Preamplifier stage (CB8934E)

This circuit is from a 90s Popular Electronics. It appears elsewhere on this site. Q1 can be any general purpose transistor.

Basic Non-Inverter Amplifier MC34071 (CB14491E)
This configuration is also valid for other operators and the formula for calculating the gain is...
Reinartz Oscillator (CB21135E)
This inductively coupled oscillator was found in an American documentation from the 90's. The...
Frequency Doubler (CB21065E)
This circuit was obtained from an Analog Devices manual from the 90's. The integrated circuit is...