That's just a volume knob in a box, no vero necessary.
Here's the schematic. Wire a 1Meg log pot like a volume knob (lug 3 from input, lug 2 to output, lug 1 to ground), and use a DPDT to switch it in and out. If you want an led you'll need a battery or adapter and a 3PDT, but otherwise there's no power required.
The original has a 220p cap between lug 3 and lug 1, but some people complain it sounds muddy, so you may want to experiment with smaller values (or leave it out completely). If you want it to get brighter when you switch it on, put the cap between lugs 3 and 2. Again, play with the value until you find what you like.
Locked
