This circuit uses a lamp driven by the Hertz loop and measures its brightness with ordinary photovoltaic cells. The circuit is from a Radio Electronics from February 1964.
The integrated circuit used in this stereo preamp is uncommon today, but the circuit can be...
This circuit was found in a 1967 General Electric manual. It is intended for the control of high...
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...