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I've heard of people saying they use potentiometers rated at 2W or more for a bias circuit. I think that's way overkill. Or is it?
Let's say we have a 50K linear resistor and the voltage across the pot is 43V (in my case with a 620R Rk).
According to ohms law P=E^2/R
I get P=43X43/50k = 36.98mW
With a safety factor of 2 it would be 73.96mW.
So you can even have a pot rated for 100mW and it would be more than double the safety factor. Any reason why someone would go with a pot that high in rated power? The smaller pots are much smaller and inconspicuous. But more importantly even a 100mW pot is above the safety factor.
Of course it depends on the circuit and voltage variance between bias circuits. But I can't see anyone needing 2W potentiometers. Of course it doesn't hurt though if you have alot of space in the chassis. Where I think I would go higher too.
Let's say we have a 50K linear resistor and the voltage across the pot is 43V (in my case with a 620R Rk).
According to ohms law P=E^2/R
I get P=43X43/50k = 36.98mW
With a safety factor of 2 it would be 73.96mW.
So you can even have a pot rated for 100mW and it would be more than double the safety factor. Any reason why someone would go with a pot that high in rated power? The smaller pots are much smaller and inconspicuous. But more importantly even a 100mW pot is above the safety factor.
Of course it depends on the circuit and voltage variance between bias circuits. But I can't see anyone needing 2W potentiometers. Of course it doesn't hurt though if you have alot of space in the chassis. Where I think I would go higher too.
