When voltage is applied to the coil then the relay switches and now T1 (plus ... In this second application we can use the DPDT switch to choose between 2 different load and have a visual indication ...

This Design Idea shows how to use a 63¢ (Q=1) microprocessor reset voltage detector IC in a relay coil drive circuit to greatly reduce the coil’s hold-in current. When asked to estimate the coil ...