Proof of concept to simulate zener diode switching of relays based on stepped control voltage. The first level is 8V, with the second at 16V. The left relay (5V coil) should come on above 6V of control and stay on. As the control voltage rises above 16, the right relay (12V coil) activates. Guarantees right relay will not trigger at lower control voltage level. Use the switch to change control from 8V to 16V
