This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio Electronics magazine. The circuit is based on an LM324 and a sensor from that time.
This circuit was suggested by Motorola in a 1980s publication. It is based on a PUT that is not a...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...
This is an old circuit, but totally viable and with excellent sound quality. BD transistors must...