Another simple one – the Conrad Buzz Box and Volume Expander – there is no volume expansion happening; this is just fuzz. 

This is an easy one to convert to NPN, and there’s quite a bit of discussion on the usual forums re transistors.  Good results have been seen with low-gain silicon in Q1, and germanium on Q2.   

There are also a few different schematics out there with varying pot values.  example:  100k for buzz; one even has 150k for both pots, which will be a little hard to find.

CONRAD BUZZ BOX – VERO LAYOUT