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Author Topic: Lidmotor's Penny circuit help needed.  (Read 52569 times)

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #45 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.

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #46 on: September 29, 2013, 06:24:35 AM »
Here is something I found and you tell me - www.youtube.com/watch?v=EARtlFx0gpk

Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #47 on: September 29, 2013, 04:49:22 PM »
2us a div and showing the .1 ohm resistor.

Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #48 on: September 29, 2013, 04:49:48 PM »
500ns/div

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #49 on: September 29, 2013, 04:54:27 PM »
2us/div showing the circuit as well.

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #50 on: September 29, 2013, 04:54:50 PM »
500ns/div to zoom in on it.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #51 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.

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #52 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.

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #53 on: September 29, 2013, 11:34:25 PM »
I can't seem to get rid of that huge negative current spike.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #54 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.


Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #55 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:

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #56 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.


Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #57 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.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #58 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:
http://www.youtube.com/watch?v=Qx3B89379eQ
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.



Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #59 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.