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I have 9 potentiometer with the specs: 10k Ohms and 0.5W

I'm using an Arduino Mega, and using it's 5V port output to power these potentiometers in series, and I saw online that the max current this board can supply is ~450 mA

So, if there are 9 10k Ohm resistors in series, the total resistance in the circuit is 90k Ohms. So, using ohms law I=V/R = 5/90000 = 0.0556 mA current will flow through the potentiometers?

And to find the maximum current each potentiometer can take, if I use I = sqrt(P/R) = sqrt(0.5/10000) = 7.07 mA.

So since only 0.0556 mA will flow through these potentiometers and each potentiometer can take up to a maximum of 7.07 mA (before overheating?), is this circuit totally perfect and all my calculations are correct?

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  • \$\begingroup\$ Thanks my IOS app.,does not display Latex in comments \$\endgroup\$ – Sunnyskyguy EE75 Feb 12 at 7:18
  • \$\begingroup\$ 56𝜇𝐴∗5𝑉=280𝜇W is long way from 500 mW –. Corrected from now obvious typo using my, fat fingers peek N poke on an iOS touch screen \$\endgroup\$ – Sunnyskyguy EE75 Feb 12 at 7:21
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You are just fine with the numbers you gave. With 10K pots you would need 70 volts across the CW and CCW pins or center tap to cause damage by heat, but at 50 volts the pots would get warm enough to have significant drift in value. As it is pots can have a drift as much as \$200ppm^oC\$.

At 10 volts they will stay close to ambient temperature, so ambient temperature will dominate any drift in value. Be sure the center wiper goes to a high resistance load or a buffer, even to drive LED's. LED's should always have a series resistor to limit maximum current flow.

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  • \$\begingroup\$ " Be sure the center wiper goes to a high resistance load or a buffer" means to check the datasheet and application notes for the pot that you are using. Allowable wiper current is often a SMALL NUMBER, requiring one to use a buffer (as @Sparky256 mentions) to protect the wiper contact. \$\endgroup\$ – Chris Knudsen Feb 12 at 13:05

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