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Outdoor LED Kit for Deck

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xmas111

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Hi guys,

I bought this outdoor led lighting kit from Lowes the other day to install in my deck.

Outdoor LED Kit

The transformer output is 12 VAC which goes to the photocell then 12 VAC to the LEDS.

My question is..... is there any way to add a dimmer some how to this setup?

I know there's a bunch of PWM dimmers out there but they all seem to work on DC voltage.

Or do you think I could use a 12 VDC power supply in place of the 12 VAC transformer? Then use a PWM dimmer?

The LEDS work great but 'dI just like to tone them down a little.

Any help would be appreciated.

Thanks,
John
 

Syncopator

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It may be possible, but unless you know what's going on inside the power supply box it's impossible to say.

If the 12Vac input is full-wave rectified and smoothed, then the resultant d.c. will be around 17V, so 12V may or may not work.
 

KJ6EAD

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PWM may be possible after the sensor but perhaps overkill. The sensor housing probably has at least a reverse blocking diode and maybe a complete rectifier. You could knock the LED current down with a resistor (1-5Ω 1W or 10Ω 2W) or just add a few power diodes in series (1N4001-7 or similar).
 

xmas111

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Maybe I described it wrong or I'm not understanding.

The voltage from the sensor to the LEDS is 12 VAC.

So I guess each LED assembly has a rectifier in it or maybe two LEDS back to back.

John
 

KJ6EAD

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The voltage from the sensor to the LEDS is 12 VAC.

So I guess each LED assembly has a rectifier in it or maybe two LEDS back to back.

That may be, but the same solution can be applied in any case, just make it bilaterally symetrical for both wires. It depends on what level of control you're hoping to achieve. If you want a fixed attenuation, just install it at the source. If you want to be able to vary the brightness from time to time, you need to add an intermediate box of parts (PWM circuit, diode attenuator or resistor attenuator) with switches or knobs. There's a good chance that your LEDs will dim significantly on their own with use anyway.
Solid-State Lighting: Lumen Depreciation
 

xmas111

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Ok, thanks KJ6EAD. If it ever stops raining here, Boston, I'll head out and try your suggestion.

Thanks again. I'll let you know how it works out.

John
 

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