1/4w or 1/8w restistor

[darrenw6000]

I think we've all been there...nearly finnished a build and youre 1 resistor short, you have it in 1/8W but unsure whether or not to use it...my question Is it OK to use either wattage in a build. I always thought maybe effects that require more than 9v should use 1/4W no matter what. Could somebody  clarify this for me thanks.

[m-Kresol]

that depends. If it is for example the small (often 33R-56R) filter resistor in the DC supply circuitry, I wouldn't use a 1/8 W resistor as all the current demand has to pass there. For resistors in the audiopath it will be most likely ok to go with a 1/8 W resistor.

It would help to know which project and resistor you are talking about, so we can give you an answer on that.

[midwayfair]

Is there a voltage drop across the resistor? Do you know its value in  Ohms? Then you can apply Ohm's law to determine the current through the resistor and from there the power formula to determine the wattage required.

[darrenw6000]

I will work out the current then I can multiply by the resistance to get the power

[m-Kresol]

yep, that will work too of course. P=U*I=I^2*R