This super regenerative detector circuit was found in an English documentation from 1963. The coil is frequency compliant. The transistors are germanium of the time.
ON Semiconductor Phototransistor Output Optocouplers Available from Mouser Electronics is the...
This precision rectifier circuit is suitable for applications in an AC / DC converter. We find it...
This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from...