This layout is based on a Crowther Hot Cake schematic by soulsonic and is one of several apparent versions of this circuit. Let me know if you successfully build this.
Update (24.03.2012): Built this one today and had the same issue a few of you have described. There’s a 0.5-ish second delay between toggling the effect on and the effect actually kicking in. I haven’t tried figuring out why this is (I’m thinking there’s a charge-up time , but a work-around would be to hard wire the effect on and instead wire it all true-bypass. I’m reluctant to call this one verified though.
Update (25.03.2012): Good news. After reading through the relevant thread over at FSB it turns out the schematic I’ve based this layout on was missing a cap between the “Presence” and “Volume” pots and this missing cap was causing the issue I was talking about yesterday. I’ve added the missing cap to the layout and verified that it’s now working as intended 🙂