We found this circuit in the Linear Applications Handbook of the 1994 National Semiconductor. The transistor must be a high voltage type and the LM3900 power supply must be symmetrical.
This transformerless power supply uses an SCR as a regulator. It was found in a Popular...
This circuit is from the American magazine that no longer exists Science & Electronics,...
Suggested by an old Popular Electronics, this circuit is based on an uncommon integrated today,...