Ive done quite a few designs using these little pentodes, and heres a trem The tremolo speed goes from machine gun fast to is it still on slow. Even slower speeds can be obtained by changing the speed pot for 47K or 100k, but for a useable range 22K or 27K is just fine. I power all my effects off a 12 volt supply, which with this effect means a decent amount of clean boost is available in addition to the tremolo. Powering it off 9 volts will give less boost.