LM317T Voltage Regulator with Pass Transistor

Solid-state optoelectronic relay. Operational principleSolid-state optoelectronic relay is an electronic component used for switching electronic circuits. It provides electric insulation between check circuits, mostly between power circuits.All solid-state optoelectronic relays ensure a non-contact switching of load circuits due to the possibility of controlling its built-in semiconductor elements. This provides a number of advantages if compared with regular electromagnetic relays.So here is a design of solid-state relay. LED of input optical coupler acts as initial input element of an optical relay. Then there is also optical isolation, photovoltaic commutation, a switching circuit, and a protected output key.There is an LED in control circuit which transforms the flowing current into infrared radiation. Infrared light travels a certain distance in the casing, and falls onto the matrix of photogalvanic cells. Then it transforms light from the matrix into voltage which is used to control the element which locks the output key.If there is no current flow at the beginning of the circuit then there is no voltage and output key will open a commutation circuit.AC optorelay has a symistor at its output. It is peculiar in a way that the output key unlocks at a moment when switched circuit voltage goes through a zero. A bipolar or MOS transistor is used as output key in DC optorelays.A pair of source-connected MOS or IGBT transistors is used as a key in general-purpose relays ...



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