This audio circuit was published in a Rado Electronics issue from October 1963. The transistors are from the time and the output is low impedance. Power is supplied with a voltage of 12 V.
We found this circuit in the August 1970 issue of Radio Elecronics magazine. It uses the CA3018...
This circuit was found in a 1997 documentation. The signals are adjusted in a double 555 (556) and the...
This circuit was suggested by Sprague Electric in an 80's documentation. The circuit uses a...