RESISTORS

DJQUIRK · Joined: Aug 07, 2006 Posts: 39 Location: ATLANTA GA

Is the wattage of a resistor like the voltage of a cap in that you just want the wattage of the resistor higher than the circuit with ever experience. In my search for pots for my sounlab I found a 100pc. lot at 100k but they are 1/2W, will they work??Thanks.

blue hell · Posted: Mon Aug 07, 2006 9:43 am Post subject:

Correct, you can calculate what you need with :

P = V * I and V = I * R , first one implying I = V / R and so P = V * V / R

or for 100 kE pots of 1/2 W :: V*V should be less than 50.000, or V < 220 Volts or so.

DJQUIRK · Joined: Aug 07, 2006 Posts: 39 Location: ATLANTA GA

THANK YOU

Uncle Krunkus · Posted: Mon Aug 07, 2006 6:08 pm Post subject:

The thing to remember with all electronic components is that as their power rating increases, so to does their size. (and their price, but I'll assume they were a bargain bulk lot) An over rated component takes up more room because there has to be a way for it to dissipate the extra heat. That usually means more surface area.
In the case of your 1/2 watt pots this is not an issue, because the case is only about 24mm across and these should fit in to most DIY projects fine, you need some room around the controls to operate them easily anyway.
It's the same storey for the voltage rating of caps, and the wattage of fixed resistors. If they physically fit into the space they have to go then you can over-rate anytime you like.