The "BATTERY SAVER FILTER" is a small, highly reliable switching power converter designed to provide filtered and regulated D.C. voltage to sensitive electronic equipment. The low ripple output voltage ensures noise-free operation of even the most sensitive devices. Short circuit protection is provided to protect from damaging overloads or shorting the output to ground. This device is especially useful when certain flashlight chargers are connected to the full wave rectified voltage supplied by a battery saver.