LEDs White LEDs
24VAC POWERED WHITE LEDs - Dec 20, 2009
Designed by David A. Johnson, P.E.
24vac is a popular voltage.
It is often used in low voltage lighting systems and industrial controls. It is
much less dangerous than 120vac/240vac line voltages. The circuit below is one
method to efficiently power a cluster of 7 white LEDs from 24vac. It uses a
classic bridge rectifier and filter capacitor to convert the AC to DC. A single
240 ohm 1/2 watt resistor limits the current to the cluster to about 20 milliamps.
Multiple clusters of 7 LEDs can be powered by repeating the basic circuit. The
filter capacitor should be increased based on the number of clustered powered.
The capacitor should be sized for 100uF for each cluster of 7 devices.