Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
I was looking though a digi-key catolog and I came across many pages for a part called an Optoisolator. I was wondering what it does and what simple applications it is used in.
It's an optoelectronics device that focuses a light emitter upon a light-sensitive detector, the two devices separated by a transparent, non-conductive barrier. They're used primarily to isolate two circuits that are at drastically different voltage levels or to isolate two circuits that must have independent grounds. Typically, it's an LED as the emitter and a phototransistor as the detector. Others have PIN diodes or light dependent resistors (LDRs) as the detector. Before the advent of the LED, folks used to "roll their own", using an incandescent lamp as the emitter and an LDR as the detector. There were some early electronic organ manufacturers that used them in the "swell" (volume) pedal so that the pedal controlled the incandescent lamp intensity and the LDR detector was part of the volume control voltage divider. They did that to eliminate the problems caused by noisy pots as the slow response of the lamp filtered all the scratchiness out.
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