This circuit was found in a 90s Popular Electronics. It generates tones given by the oscillators and can be changed. The circuit already includes an amplification stage.
Found in American documentation from the 1970s, this circuit employs an integrated circuit from...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This assembly circuit using a small motor as a generator was found in Radio Electroics magazine from...