Single polarity circuit

摘要

A circuit with low impedance for maintaining a single polarity at an output is disclosed. Switching is provided by light controlled switching devices which in one embodiment are field effect transistors (14, 15, 16, 17) which are optically triggered by one or more photo-responsive devices (26', 27', 28', 29') coupled to their gate electrodes. The ON-OFF state of each switch is determined by the presence or absence of light from an adjacent line-powered LED (26, 27, 28, 29). A diode (32, 33, 34, 35) may be included in parallel with each switching device to provide surge protection.