These 6 to 12 V source with current up to 100 mA was found in Radio Electronics magazine from June 19666. The source has a current indicator and uses transistors of the time.
January 2017 - Through Mouser Electronics Texas Instruments is launching its new zero-drift...
This circuit can be used to test continuity or even semiconductors. We found the configuration in a 1987...
I found this circuit in an Electronics Handbook from 1989. The circuit can be assembled with a...