This circuit was found in a Mallory documentation from 1968. The integrated circuit is of the time, unusual in our day. Input sensitivity is 20 mV for 2 W output.
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...
This circuit produces a strong tone of audio or ultrasound, depending on the values of components C1 and...
This alarm from an old 1978 publication uses PNP transistors and driver and output transformers that are...