This circuit was found in a 1969 Mullard documentation. Used transistors can be replaced with modern equivalents. Output transistors may be BD135 and 136 with heatsinks.
This circuit was found in Motorola's 1968 documentation. The SCRs are then replaceable with...
This temperature compensated circuit was found in a Popular Electronics of the 1990s. The circuit...
Suggested by a 90s EDN, this circuit supports almost any LED as a source and a phototransistor as a...