As you can see in the schematic the 12V battery (or use other voltages) is connected with the plus at terminal T1 and minus at terminal T2. The contact 1 and 4 are connected together as 2 and 3 are ...

I designed this relay circuit to function as a DPDT toggle which is controlled by a momentary switch. I strive to keep my circuits simple with little or no integration (555’s, transistors, etc). The ...