I found tis circuit in na old documentation from 1958. The circuit uses germanium transistor availble that time and hard to obtain today. The circuit is indicated for phono applications using variable reluctance transducer.
This detector is from the 1990 Motorola Dataar Databook, but can be adapted to work with more...
This circuit is from an Electronics Now from August 1995. The triac is according to the load that...
This circuit is from a Hands-On Electronics from the 90s. The integrated amplifiers used are well...