Mr. Multi Build Report

[RickL]

I finished this up a couple of days ago and after a bit of debugging it's mostly working. Info in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=35644.msg251017#msg251017

First, there are a couple of small errors on the layout. The 4k7 resistor from 9v to the drain of the FET on the top of the layout is missing. I used the empty pad attached to the drain and the pad for 9v and moved the 9v connection a little higher up on the trace.

The 330k and 220k resistors mounted on the selector switch are reversed (or the schematic is wrong).

Also, I had to use a 4.7 volt zener to get anywhere close to 3.5 volts at the spot indicated on the schematic. I started with a 3.6 volt zener but voltage measured about 2.5 volts in the circuit and the effect sounded weak.

I used unmatched 2SK30s from Small Bear and TL074 and TL072 for the opamps. The trimmer had to be adjusted all the way to one side for the deepest effect. Note also that two poles of the 6p2t switch aren't used so you can use a common 4p3t rotary switch with the tab moved to give only two positions.

Wah and Double wah sound great in both manual and automatic positions of the switch but phase is pretty weak, almost unnoticable in the manual position. I'm not sure if the problem is the unmatched FETs, the trimmer or something else. I'll try matching the FETs better to see if it helps but I'm still uncomfortable about the zener and the trim position.

Any comments welcome.

[Eb7+9]

you're a brave one Rick ...

I'll check that stuff out later when I'm not over my head in flux - thanx for the feedback

~jc

[Basile]

Well I have noticed a error in the schematic. This will have no effect if RickL have buid his clone with the PCB.

Where 3 diodes are in series, betwenn the connections (10) and (11). The wire between the 470k resistor and the slider of the trimpot, does notlink with the connection (10). But if you check the layout, you'll see that there's one diode between the connection (10) and the wire of the 470k resistor and the slider of the trimpot.

well I hiope this might help!

Basile