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Old Jun 07, 2012, 07:28 PM
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Southern Vermont
Joined Feb 2007
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@psguardian, I could write it with a variable instead of calculated wire size as another calculation section But I'd have to know which variable you want to now calculate, since you aren't calculating wire size any more. It could be power supply voltage, or amperage, or wire length. But one would have to be chosen as the calculated value.

But the easy way is actually just to enter values for V, A and Length in the original spreadsheet, and just change them until you get .035 as the wire size. For instance, you probably already know what wire length you want. So that leaves voltage and amperage of your supply. If you've got an idea of what kind of supply you would like to use (automotive battery charger, or a 12V or 24 V transformer) you know the nominal voltage and the max permissible amps, so plug those values in and see what wire thickness you get. If it is smaller than .035 (probably is) turn down your variable control from 100% and watch the wire size until it's right.

Hopefully, you will be above 25% when the wire size is right. If not, consider using a lower voltage supply, like a 6 V transformer, battery charger, etc. It's better not to be too close to the bottom end of your adjustment - although probably do-able.

The whole purpose of this sheet is to allow people to size things so they will work together from the start rather than making trial and error purchases.
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