This amplifier with two FETs in direct coupling (cascode) was found in a 90s Popular Electronics. The MOSFET can be of almost any type like the MPF102.
We found this circuit on Radio Electronics from July 1990. It triggers a relay with a touch of the...
These three circuits have different treble responses. We found them in the February 1970 issue of...
This photoelectric cell light relay was found in Radio Electronics magazine from April 1958. The...