In Reply to: 120Vac on a 115Vac transformer posted by danlaudionut on March 10, 2007 at 10:44:32:
I agree with Eli's post, but if you still feel that you must tweak the input voltage, you can use a smaller 120vac-to-5vac transformer as a bucking device. Connect the 5vac winding in series with the 115vac primary of your main transformer. Together these series windings are then connected across the full 120vac line. Hook it one way, and you'll get 125vac ("boost") across your main transformer’s primary, not what you want. Hook it the opposite way ("buck"), and you'll drop five volts almost losslessly, from 120vac to 115vac. You’ll need to experiment (measure) first. The 120vac primary of the buck transformer must be connected across the full 120vac line of course, of course. This approach results in much lower DCR than just sticking in a series dropping resistor.
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Brian
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Follow Ups
- Buck transformer - BBeck 11:37:24 03/10/07 (0)