This circuit is from an article in Radio Electronics magazine from October 1958. The circuit is for testing electrolytics that operate at high voltages depending on the source.
This circuit is from a 1969 General Electric manual. The SCR may be the TIC106. Similar circuits...
This circuit was found in a January 1981 Radio Electronics magazine. The transistors are the well...
We found this circuit in a 1991 publication. It is intended for low-impedance microphones,...