This circuit was found in a 1989 publication. The operational amplifier supports equivalents. The LED range can be expanded.
This circuit with 117 V output was found in a 1969 Electronic Design. Drive transistors admit...
This project came out in an article of mine (Newton C. Braga) in the Popular Electronics magazine of...
Found in an Electronic Design from the 80s, this single cell charger uses an integrated circuit...