And it depends on the turn-on threshold of the tremolo transistor (TR-1) and reverb transistor (Q103). You could test it by putting a milliamp meter to ground from each source to see what the normal turn-on current is. Then add progressively larger resistors in series to find the turn-on threshold current (when the effect no longer turns on.) If it's more than 2-3 mA or so, you could power a fuzz.