Using components from the era, this 90's EDN circuit is used in analog to digital conversion circuits. Components are not currently common.
A load of up to 3 amps can be controlled by this circuit from a low current switch (reed-switch or other)...
This control circuit for incandescent lamps was found in a publication from the 90s. The circuit uses...
We found this circuit in an old French documentation from the 70s, but it can be assembled using...