In article ,
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In article MPG.1bd65c6ac2a9eb7f989682@news-server, ty1xlnf02
@sneakemail.removethis.com says...
...

Even though I don't have much electrical engineering experience, I'm
open to trying some of the DIY options I've read about. Anybody have any
recent experience with that? Anybody know of any good places to get low
voltage/high current (24 V @ 11+ A) step down transformers?



Tortran ( www.tortran.com ) makes nice toroidal transformers in that range. They
have a 300VA version and another at 500VA. (VA and watts are equal for a heater.)
These have two secondaries of 12V each, so you would connect them in series to get
24V output. The 500VA model is only $67, but comes without a box or anything, just
a large transformer with wires brought out. If you want to put one in a box
(recommended to protect your connections from getting wet) be sure to get the
mounting hardware.

If you like ebay you could possibly find one there too. 120V input, 24V output
transformers with high current ratings are fairly common.


George,

Here's my thread with a contact at Tortran:

Me "I'm interested in using some 250 watt 24 V substrate heating
cables for my aquarium and I need a step down transformer to power the
250 watt cables where the primary is 115V 50-60Hz, 2.9A and the
secondary is 24V Max, 12.5A and the windings are completely isolated
from each other. Do you sell anything like that? If so, could you let me
know what the price is? Thank you for the information."

Tortran Rep "Hello Allan, thank you for your inquiry. We have two
alternative designs for your consideration.

P/N B300-2 at $39.95
P/N R300-2 at $100.75

Prices are FOB factory in Bridgeport, CT.

These are both 300VA (24V at 12.5A) transformers. They come with dual
12V secondaries that you connect in series to get 24V. The R-model is
mounted inside a box and has a resetable fuse. If you go to our website
and click on standard transformers and then on lamp transformers and
scroll down you will see an illustration of the enclosed version for
remote installation."

After going to their website, I'm trying to figure out what is
contributing to the $60 dollar difference in price between the B and R
models. It looks like the R model has the following description:
Transformers mounted inside a white steel enclosure with automatic
circuit breakers for remote installation. Enclosed transformers are UL
listed. Input voltage 120V/60Hz. Single output voltage 12V under 300W
and dual 12V For extra safety we have added auto-resettable thermal
cut-offs inside the transformers between the primary and secondary
windings.

Is that worth the extra dough, or would it be easy enough for a layman
to by the bare transformer and build a box with $15 worth of Radio Shack
components?

Thanks again.