Using red LEDs with ignition voltages of the order of 1.5 V we can make a multiple voltage reference. Current is low.
With the coded activation of the relays, it is possible to control which of the 16 outputs...
The integrated circuit used in this application is not very common. Transistors and resistors...
This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are...