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Author Topic: Lidmotor's Penny circuit help needed.  (Read 52562 times)

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #60 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.


Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #61 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.

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #62 on: September 30, 2013, 02:56:59 PM »
BOOM, lookee there.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #63 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




TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #64 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

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #65 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.


TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #67 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

Dark Alchemist

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Re: Lidmotor's Penny circuit help needed.
« Reply #68 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.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #69 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.



TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #70 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.
« Last Edit: October 02, 2013, 01:46:37 AM by TinselKoala »

Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #71 on: October 01, 2013, 06:48:58 PM »
 ;D  Now if we could only tap into those oscillations to do something with.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #72 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.
« Last Edit: October 02, 2013, 01:47:36 AM by TinselKoala »

Legalizeshemp420

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Re: Lidmotor's Penny circuit help needed.
« Reply #73 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.

TinselKoala

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Re: Lidmotor's Penny circuit help needed.
« Reply #74 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?