Few realize how close an optical coupler resembles a relay. It is so close, in fact, that one can be wired as a Run-Stop latch circuit. One advantage over the relay is that it may be turned off via a ...

This circuit allows an SPST momentary pushbutton to act as a push-on push-off switch, using a DPDT latching (bi-stable) relay. It was originally intended to allow a single pushbutton switch on the ...