shocktave

[GFR]

I've tried simulating the shocktave in Circuitmaker and it didn't "work" (no octave down). After some tweaking, I've managed to make the simulation behave as expected (that is, with a octave down "square wave" at the output). This is only simulating, but maybe this can help people that have built it but doesn't get the same tone as the samples.

What made the octave down appear was tweaking the Zener voltage of Q3 BC junction. If this was too high the octave down didn't happen. Around 6V-7.5V the octave down appeared. And, by lowering it to ~5V I got two octaves down. And so on When it's over 7.5V there's no clear octave, just weird harmonics. At >9V there's almost no effect.

So you could select transistors by their BC Zener voltage. Warning: testing the zener voltage of a transistor can make it noisy (for "normal" applications; for Q3 in the shocktave it shouldn't matter).

Or one could try selecting a Q3 with a very high BC zener voltage and put a zener in parallel with the BC junction. You could switch different zeners for different effects Or you could use a VBE multiplier circuit instead of a normal zener and have this adjustable by a pot  :shock:

Now I got to build one!

EDIT

I was simulating without the volume pot, I just put a 1MEG resistor in place of the blend pot. After puting a 100k resistor to ground at the output it simulated OK without the zeners  :oops: - just like Paul Marossy's simulation in the other thread.

http://diystompboxes.com/sboxforum/viewtopic.php?t=29940&postdays=0&postorder=asc&highlight=shocktave+circuitmaker&start=15

I also tried exchanging Joe's single transistor charge pump for the single transistor charge pump I found somewhere else, it simulates OK too (plus for this one I think I understood how it works ).

http://diystompboxes.com/sboxforum/viewtopic.php?t=29940&postdays=0&postorder=asc&highlight=shocktave+circuitmaker&start=15

[Sidd]

"Around 6V-7.5V the octave down appeared. And, by lowering it to ~5V I got two octaves down."
I realize it's simulated without the volume pot (100k resistor to ground at the output). But does this suggest this circuit might also be able to do two octaves down? I don't have enough knowledge about electronics to tell, but perhaps by selecting a Q3 transistor by the B-C zener voltage it could. Otherwise using a zener diode with the right breakdown voltage in parallel with the BC junction might do the trick?