Single Coil Two Transistor Boost Circuits

[Farmhand]

Here's a higher resolution shot of the wave form, just need to work out how to make it display more info.

[Farmhand]

Interesting behavior from a circuit on a hand drawn PCB made to take the little logic gates soldered to the adapter's.
The circuit worked as above post shows in normal mode, then when the input capacitor voltage dropped down to about 0.75 volts the
circuit flickered the LED's for a few seconds then they light up even brighter because the circuit was operating at well over 300 kHz in
a odd feedback kind of mode (no ring down). I made a mistake on the hand traced board that I had to fix using a jumper and
stretching my timing caps out. I made the traces so I can solder the SMD mosfet on the back as well I can solder SMD Shottky's on
the back as well if I want later, 1N5819's for now.

Now the real interesting part, it ran for about an hour from a 50 Farad capacitor charged to 1.16 volts even using the MPSA06 transistor.
I ran it down to 0.68 volts and it was still lighting the LED's pretty well but sucking the voltage down on the cap in the higher frequency mode.
Not sure if it will do that with a mosfet.
..
scope shot shows the wave form when the circuit is in the low voltage high frequency mode. I'm only lighting 2 x 5 mm LED's now instead of three.
.

[TinselKoala]

Here's a higher resolution shot of the wave form, just need to work out how to make it display more info.

You may find this video of use:

http://www.youtube.com/watch?v=9FDmkbCbKP0

Also, you could position your X1-X2 and Y1-Y2 cursors a bit better; at the moment they don't seem to be related to the waveform, you just have them at arbitrary locations on the screen.

I don't know what the Rigol can display in terms of "measurements" or "parameters" that it determines from the waveform itself, especially with a burst oscillator like some of our JTs. You will probably have to do an exploration, like I showed in the video, and also use the cursors in various positions once you have a stable display of an interesting feature of the waveform or pulse train.

Nice work all around though, I'm tempted to build a "twofer" myself.

[Farmhand]

Yeah I just grabbed that picture while I had it there, the communication between the scope and the computer is flakey, so I was
sidetracked  trying to work out why, I was lucky to get that, I think it could be the cable.

I had to order a laser printer online, maybe a week I'll have more stuff to play with, time to install a new motherboard in my desktop
computer. Laptop is a bore to type on. Thanks for the tips. I've cleaned the cable connections so I'll try again. Might work better with Linux or windows 7, this laptop is XP. USB sucks with XP.

Looks like I'll get at least the same 1 hour's run time from the second 50 Farad capacitor. The LED's have about 5.4 volts across them mostly.

Works out to about 22 Joules for an hours run.

[TinselKoala]

Yah, the LEDs will always act as a kind of voltage regulator, you will rarely get more than the sum of the spec fwd voltages when you measure across the LED stack. But I've got oscillators like this that will work without the LED load being in place (so it's kind of like driving a really really high impedance load). In this case the voltage can go quite a bit higher. You might try putting more LEDs in series as the load and see how high the oscillator will push the voltage. I've also found that the different colors of LEDs behave quite differently. Some have a very sharp "turn on" and others, like these red superbrights I have, seem to "leak" substantial current well before they start glowing visibly, and do glow at lower voltages than blues or whites.
Try four blues in series and see if the voltage goes high enough to light them.