Anyone know what sort of sensor these use? 2 of mine have died and it's the cell wot dun it. One seems to have gone open circuit and the other short circuit (one won't switch on, the other won't switch off, I've removed the cells and the lamps work ok, except they are on all the time).
Bob
Can you describe them or upload a photo somewhere ? I'm guessing they're transparent LED-like things with no writing on 'em ?
Was it just a 2 wire cell ? if so a Royce Thompson P42 cell may work. Jon.
I suspect that's overkill :-)
just a photodiode should do it - just wondering why it failed - sounds like the lamp is driven by a seperate transistor ...
they look like the ones on top of some streetlights .....
I remember scraping the paint off OC71s in the old days ...
I see Maplins only do a couple of non-infrared ones - 79p with a 100mW max dissipation - which is quite a lot in that context - what power lamp do the things have ?
Jeremy
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I've opened one of the lamps up and inside there is a small circuit board containing a few resistors and 2 transistors. There is a single large-ish LED which provides the light (amber) and where the photocell is connected it's marked 'CDS'. It's powered by 2 AA size ni-cads which I removed and charged seperately, they were OK, just flat. The photocell itself has no markings, it's in a translucent package which looks like it was moulded to fit the space in which it fits, looks a bit like a flat-sided bowler hat (but somewhat smaller!). Had a look in the Maplin cat but nothing that looks like it in there, I wonder if one of the cells they have might work anyway? I could upload a pic but have no idea where to, I don't have a website.
Thanks for your help
Bob
That must stand for CaDmium Sulphide - which suggests it's a Light Dependent Resistor (LDR) probably used for low supply voltage / efficiency reasons.
Jeremy
Thanks again
Bob
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