Hello,<BR>A fellow forumite {k1tmj} tells Me I can make my own isolation transformer by stringing two low-voltage transformers together.So I went down to the electronic surpluss and bought two matching transformers.The secondaries are 12.8v, 2amps.I know I'm supposed to hook the secondaries together but am not sure what the correct way is.Do I go neg.to Pos.etc.,or Pos. to Pos. Etc.Also,Does this now make the primary of the second transformer become the output?This is a new one for Me I could use some of your wisdom.Thanks much!<BR>Phil<BR><P>------------------<BR>

Yep, that's the way. Just connect the outer windings on each secondary together. The primary of the second transformer then becomes the output. This setup should be good for about 25 watts.<BR>Curt<P>------------------<BR>Curt, N7AH

Yes, you just need to connect the two secondaries together. It does not matter if they are "in phase" or "out of phase"; either way of connecting the two secondaries is fine. Then, as you suspect, the primary of the second transformer becomes your isolated output.<P>The transformers you bought were actually a tad small for many applicatoins. With a 2 amp 12 V secondary winding, your transformers are only good for 24 volt-amps, which means at the 120 VAC isolated output, you can only supply 0.2 amp.<P>If you still have the receipts, I would return those transformers and get a pair of larger ones. You basically want the secondary voltage x amperage to be at least 50 for small radios, and more like 150 if you want to work on large radios or small TVs.<P>Tom<P>------------------<BR>

OOps!Since they're surpluss and therefore none returnable I guess I'm out ten bucks.Oh well.<BR>Thanks for the help.<BR>Phil <P>------------------<BR>

Phil, there are always a good selection of iso T's on Ebay, just do a search. The VIZ line of Isotap also let you adjust the voltage.<P>------------------<BR>

Try radio swap meets, I bought a nice large isolation transformer last year for $5.<P>------------------<BR>Bill Benson<BR>Bill267Benson at wmconnect dot com

Phil,<BR>Fair Radio Sales once had(probably still do) a ton of suitable transformers for making your own home brew isolation tranny.<BR>I had great results with two of them at about $8.00 each.<BR>My set up handles about 150 watts,and as I built it myself from all new components,I know it is dependable.<BR>Mine has a fancy polished aluminum control panel with pilot light,AC voltmeter,fuse holder and is mounted on a finished wooden base.<BR>A white(for high visibility among all the cords on the bench)extension cord was cut in half,and the male end used to feed the transformer while the female end feeds the set under repair.<BR>I didn't have a suitable toggle switch at the time and used a regular wall switch in a wall box which is mounted behind the control panel on the wooden base.<BR>Because the transformers are heavy duty (surplus)units,the whole deal runs as smooth,cool and quiet as a mouse taking a mid-day nap. <BR>It was fun to build and a "store bought"one would not have provided the satisfaction this one does.<BR>Malcolm Leonard<P>------------------<BR>