Motion sensor for outdoor security lights

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
Anybody know where to get this kind of thing for cheap? So far, all the replacement modules I can find cost as much as an entire new fixture (light sockets and wall plate included). I guess those cheap metal parts are nearly free and you're paying for the electronics.

I've got an outdoor security light that is showing sporadic behavior. Replacing the cadmium sulfide light sensor cell helped a little but was not a full repair. As I was playing around I discovered that when the light was stuck in the wrong position for no apparent reason, tapping gently on the relay on the PCB would cause it to correct itself. So I pulled the relay and tested it on the bench. It's rated for a 24V coil drive and I tested it at 12V. It clicked very reliably on 12V. So my theory is that some other component on the board is preventing enough power from reaching the relay coil. These things are pretty cheap, so that's pretty much a death sentence for the old PCB. Easier to just buy one than to try a repair.

But I'm perplexed that I can't find one for a few bucks.

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ericgibbs

Joined Jan 29, 2010
10,441
hi W,
If the relay contacts are driving a high wattage lamp, say 400W/500W, I have found that the contacts on the relay get damaged.
The relay contacts either 'weld' On or do not make a good contact.
Also if the light unit uses the linear type high wattage lamps, the lamp to end contacts corrode, so the security lamp will light sometimes not power On.

E
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
If the relay contacts are driving a high wattage lamp, say 400W/500W, I have found that the contacts on the relay get damaged.
The relay contacts either 'weld' On or do not make a good contact.
Good point. Just because the relay clicks when the coil is powered doesn't mean that a good contact is made. Unfortunately I don't have a suitable spare and getting one delivered would cost almost as much as a new fixture. I hate giving up but I don't see any sense in continuing.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
...I have found that the contacts on the relay get damaged.
You nailed it. I was giving up and then realized I had another security light in the junk pile. Turns out the relay in that one was a pin-for-pin replacement of the suspect relay. So I did the swap and sure enough, it works fine now. Yay, I saved a $15 item from the trash!
 
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