This circuit is from 1967 General Electric documentation. It uses SUS which are not very common components today. The maximum frequency should not exceed a few kilohertz.
This interesting project was found in a 1995 documentation. It controls the temperature of the...
With NAB equalization we found this circuit in an English documentation from 1967. The transistors used...
This stabilized source can supply currents up to 700 mA and the output voltage is close to 15 V. a...