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 circuit for signals up to 30 MHz can improve your reception in the medium and short-wave...
This circuit can be used as a shield for transmitting the temperature of a sensor. The circuit is from...
This astable multivibrator follows the traditional configuration for use as a signal injector, found in...