Found in Popular Elecronics, this configuration also appears in this section, but obtained from other sources. The 14.4 V supply allows the circuit to be used in the car.
The displayed relay operates with an audio signal applied to the input. The transistors can be...
Found in a 1980s Electronics Now, this circuit uses common components. Transistors are commonly...
To control relays or DC motors safely with double isolation via the parallel port, we suggest the...