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.
This circuit changes the wave shape of a square signal according the values of C1 and R1. Other...
This circuit provides a reference voltage for calibration. He uses a diode in a small thermal...
Found in an Electronic Design from the 80's, this circuit monitors the charge of a 12 V battery....