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LED type component identification help

J

Joel Dorfan

Jan 1, 1970
0
I took appart a daylight switch (comes on at sunset and off at sunrise) to
see why it wasn't working.
Expecting the usual light dependent resistor inside instead was what looks
like a normal 5mm clear LED as the light detector.
Close inspection shows that it does not have the usual phosphor type die but
instead a little dark coloured square of material with the little wires
attached.
Resistance does vary with light but increases as it gets darker instead the
other way around as usual.
Using the diode checker it shows 1.7 across it when the corect polarity is
observed and 0 when the polarity is reversed. (the component was in circuit
at the time)

What is this component? Could it be an LDR in an LED type package?

TIA

Joel
 
G

Gary Tait

Jan 1, 1970
0
I took appart a daylight switch (comes on at sunset and off at sunrise) to
see why it wasn't working.
Expecting the usual light dependent resistor inside instead was what looks
like a normal 5mm clear LED as the light detector.
Close inspection shows that it does not have the usual phosphor type die but
instead a little dark coloured square of material with the little wires
attached.
Resistance does vary with light but increases as it gets darker instead the
other way around as usual.
Using the diode checker it shows 1.7 across it when the corect polarity is
observed and 0 when the polarity is reversed. (the component was in circuit
at the time)

What is this component? Could it be an LDR in an LED type package?

TIA

Joel

Probably a photodiode or photo transistor.
 
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