[RE-wrenches] Low wattage 120vac to 24vdc transformer for LED's

[Phil Undercuffler]

I've picked up used laptop or printer power supplies at Goodwill or the
local electronics recycler for a couple bucks.  Take your reading glasses
with you, and look for one with an output in the 24-30v range.

Phil

On Thu, Jan 29, 2015 at 11:08 AM, <Jarmo.Venalainen at schneider-electric.com>
wrote:

> Hi:
>
> For such a small amount of power you could consider using an energy
> limiting Class2 transformer as is/was used in old doorbells.  You would
> have to put a bridge rectifier and bulk capacitor on the output to make DC,
> but that should be ok given the power levels.  If you do this, make sure
> that the bridge rectifier and capacitor are physically very close to the
> transformer to reduce problems with diode reverse recovery losses which can
> stress the parts.
>
> Here's a link to Hammond transformers of that type, although they are no
> doubt available from many sources at most electrical supply houses.
>
> http://www.hammondmfg.com/ba.htm
>
> JARMO
>
> _____________________________________________________________________________________
>
> * Jarmo Venalainen*  |  * Schneider Electric **  |  Xantrex Brand*  |
> *CANADA*  |   *Sales Application Engineer*
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>  From: "Dave" <dave at independentpowerllc.com> To: "'RE-wrenches'" <
> re-wrenches at lists.re-wrenches.org>,  Date: 01/29/2015 10:58 AM Subject: Re:
> [RE-wrenches] Low wattage 120vac to 24vdc transformer for LED's Sent by: "RE-wrenches"
> <re-wrenches-bounces at lists.re-wrenches.org>
> ------------------------------
>
>
>
> We are renovating a 25 yr old off grid house and one of things being done
> is to change some 24vDC circuits to 120vac. The only problem that I'm
> having is finding a low wattage 120vac to 24vdc transformer for a few
> strings of 24v LED night lights (a few watts each string) that are built
> into some nice hardwood trim in the bedrooms.
> I just tested the following device and found that it uses 29 Watts to
> power a 3W LED. Not an acceptable load for this house. It is labeled as LED
> Magnetic Transformer by National Specialty Lighting part #
> TR24L20DC-M20L24DC-AR Input: 120vac, Output 24vdc, Maximum 20W
> Is there anything else available that will do this job and use a lot less
> power than 29 Watts?
>
> Thanks,
> Dave
>
> David Palumbo
> Independent Power LLC
> 462 Solar Way Drive
> Hyde Park, VT 05655
> 802-888-7194
>
>
>
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