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Old 6th May 2020, 4:28 pm   #8
Chris55000
Nonode
 
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,873
Default Re: Reverse engineering Lumenition optical switch

His!

From my industrial electronics experience, IR emitting LED devices almost always have a "water clear" package encapsulation, whereas IR photodiodes have a purplish (or dark blue/grey or even black) transparent package!

It's easy to test which is which if you have a current limited supply, or a 9V battery and a 1k resistor available – simply connect your water–clear device to a 9V battery via a 1k resistor in the forward direction and point your 'phone camera at it!

For circuit–drawing purposes, the purple–tinted device can simply be represented as a diode with two inward–arrows at 45° pointing towards it!

Photo–diodes are normally operated in the reverse–bias direction as a rule!

Chris Williams
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