This 1967 Raytheon circuit uses a Raystor, an optical coupler with a lamp and an LDR. The circuit can be adapted to use another type of coupler.
Currents of a few tens of milliamps can be obtained with this simple source that makes use of an...
This circuit was obtained in a 1990 English magazine. The circuit can be assembled with equivalent power...
This circuit is recommended by Texas Instruments in the datasheet of the TL317, equivalent to...