My first siren, tinkered with my old bike siren when I was a kid
like this one
(but an old one with real resistance easy to exploit, this one have certainly a black blob inside, but it is just to illustrate the type of toy)
4 select sound (laser, speed, long, 2 tons)
add :
switch on/off power,
voulume pot,
bass pot,
treble pot,
loop switch,
momentary push switch
pitch pot 1
pitch 2 / LFO mix pot ( ? i don’t see how it is possible but it works like that)
switch on/off LFO
Rate led LFO
Rate pot LFO
and add an old pedal delay (bypass switch, level, time, feedback)
555 circuit for LFO with vactrol, a passive tone circuit and all in a sort of cake metal box
Work on 9v power supply
cheap but fun