Lidmotor's Penny circuit help needed.

[TinselKoala]

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.

[Dark Alchemist]

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

[Dark Alchemist]

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.

[TinselKoala]

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.

[TinselKoala]

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.
http://www.youtube.com/watch?v=zM1qdATaiks