Using the 723 integrated circuit, this power supply has the voltage determined by R2 and R3, which can be changed. The circuit is from a Radio Electronics magazine from July 1971.
This circuit was found in a 1990 Electronics Handbook. The transistors can also be the BC548 and...
This circuit is from a 1987 American publication called Electronics Handbook. The circuit can be...
This 1995 documentation circuit detects when an extension on a phone line is active. Adjustment of the...