Abstract: A regulated power supply includes a transformer having a primary winding coupled to an AC power line, and a secondary winding coupled to a rectifier. A storage capacitor is coupled through a switching transistor to the rectifier, where the storage capacitor provides a DC output power terminal. A control circuit having a comparator amplifier is coupled to the secondary winding and to the switching transistor, and compares the voltage from the secondary winding to a reference voltage value. The switching transistor is turned on from 0 to positive voltage values, as output by the rectifier, to regulate the voltage applied to the capacitor. The switching transistor switches off when the input voltage value equals or exceeds the reference value. Several passive circuit elements (e.g., diodes, resistor-capacitor networks, etc.) slow the turn on and turn off time of the switching transistor to help eliminate switching noises and other EMI.