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Swapable DC string lights with photo sensor

Yoruai

New Member
Is it possible to wire a standard two wire light string to a DC controller box and still utilize the timer and photo sensor features?
I purchased this to go outside my wife’s room at the nursing home for Christmas. Since covid we aren’t allowed inside so it needed to be battery powered and weatherproof. Since it has a timer triggered by a photo sensor it’s also very efficient. Ran almost 3 months on three D cells.
I’m hoping to be able to change the lights out to run holiday appropriate colors throughout the year or just purple, her favorite color. The light string itself however has four wires (another two go out separately to the photo sensor). I suspect the extra two wires on the lights carry the signal for the timer/sensor. Unfortunately I’m not finding any stand alone string lights with four wires I could swap and crimp 1:1.
Can I somehow hook up a standard two wire string and cap or jump the other two or would I have to pretty much make my own string with 4 wires?
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rjenkinsgb

Well-Known Member
Most Helpful Member
To me, it looks like the lights are arranged in three strings or chains, to allow different colours or flashing patterns & sequences?
One common positive power connection (VCC) and three separate returns that each have the negative switched to control them; LD1, 2, 3.
The CDS1 terminals look to be for a light dependant resistor, the photosensor.

The big problem with trying to connect anything else, is that any lights you connect must be able to run from the battery voltage and not take too much current.

Light strips are readily available that use similar connections - but the commoner types operate on 12V and need a lot of current.
There are a few types made for battery powered devices however.

Examples - these types of strips could probably be wired to your controller:

If you look at any others, be sure it says they work from a three cell battery box.

I'd guess you may be able to make your own, but each LED in each string would need an appropriate resistor to allow it to work from between 3 - 4.5V over the life of the batteries, and the total current for all LEDs in each string no more that probably 100 - 200mA, depending on how often you are willing to change the batteries.

If the current is too high it may damage the tiny transistors that control the outputs, as well as draining batteries quickly.
 

Yoruai

New Member
That sounds promising. Thank you for the reply.
If I get one if the 4 wire versions of what you’ve suggested, you think it will retain all the features of the box beyond on and off if connected correctly?
Since there’s not likely to be a diagram, some experimentation will be required. Would you recommend putting a resistor between the connections as I test them to lessen the chances of burning something out in the controller? Or at power levels that low am I probably ok as long as I don’t leave them connected more than a few seconds?
 

rjenkinsgb

Well-Known Member
Most Helpful Member
The LED tape connections should be labelled positive, red, green and blue & connect directly to VCC (positive) and the three LD outputs, with everything working pretty much the same as before other than light sensing.

I'm about 90% certain it will "just work"..

Add an LDR (cadmium sulphide photocell) across the CDS terminals and the light sensing may work as well. eg.
 

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