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

[Jarmo.Venalainen at schneider-electric.com]

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 
Phone: +604-422-2528  |   Tech Support: 800-670-0707  |   Mobile: 
+604-505-0291 
Email: jarmo.venalainen at schneider-electric.com  |   Site: www.Xantrex.com 
|   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 








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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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