PWM Voltage Dropper

This circuit was developed to allow a car trailer, designed for 12 V operation, to be used as a trailer for a van with a 24 V supply. A number of copies of the circuit we made, for the left and right indicators, brake lights, number plate light and reversing lights, and these have been in trouble-free operation for several years. The advantage of this compact circuit is that it dissipates very little power because it uses pulse width modulation. In addition, its quiescent current consumption is practically zero.