OK here is what to do.
First, measure the current on the B+ line you want to place the dropping resistor into.
Now using Ohm's law solve for R. R=E/I ..... Plug in the current (I) in AMPS and the voltage you want to drop (E) in volts (60) and the solve for R (the resistance needed).
So lets assume 500ma is the measured current, the equation would look like this:
R=60volts /.5 Amps so R=120 ohms
Then to figure out how many watts the resistor needs to be use P=IE Where P the power in watts = the current (I) in AMPS times the voltage drop across the resistor E (which in this case is 60 volts)
Lets assume the following for the Power equation
P (watts) = IE so P= .5 Amps * 60 volts Therefore P=30 watts
No guesswork needed if you know the current flowing and the voltage drop needed.
The value of the resistance will not likely be a standard value, so get one of those tubular ceramic types with the adjustable slider band so you can adjust to the needed value.
Good Luck!
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Last edited by ohohyodafarted; 12-25-2010 at 02:02 PM.
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