Switching applications involving controlling devices or appliances using digital-I/O lines through a relay often need to indicate the change of state of the I/O line and, hence, the connected device.

Over the years, control relays of various types have been used by the hundreds — even thousands — to control nearly every function in commercial and industrial processes. Today, many of those ...

Many varieties of ON/OFF control circuits use some form of flip-flop that responds to a pushbutton switch or other control input. These all have volatile memory and default to an OFF condition if ...

When it comes to electronics, it seems like a relay is such a simple device – yet, it is able to interface some pretty elaborate high-end systems with a fire alarm system. Working with relays is an ...