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**To**:**Aquatic-Plants at actwin_com****Subject**:**Dupla Heating Cables****From**:**JOlson8590 at aol_com**- Date: Sat, 11 Oct 1997 09:51:49 -0400 (EDT)

There is yet another "solution" to the 42 volt power supply dilemma. _TWO_ (or more) transformers secondaries may be hooked in series (they MUST be "in phase!!!") to produce any given voltage. Thus, you could hook a 24 volt and a 12 volt transformer correctly, and get 36 volts. This is still under the 42 volt rating, but if you do the calculations, it will give you _significantly more_ heat. You could also hook 24 volt, 12 volt, and 6 volt transformers together and get 42 volts. Or, you could use two, 24 volt transformers, and get 48 volts. That could get you into trouble, because at that voltage you would be driving the cables a bit heavy. First, they might not handle the current safely, second, you are now at a high enough EMF to really zap yourself! (EMF = Electro Motive Force.) When hooking transformer secondary windings together, they MUST be "in phase," or instead of adding, they will SUBTRACT from each other. Not good. Also, you must consider whether the CURRENT ratings of all the transformer sec ondary windings are adequate, and whether the secondary windings are sufficiently insulated for the increased EMF. In this case, the 6-volt transformer would have a 42 volt EMF working quite hard to puncture the insulation. To try this, attach the PRIMARIES of the two transformers in PARALLEL, attach the secondaries of TWO transformers in series, then check the resultant voltage. If it is not correct, REVERSE the connections of ONE of the two transformer secondaries. Now it should be correct. Then, if you are connecting three transformer secondaries, check the voltage after adding the third. Same criteria, same solution. I am _not recommending_ any of these "solutions," just noting that "there is more than one way to skin a cat." (Or, you could just spring for the Dupla Transformer!! :-)) Cheers! Jean Olson JOlson8590 at AOL_com Out in the Boonies, near Cambridge, Iowa

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