Found in a 1990s American technical brochure, this circuit is intended for alarms that use as photodiode sensors. The circuit has a frequency response of up to 20 kHz. The gain is 40 dB.
This series sensor circuit is from 1995 Popular Electronics. The circuit can use any SCR and the...
This reinforcing stages from a 1960s documentation. No information is given about the transformer...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...