This device basically works like a switch, connecting two isolated circuits on your PCB. An Optocoupler effectively isolates an output and input circuit. It can also be connected to ground with an external resistor for a higher degree of control over switching sensitivity. The photosensitive device is typically left unconnected by default to provide the highest sensitivity to infrared light.

When the light hits the photosensitive device, it switches on and starts to conduct a current as any ordinary transistor might. ( Image source) How It WorksĪ current is first applied to the Optocoupler, which makes the infrared LED emit a light that’s proportional to the current. At a glance, it’s easy to mix up an Optocoupler with an integrated circuit (IC). Both of these parts are contained within a traditional black box with a pair of pins for connectivity. Let there be light! This device allows you to transmit an electrical signal between two isolated circuits with two parts: an LED that emits infrared light and a photosensitive device which detects light from the LED. Need to protect sensitive, low-voltage components and isolate circuits on your PCB? An Optocoupler can do the job.

Learn how an optocoupler works to safely separate high-voltage components and low-voltage devices while removing electrical noise.

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