Found in a 1992 book, this circuit is intended for operation with audio signals. Equivalent operational amplifiers can be used. The optical coupler is an unusual type today.
The current can be kept constant in the load circuit using the integrated regulator LM350. The...
Found in older documentation this setting applies to modern components, noting that the power...
This circuit is suggested by American documentation from 1970. It makes use of transistors of the time...