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 ...

Computers built using discrete logic chips? Seen it. Computers from individual transistors? Impressive, but it’s been done. A computer built out of electromechanical relays? Bring on the ozone! The ...