1) I also thought so, but was mistaken.
Although they are more sensitive to yellow-green (about the same as us), red leds work much better (just test it yourself)
The explanation is counter-intuitive but logical: our sight is much less sensitive to red than to yellow-green, so red leds are *heavily* doped to be seen at all, and high efficiency ones even much more.
They swamp the LDR with photons.
Hands-on experiment supports theory.
2) I live in Buenos Aires, Argentina, and pay 0.25U$S each, which qualifies as pennies to me , compared to any Vactrol or whatever.
I buy 200 unit bags straight from the importer/wholesaler.
I attach a sheet from his catalog.
He is no Mouser, he sells only to shops or factories.
In theory they shouldn't sell *me*, but after 41 years in one trade, one gets to know everybody, sort of.
Although they are more sensitive to yellow-green (about the same as us), red leds work much better (just test it yourself)
The explanation is counter-intuitive but logical: our sight is much less sensitive to red than to yellow-green, so red leds are *heavily* doped to be seen at all, and high efficiency ones even much more.
They swamp the LDR with photons.
Hands-on experiment supports theory.
2) I live in Buenos Aires, Argentina, and pay 0.25U$S each, which qualifies as pennies to me , compared to any Vactrol or whatever.
I buy 200 unit bags straight from the importer/wholesaler.
I attach a sheet from his catalog.
He is no Mouser, he sells only to shops or factories.
In theory they shouldn't sell *me*, but after 41 years in one trade, one gets to know everybody, sort of.
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