This is an interesting configuration of the LM317 voltage regulator found in an EDN from the 90s. The circuit uses an optical coupler and is intended to supply constant current to a sensor resistor.
This circuit was obtained in an old American publication from 1978. It can be assembled with a...
Decade counters, such as the 4017, can be cascaded as sourcing signals with the frequency divided...
This circuit uses a dual-gate MOSFET, a rare component today. We found it in American...