# small sealed 12VAC to 12VDC package



## tome9999 (Dec 16, 2009)

I want to use some cheap LED strings for a landscape application. My current landscape xfmr puts out 12VAC (actually near 14VAC to be accurate). Does anyone know of a small, 12AC to 12DC converter, sealed so outdoor use wouldn't be an issue?


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## lolzertank (Dec 17, 2009)

Four diodes or a bridge rectifier and a capacitor work well enough.


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## jtr1962 (Dec 17, 2009)

Besides a full-wave bridge and filter cap, some sort of circuit to regulate LED current is a must. You can even go with a simple resistor if it's only a few low-power LEDs.


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## tome9999 (Dec 17, 2009)

Thanks, so is there a pre-packaged package that is ready made to do this?

If not, what regulator (and surrounding circuit) should I build? Can I encase that circuit in epoxy or moldable plastic or something so water won't infiltrate?

Tome


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## Paul Baldwin (Dec 17, 2009)

Hi,
I made a lamp for a mechanic friend of mine about 12 months ago using the http://www.dealextreme.com/details.dx/sku.13555 driver. I potted it in epoxy resin to protect it from the elements. It's been used/abused and left outside ever since and still works 
Maybe a good start?

Paul.


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## znomit (Dec 17, 2009)

AC buckpuck?


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## tome9999 (Dec 17, 2009)

znomit said:


> AC buckpuck?



Now you're talkin' (I think) 

One of these: http://www.luxeonstar.com/buckpuck-350ma-ac-led-driver-with-leads-p-21.php

So, if I read that right, I can put 12VAC into it, and can drive a pile of LEDs. However, the output voltage claims 32VDC, won't that fry a string that usually operates at 12VDC?

Tome


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## jtr1962 (Dec 17, 2009)

tome9999 said:


> So, if I read that right, I can put 12VAC into it, and can drive a pile of LEDs. However, the output voltage claims 32VDC, won't that fry a string that usually operates at 12VDC?


32VDC is the maximum DC input voltage. As stated on the link:

_350mA true constant current output regardless of the number of LEDs connected to the driver_

So this would work fine whether you connected it to one LED or several in series.


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## spencer (Dec 17, 2009)

But it is a buck driver so the input voltage HAS to be more than the output voltage.


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## jtr1962 (Dec 17, 2009)

spencer said:


> But it is a buck driver so the input voltage HAS to be more than the output voltage.


Yes, that's definitely true. If the input is 5VDC then you can only run 1 LED. If it's 32 VDC then you can probably run 9 LEDs, possibly even 10 if they have a low Vf.


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## znomit (Dec 17, 2009)

I haven't been through the AC datasheet but the DC needs about 1-2V overhead. 
So for the OP this would mean 14V would drive what 12V is driving now.... assuming the current setup is just LEDs (_cheap LED strings..._ could be a few things), if its a string with a built in driver who know if it will work or not.


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## tome9999 (Dec 17, 2009)

znomit said:


> I haven't been through the AC datasheet but the DC needs about 1-2V overhead.
> So for the OP this would mean 14V would drive what 12V is driving now.... assuming the current setup is just LEDs (_cheap LED strings..._ could be a few things), if its a string with a built in driver who know if it will work or not.



I was thinking of buying a cheap xmas light string of led lights and cutting off the AC plug and voltage converter they have (or at least the ones I saw had) and driving the LEDs directly. I admit I don't know the LED specs but did see some 12VDC lights here:
http://www.imaginarycolours.com/Mer...193&Category_Code=12vStrings&Product_Count=13

That I figured might be similar...
Tome


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