We found this circuit in an American publication from the 90s. It generates pulses that can be modulated in amplitude. The supply can be done by voltages from 5 to 12 V and the frequency depends on C1 and C2.
Placed in the vicinity of a telegraphic transmitter (CW), this circuit produces an audible signal on...
Damped oscillators can be used to produce sound from percussion instruments such as the triangle, bell,...
We found this circuit in a 1983 English magazine, but it can be easily assembled with the BC548...