You can find all info and schematic on their website here.
The original circuit uses a 1M Lin Pot with internal switch for the "Self Oscillation".
I've used a regular pot and an extra SPST switch but you can just use the original if you prefer.
Here's a collection of vero (stripboard) and tagboard guitar and bass effect layouts that we have put together covering many classic and popular effects in growing numbers. Many of these have been posted on freestompboxes.org, so check that site out for great discussions on building your own effect pedals. Enjoy the builds and please also visit us on Facebook and Twitter