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Old 07-22-2009, 11:37 PM   #492 (permalink)
MPaulHolmes
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Hello! You are using the HF volt meter, so you have to put it on the 200mV setting. Now, it will show numbers from 0 to 200, where 200 means 200mV. What I did was choose the length of copper so that 400 amps corresponds to 100 on the volt meter, so that it was like a %. So, for example, 50 means 200 amps.

Let's say you want to measure 0 to 400 amps. And you want a reading of 100 on the volt meter to mean 400 amps. You would do this:

V = I*R
0.1 = 400*R
0.00025 = R

So, you need 0.00025 Ohms of resistance. 00 gauge wire has 0.0779 Ohms of resistance per 1000 feet, so the length you need is...

0.00025 Ohms*1000 Feet/0.0779 Ohms = 3.21 feet of 00 gauge wire.

Or, 3 feet 2.5 inches.

ya!

If you want it to measure 500 amps instead, change the 400 above to 500. If you want the volt meter to read from 0 to 200, then change the 0.1 above to 0.2.
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