Kechiwah build report

[RickL]

I love Tim Escobedo's designs. I built this last night on a bit of perfboard and it worked perfectly from the start. I used a 1 M pot and a 330 k resistor in place of the 1 M input resistor and a 100 k volume pot.

It doesn't quack quite like a Clyde but it's pretty good. Well worth building. There's a bit of dirt with the input pot cranked but it cleans up nicely with the pot turned down with still enough gain to get unity volume with the volume pot all the way up.

Since all my 1 M pots have a built-in switch I used it to disconnect the 1 nF cap going to the source of the J201. This turns it into a nice little booster, a little bright but still good. Note that this mod disables the frequency pot. I also used a SPST to switch a pair of back-to -back diodes across the collector and base of Q1. This makes it a distortion with the frequency pot still active. Si diodes worked best, Ge's were useless and 1 Si and 1 LED also worked but not as well as 2 Si's.

Great work as usual Tim.

[Tim Escobedo]

Thanks. It's a bit unusual, but works ok.

I just posted a new CMOS based wah circuit, a Twin-T variant, that's a decent sounder. The bass end isn't as bassy as others, but sweeps up to a nice treble peak. And the CMOS sounds good to my ear even when it breaks up. As usual, the resistance to ground can be just about anything. Another interesting thing is that only one inverter is used. There are five more available, and using them shouldn't have any power consumption penalty. Though if any are used as oscillators or high gain sections, the power will need  substantially more bypassing.