Introduction
DC powered LED lighting circuits can vary from trivial
single LED/series resistor combos to simple analog current regulators to
more complicated switching power supply circuits such as this project.
There is a tradeoff between simplicity and circuit capabilities.
This more complex circuit adds features such
as regulated light level across a wide range of input voltages
and automatic circuit shutoff on low input voltage.
By using a high frequency switching regulator,
the power loss associated with the current dropping resistors found
in simpler circuits is reduced.
This offsets the power consumed by the circuit's active parts.
This circuit can power 10 white LEDs at 24mA of current with only 98mA
of input supply current when running on 12V.
LED intensity is fully regulated across the entire operating voltage range.
This circuit was inspired by F. Garcia's IR LED video illumination
circuit, published in the July 2001 edition of Nuts and Volts magazine.
I modified the LED count and feedback circuit, and added the important
low voltage shutdown feature.
