This old amplifying stage was found in radios and small amplifiers of the time. The circuit is from Mullard's transistor reference manual.
This interference rejection circuit for telegraphy was found in a 1980s documentation for radio...
This circuit was found in a 90s Popular Electronics. Both the coupler and the MOSFET can be of any...
This is a traditional oscillator configuration with an operational amplifier using a symmetrical power...