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 Safe resistor wattage calculation

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Cliff Jones
Site Administrator
Site Administrator

Join date : 2010-11-22

PostSubject: Safe resistor wattage calculation   April 10th 2018, 4:15 pm

Calculate the MAXIMUM Safe current through a resistor.


Joe has a 1.8K ohm resistor and it's rated at 0.5w

What is the maximum safe current through this resistor?

Let's use the formula P =  I X R^2

But let's rearrange the formula.

I = √P / R

So  √P/R = I

.5 / 1800 = .0003

√.0003 =.   .0167A  or  16.7mA

So with this formula Joe has determined that ½ watt resistor is safe for His application.

Easy enough right?

I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!
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