An electrical power-switching circuit controls power to an electronic device. In some embodiments, the circuit consists of only transistors, resistors, and capacitors, making it small, low cost, and functional over a wide range of supply voltages. The circuit may be switched on and off by a momentary-contact switch. The circuit can be constructed so that, except for transistor leakage current, no power is consumed in the off state, and the controlled device can shut off its own power.