This circuit was found in documentation from the 90s. The operational amplifier admits an equivalent. The circuit has frequency ranges up to 5kHz determined by R1.
This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio...
This circuit was found in an American 1980s documentation. It analyzes the exhaust gas of a...
The components used in this 80's circuit are not common today. The circuit is very sensitive and must...