about 1500 mV, and a frequency of 522 kHz. The duty cycle has increased to about 20-25 percent HI.

EDIT: Sorry about that... it's 0.340 VOLTS or 340 mV.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 01, 2013, 06:48:58 PM
;D  Now if we could only tap into those oscillations to do something with.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 01, 2013, 09:48:05 PM
Hmmm..... Still oscillating......
Collector peaks 1540 mV, frequency 520 kHz, duty cycle 18 -20 percent HI....
battery voltage 0.341 V ..........

EDIT: Sorry, I meant VOLTS, 0.341 V not mV. My bad, not enough coffee....

Too bad the LEDs aren't lit. The only "output" is some very weak RF, and there must be a tiny bit of dissipation in the resistor, capacitor and transistor.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 01, 2013, 11:56:11 PM
Man, I need the rest of my tools so I can breadboard up the thing so I can see what you are seeing.  I have all of the parts just not the inductance meter and probably will not have for a month.  Once I get everything I need to see what can be done with those oscillations.  If you want to continue on with the research please do because, as I said, I am hog tied at the moment.

My biggest question about this is what would happen with the 1.2nf cap if it were still in it?  Don't touch it and lets see how much longer she runs but with the removal of the cap I am unsure what that did if for better or for worse.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 02, 2013, 12:25:16 AM
Just grab a toroid or ferrite bar and wind 20+20 turns on it. You might not get exactly 520 mH but you will at least get something that you can fool around with while you wait for your meter to arrive.

It's still oscillating.
Collector peaks 1520 mV, 502 kHz, 19 percent HI
Battery voltage back down to 0.340 V. (Measured with the Simpson 464 DMM, pretty accurate)

EDIT: I had "mV" here, of course it's Volts, 340 milliVolts or 0.340 V.

How I found the right winding: I had that toroid, wound with some 22 gauge magnet wire, but it measured over a milliHenry. So I unwound it, measured the wire length, and then rewound it, and measured its inductance turn-by-turn by scraping off bits of the enamel so I could get a contact with the meter probe clips. Then when I had the right inductance I took the wire back off the toroid, measured the same length of the green plastic insulated #22 solid, doubled it, and wound the two windings at the same time onto the toroid. I had to trim an inch or so at the end of the process to get to exactly 520 uH per winding -- and it turned out to be 20 turns each winding, and they filled the toroid's inner diameter exactly. Coincidence?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 02, 2013, 12:40:35 AM
And I see you got your registration issue settled. Great!

I hope you don't mind if I still call it the DALM thing, though.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 02, 2013, 01:41:37 AM
Still oscillating... collector peaks 1560-1580 mV at 490 kHz, 18 percent HI, battery voltage still 0.340 V.
Interestingly, the scope reports the "average" collector voltage as 340-350 mV.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 02, 2013, 01:50:26 AM
IMPORTANT NOTICE:
I mistakenly had "0.340 mV" when I should have had 0.340 V, or 340 mV. I went back and corrected the earlier posts.... sorry if I had anyone all excited. Please calm down, if you thought I was running something on under a millivolt. Not yet! It's holding steady at 0.340 V, or 340 mV, which in itself is rather amazing. I'm starting to think it might be picking up some power from somewhere else.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 02, 2013, 10:22:18 PM
Well, it is still oscillating, the voltage on the battery is now 334 mV, and the collector peaks are at 1260 mV, and the average collector voltage is about 340 mV.

So I am curious: this is the first time I've looked at the DSO's reported "average" voltages of the JT's spiky signal when the LEDs are not on but the thing is oscillating anyway. And I've noticed that the average collector voltage is nearly exactly the same as the supply battery voltage. Does this hold true for other JTs, I wonder? Do any of the JT researchers out there have any data on this question?

Meanwhile...

@ Shemp:  what happens in the sim if you "rotate" the transistor and hook it up incorrectly? That is, hook up the Collector of the transistor to the point in the circuit where the Emitter normally goes, and hook up the Emitter of the transistor to where the Base normally goes, and hook the Base of the transistor to where the Collector normally goes?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 02:16:41 AM
Want me to remove the 1.2nF cap?

I am finding this amazing because it is still going and the voltage hasn't seemed to slip any.  Might not be powering any LEDs but for something to be running this long and the voltage hasn't budged smells funny but in a good way.

btw, it seems my notifications are on but I am not getting any which is odd so that is why I did not reply as quickly as normal.

With or without the 1.2nf cap it doesn't oscillate.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 02:42:01 AM
Well, with my build using the MPSA18 transistor, I decided to put the board together first without the 1.2 nF cap, although I have the board drilled for it. I was going to wait until I had baseline data without it, before installing on the board. But it gave ambiguous results when I had the thing in its first build, the "deadbug" construction. When I get the BC337 transistors I'll be able to test the 1.2 nF cap properly.

So yes, for the rotated transistor test, I didn't use the 1.2 nF cap.

It is still oscillating. The battery voltage is down to 334 mV, the collector peaks are 1320 mV and the frequency is 529 kHz. Scope reports "average" collector voltage 330-340 mV.

Do you have a 2sc710 in the sim?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 02:51:45 AM
It does not but it does have the MPS line up (2sc/2sd are rare in it and I have had zero luck making my own even when I do exactly as it the tutorials say with datasheet in hand).

For it to have dropped only 3000 micro volts in this length of time it is hardly using any current to sustain its oscillation but I am surprised it is oscillating without a load too.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 02:54:41 AM
Sorry, I had the "rotation" test described wrong. But your schematic is wrong too! Your LEDs are now disconnected!
Please try the original circuit, but just hook the transistor as follows:

Base of transistor >  where the collector used to connect.
Emitter of transistor > leave in place
Collector of transistor > where the base used to connect.

So you just swap collector and base, don't change anything else from the original. Try with and without the 1.2 nF cap.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 02:57:21 AM
Naw, my screenshot chopped off the ground but it was there only hidden.

Let me run up the new stuff you want.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 03:00:32 AM
Same results with and without the cap.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 03:10:36 AM
Here's what I get:
First, "normal" orientation
Second, the "swapped" orientation: note the negative voltage excursions

It does this with the MPSA18, the 2sc710 and another thing called a "603" that I found many of in old TV chassis.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 03:15:56 AM
I get nothing like that.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 03:24:24 AM
Hmm... of course I just realized the signal of the swapped config isn't the collector signal anymore it is the base signal. So if I move the probe, too, over to the bottom of the base resistor/capacitor...that is, still on the collector of the transistor, I get the "normal" signal again.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 03:26:44 AM
I get nothing like that.

Well... hmmm.

Try lowering the input voltage back to 0.5 v
Try using the MPSA18 transistor, just to see if the sim will do what my hardware does

other than that I'm stumped.

My BC337 transistors will probably take a week to get here. They are supposedly coming from Colorado, we'll see, I guess.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 03:33:09 AM
Well... hmmm.

Try lowering the input voltage back to 0.5 v
Try using the MPSA18 transistor, just to see if the sim will do what my hardware does

other than that I'm stumped.

My BC337 transistors will probably take a week to get here. They are supposedly coming from Colorado, we'll see, I guess.
I will tell you that with the circuit you see and changing the transistor (I did this a few times already) to a MPSA18 the BC337 blows it away.  MUCH higher peaks in both voltage and current and the MPSA18 would not do these 4 transistors with the 1.2V whereas the BC337 has no trouble in the sim.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 03:34:13 AM
I just tried 2n2222 and it behaves the same, but with slightly less voltages.
Still using the same battery, and with the 2n2222 in there with collector and base swapped, the battery voltage is 382 mV.
With the 2n2222 the correct way round, the battery voltage is back to 358 mV.

And changing back to the MPSA18, battery voltage drops to 333 mV again. So the 2n2222 isn't letting as much current through it, and the battery isn't sagging as much when the 2n2222 is used. Collector peaks smaller too.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 03:35:01 AM
MPSA18
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 03:50:33 AM
MPSA18 without the cap.  Notice Channel B and its settings.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 03:51:38 AM
That's strange. I am using the same circuit, except without the 1.2 nF cap, and my MPSA18 keeps the 4 series LEDs lit down to a supply voltage of 0.650 volts, about, and at 1.4 volts (from DC regulated supply) the LEDs are brilliant.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 04:02:17 AM
You just made me check again. I wanted to make sure I had the MPSA18 in there! And it is.
I warmed the battery using the soldering iron to raise the voltage, and the LEDs come on visibly at a battery voltage of 0.610 volts.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 04:07:43 AM
You just made me check again. I wanted to make sure I had the MPSA18 in there! And it is.
I warmed the battery using the soldering iron to raise the voltage, and the LEDs come on visibly at a battery voltage of 0.610 volts.
Well, SPICE is not going to do it.  It could be anything causing it not to do a real world scenario but when you have over 30 different items you can adjust per simulation run there is just too much to handle.

This is making me despise simulations because there are some oddities that they can't simulate.  Sort of like a Tricorder from Star-Trek or that transistor identifier that doesn't know what something is until it sees it first, or is entered.  I am sure I could eventually get it to mimic real life but to what end and how many decades do I have to modify all of the data to get it to do it?  It is not something as simple as changing 1 parameter because when you change 1 another might have to be changed or it will error out.  Too many variables for me.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 04:12:05 AM
Here is one for you.  0.7V backwards MPSA18 and the probe is on the base and the ground (the ground is hidden below the LEDs but always remember it is there).
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 04:52:36 AM
Well, that's strange. I'd like to see that expanded, it looks like a single classical inductive ringdown envelope. Again, I'm not convinced you've captured a whole cycle yet there.

One issue might be the LEDs. I am using superbright blues, but I don't know the part number or manufacturer. My Fluke 83 DMM reports the forward voltage as 2.6 volts and the LED draws 220 microAmps at that voltage... and is already fairly bright. (Microammeter in series with the Fluke, with the Fluke in diode check mode.)

When supplied with a regulated DC supply (HP721A) the diode begins to glow visibly at 2.295 V and a current of 1 microamp! To put 20 milliAmp through it I need to go to 3.5 volts and the LED is blindingly brilliant.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 04:58:47 AM
Yes, it does look like that doesn't it?  This LED (I tried to make another and it never worked) is a BLUE LED
Vf = 3.45V @ 20mA but I am not certain about that because every LED says GENERIC / LED_RED so obviously National just did a C&P job.

I am about to put up the video of it on Youtube so I will post back in a bit.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 05:15:43 AM

You know I wonder if what is causing your continual oscillation could be because the circuit is actually inside the toroid and it is somehow having a case of feedback however minimal?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 07:24:35 AM
I don't know how to interpret what you are showing on the scope. You may have to go back to the single-shot search like I showed before, until you have a setting that displays a whole period in one screen, without clipping voltage.

It sounds like your LED model is quite close to what I'm actually getting with these LEDs. How does your sim tell you the LEDs are shining? I mean does it light up the symbol or what?

I don't think the circuit being inside the toroid makes a difference but it's easy enough to check... if this battery ever runs down, I'll separate out the board from the toroid and test again. Since I heated the battery up, it's back up to over 340 mV again... actually just now went down to 339 mV. Still oscillating at 492.3 kHz, with 1420  mV peaks.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 07:36:44 AM
Those little arrow symbols on the LED light up with the color of the LED being tested.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 07:43:09 AM
MPSA18 backwards.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 07:55:09 AM
OK.... that's the envelope of the single pulse. It doesn't repeat this, it just does it one time when you apply power?

I can see that there is more power dissipated in the MPSA18 than in the BC337, certainly. But why don't our waveforms look more similar? I'm pretty burned out tonight, I've been working all afternoon, but I'll do some more testing after I've had some shut-eye.

Sometimes JT circuits need to be kicked into oscillation. You could try putting momentary-contact switches between base and emitter, and between base and collector. Punching the switch for a few microseconds or a millisecond might work. At least the real hardware often works like this, even with big JTs using 2n3055s.

ETA: Can you move your trigger point over to the right a bit? You have it at the leftmost edge of the screen, and this prevents you from seeing what happens in the "pretrigger" time. In most of the shots I've shown, my trigger is set horizontally at screen center.  Try dragging the triangular icon at the top left of the screen, over to the third or fourth horizontal division.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 08:01:45 AM
OK.... that's the envelope of the single pulse. It doesn't repeat this, it just does it one time when you apply power?

I can see that there is more power dissipated in the MPSA18 than in the BC337, certainly. But why don't our waveforms look more similar? I'm pretty burned out tonight, I've been working all afternoon, but I'll do some more testing after I've had some shut-eye.

Sometimes JT circuits need to be kicked into oscillation. You could try putting momentary-contact switches between base and emitter, and between base and collector. Punching the switch for a few microseconds or a millisecond might work. At least the real hardware often works like this, even with big JTs using 2n3055s.

ETA: Can you move your trigger point over to the right a bit? You have it at the leftmost edge of the screen, and this prevents you from seeing what happens in the "pretrigger" time. In most of the shots I've shown, my trigger is set horizontally at screen center.  Try dragging the triangular icon at the top left of the screen, over to the third or fourth horizontal division.
Dragging them has no effect because, unlike a real scope, moving those llines neither increments nor decrements anything.  Sort of worthless in that respect and they don't hide anything either.

WOW, I can't explain it but the kicking worked.  It increased the current it was giving by a LOT too.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 08:11:39 AM
Wait, you are telling me that you can't offset the trigger horizontally?

Oh... you are using the analog scope sim. I forgot, sorry. Still, there might be a "delayed trigger" setting in there somewhere.

I wonder what the triangles at top left are for, then.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 08:13:06 AM
Dragging them has no effect because, unlike a real scope, moving those llines neither increments nor decrements anything.  Sort of worthless in that respect and they don't hide anything either.

WOW, I can't explain it but the kicking worked.  It increased the current it was giving by a LOT too.

Scopeshot?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 08:18:58 AM
About to put up another video so hang tight.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 08:25:54 AM
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 08:33:30 AM
It is weird and nothing like what the real device does. Your collector trace is flat at the battery voltage, it seems, so the circuit isn't actually oscillating, or you aren't catching it with the scope settings you are using. What you are showing now is very similar to what you had right at the start of the thread, with the positive/negative symmetrical sinusoid, isn't it?

How come you've disabled embedding?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 08:35:01 AM
Almost but not as symmetrical as that and the MPSA18 is backwards also channel A is on the base not the collector.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 08:47:00 AM
I don't know what you are seeing in that signal but it's not anything like a JT oscillation nor what I see with the reversed transistor. Look at my scopeshots, you'll see that I use the same timebase and vertical settings for both the correct orientation and the reversed one, far faster than your 5 ms per div.

Your scope in the video is set to 5 milliseconds per horizontal division, right? So the signal you are showing is at _exactly_ 500 Hz! It is less than 2 microvolts in p-p amplitude. This is not the circuit oscillating, it is a sim artefact, probably.

Look at the bottom left of the screen where it says "x pos. (Div) = 0" Try changing this to "3" and see if the trigger point moves over to the right.

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 08:50:08 AM
It does but not those cursors.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 09:00:42 AM
OK the cursor controls are probably the arrow buttons T1 and T2 at the left, just below the trace display window. The cursors should be vertical lines, and the position in time relative to the trigger point will appear in the window to the right of the cursor buttons once you move them off the zero line. The voltage levels where they intersect the traces will be listed there too.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 03, 2013, 09:04:17 AM
Correct and the point under the cursor that is moving shows you the time, and values of channel A and B that is under the cursor being moved but in a T2-T1 way.  So, move T1 and leave t2 at pos 0 and get negative numbers vice versa will get positive numbers.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 03, 2013, 09:57:35 AM
Got to crash, more later, goodnight.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 05, 2013, 10:25:34 AM
It is _still_ oscillating. It has stopped a couple of times but always restarts with a "tickle" across the emitter and base with a bit of wire. The frequency right now is 666 kHz, I kid you not, and the battery voltage is 330 mV.

Did the scope arrive yet? I forget, what kind of scope did you order?
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 05, 2013, 11:33:26 AM
It is _still_ oscillating. It has stopped a couple of times but always restarts with a "tickle" across the emitter and base with a bit of wire. The frequency right now is 666 kHz, I kid you not, and the battery voltage is 330 mV.

Did the scope arrive yet? I forget, what kind of scope did you order?
Only a BK 2120 with everything in their original packaging with the original manual shipped in its original box.

My fear is that if/when it finally shows up it will no longer be 100%.  I mean it was doing something for those 4 days and normally when that happens the USPS has messed up the package somehow.  From NJ to Memphis is a 3 day, max 4 day, USPS trip but just look at the tracking.

Lol, at the 666khz.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 05, 2013, 10:46:08 PM
Comparison of MPSA18 and BC337-25:

Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 06, 2013, 03:27:50 AM
Ran off of a battery?  The lower voltage tells me it is probably draining more current and giving, or trying to, more current to the LEDs.

Scope is in limbo land again as no new updates YET again.  I figure they drove this scope from NJ to CO and are driving it to here with no airplane usage at all.

Honestly I so hope it never arrives now so I can just get a refund but watch it arrive the last day.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 06, 2013, 04:44:09 AM
Ran off of a battery?  The lower voltage tells me it is probably draining more current and giving, or trying to, more current to the LEDs.

Scope is in limbo land again as no new updates YET again.  I figure they drove this scope from NJ to CO and are driving it to here with no airplane usage at all.

Honestly I so hope it never arrives now so I can just get a refund but watch it arrive the last day.
Yes, this is the _same_ battery that I have been running on from the start. I've heated it up several times, it just keeps on keeping on. Right now it's sitting at 329 mV and oscillating at 692 kHz, with the MPSA18. I want to see how low it will go with that, then I'll put the BC337 in there and repeat the test.

I'm amazed at the problem with your delivery. But last year I had a nightmare myself, two boxes of a three box FedEx shipment of my test gear got "lost" and wound up in Salt Lake City with no labels on them. I was able to describe the boxes to the CS agent (the fourth one I talked to) and she was able to get the people in SLC to go and search for them. They found them! The boxes were damaged but the stuff was so well packed that nothing was lost or damaged.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 06, 2013, 05:04:06 AM
Well, I am saving for a RIGOL 1102E anyway so if it doesn't get here I will simply demand a refund on my CC.  My issue is that PayPal sucks and sometimes will not send it over to the credit card and there is nothing you can do about it.  I called and called and had all sorts of people say it would get done and nothing ever did.  This has happened twice and the next time I will call my CC company and have it reversed off and PP hates it when you do that.  Tough noodles to them.

Anyway it has until Oct 9 so all I can do is watch and hope that if it does finally arrive everything is intact and not like the last package that had Kool-Aid all over the outside (I thought tranny fluid at first) then I opened it and all on the inside was liquid Kool-Aid.  Luckily they found my package and redirected it to me and the insides with my parts was completely sealed.

So, it will  be 3 days late and I will know what harm has come to it (hopefully) on Monday.  I was reading the 2120 manual on line so it tells me how to test it but this does tell me that this scope never entered a single plane to arrive here.  Consider about 3k miles of a journey all in the back of semi and tossed around between stations.  Just a little worried since this is a precision item AND it is not digital.  If it were all digital I wouldn't worry about it but with a CRT I do out of past experiences.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 06, 2013, 09:57:27 PM
It will probably survive.

The DALM thing is doing something very interesting now. I've just left it running, you know, using the same battery that has been drawn down and heated up several times already. Now it stops oscillating when the battery gets down to 300 mV or so, and when it stops the battery spontaneously slowly regenerates up to something over 350 mV and it starts oscillating again. I haven't been able to catch the exact voltage points where it does this but it has done it at least half a dozen times over the last few hours. It just turned off and the bat voltage is 374 mV and rising about 1 mv/sec.  So I'm watching....

Ah... caught it. At 481 mV it suddenly started oscillating again, at around 400 kHz and the voltage is dropping rapidly, already up to 606 kHz and 320 mV....

Weird, huh....  going through 666kHz at 328 mV.....
:-\
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 06, 2013, 10:39:56 PM
It will probably survive.

The DALM thing is doing something very interesting now. I've just left it running, you know, using the same battery that has been drawn down and heated up several times already. Now it stops oscillating when the battery gets down to 300 mV or so, and when it stops the battery spontaneously slowly regenerates up to something over 350 mV and it starts oscillating again. I haven't been able to catch the exact voltage points where it does this but it has done it at least half a dozen times over the last few hours. It just turned off and the bat voltage is 374 mV and rising about 1 mv/sec.  So I'm watching....

Ah... caught it. At 481 mV it suddenly started oscillating again, at around 400 kHz and the voltage is dropping rapidly, already up to 606 kHz and 320 mV....

Weird, huh....  going through 666kHz at 328 mV.....
:-\
666khz just shows this is one HELL of a circuit, lol.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: TinselKoala on October 07, 2013, 04:53:45 AM
Just so you know: I have the thing sitting on the bench and it is hooked up to the Simpson DMM for the voltage reading and also to a HP5381A frequency counter. So I just have to glance over there to see how it's doing. Right now it is not oscillating and the battery voltage is climbing  thru 474 mV, still at about 1 mV per second or maybe a bit slower.
Bingo! at 491 mV it spontaneously started oscillating again, batt voltage dropped to 335 mV and is slowly dropping from there. The frequency rise is quicker now, 720 kHz at 330 mV.
This is with the MPSA18, btw. I don't know if it does this with the BC337 yet.
Title: Re: Lidmotor's Penny circuit help needed.
Post by: Legalizeshemp420 on October 07, 2013, 11:20:25 PM
Scope seems fine and I am messing around with my simple JT and it does 3.2V at 43478hz.  Now I need a way to measure light intensity and it sure sucks not being able to measure, accurately and easily, the efficiency of this these.   I switched to my hand wound toroid and it was 635khz and the LED was barely on.  My sim said it would be 650khz so I was pretty close with the data I gave it for this coil.

I had to throw the HF/TV-H on this thing as it was wonky otherwise but I really need a bench top power supply because these batteries are not going to cut the mustard.  The problem is a bench top power supply with digital readouts is not cheap.