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Changing the sensitivity of a photo cell

earachefl

Apr 6, 2014
2
Joined
Apr 6, 2014
Messages
2
I've inherited a 12V outdoor lighting system with a rather old controller, a Twilight CB-150MD model. The dusk-to-dawn light sensor never seemed to work so I managed to track down the manufacturer in Taiwan and had them send me a replacement. After installing it, by trial and error I found that it only by shining a flashlight directly on to the sensor could I get the system to think that it was daylight. Obviously the sensitivity needs to be adjusted but my electronic knowledge is limited. I'm fairly handy with a soldering iron so if anybody thinks they can give me an idea of what to try, I'm game. I've tried asking the manufacturer for help but have gotten no response.

Attached are two pictures of the circuit board. The light sensor is attached by the two wires, black/white striped at the top (marked CDS) and white. By looking at the bottom of the board, I can see that R1 is directly wired to the white wire. Would it be safe to assume that R1 controls the sensitivity? To raise the sensitivity, would you try raising or lowering the value of R1, and by how much? I don't have one of those gadgets to try plugging in different resistance values.
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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I'd suggest you email them, tell them your problem, and see if they have a solution.
 

davenn

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Sep 5, 2009
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you haven't actually shown us the sensor

maybe you could replace it with an style that performs better

Dave
 

electro_pa

Aug 14, 2011
16
Joined
Aug 14, 2011
Messages
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I suggest it would be easier just to chuck it an buy another which works! At least if that new sensor is unsatisfactory, the retailer is required to exchange it.
12 volt systems are available. Are you stuck with 12 volt supply? 240 volt units are easy to convert, since almost everything you need is already on the board. most work the innards at 9 volts. 240 volt relay can be swapped over.
Regards, Clive Judd.
 
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