Resistor wattages, does it mater if I go bigger?.... Please

Tman · Post by **Tman** » Tue Nov 14, 2006 2:54 am

Hi im having trouble getting .25 Watt resistors. Will it be ok to use .5 Watt resistors of the same value in there place ? Im assuming this will not affect the operation of the board, it will just mean that they happen to be bigger than they need to be.
Sorry Im not very cluded up,

Cheers
Timon

Post by **brentp** » Tue Nov 14, 2006 3:12 am

That is suprising, since 1/4 watt is an extremely common size. Especially for the values specified- 100, 1K, 270, 680 ohm.

Electrically, 1/2 watt is fine- however, you are going to have problems getting them into the board since the holes are sized to fit a 1/4 W resistor. You're working with a board that has plated-through holes, drilling them bigger might cause problems.

I would really try to stick with 1/4 watt. Again, I'm very very suprised you're having problems finding them. Perhaps someone else in the UK can point you in the right direction?

I haven't done the math, but I would think that 1/8 watt resistors would work as well.

I hope this helps-

MartinM · Post by **MartinM** » Tue Nov 14, 2006 7:52 am

If you want to send me a stamped addressed envelope I'll stick some 1/4W resistors in it for you! email me srenellim (at) moc.liamtoh (both parts backwards!) for contact details

Tman · Post by **Tman** » Tue Nov 14, 2006 9:31 am

Yea its just the local shops dont stock them cos they never sell enough of them, and to get them on line I have to buy a pack of 10 for each size and pay shiping, which ends up being a bit of a silly price. Even tryed tv repair shops but the best i could do there was mixed and matched sizes from what looked to be very old stock. But there was one shop that stocked a good selection of .5W resistors. There the same physical size as the .25W but they are blue instead of tan, and the colour codes are differant?, (e.g.for the 100 ohm resistor colour is Blue, band colours are, Brown, Black, Black, Black, Brown) dont know what the all means, but the packaging assures me there .5W and the resistances I want.
Oh and Im in New Zealand

MartinM · Post by **MartinM** » Tue Nov 14, 2006 11:42 am

If they're the same size and you're sure they are the right value (double check them with a cheap multimeter) then they will be fine.

...unless you really want to send a SAE all the way to the UK!!!

Tman · Post by **Tman** » Tue Nov 14, 2006 11:59 am

Cool thanks for the help guys

Oliver Sedlacek · Post by **Oliver Sedlacek** » Tue Nov 14, 2006 12:57 pm

A 1/4 watt resistor rated at 70 deg C may be rated at 1/2 watt at 25 deg C

Autosport Labs

Resistor wattages, does it mater if I go bigger?.... Please

Resistor wattages, does it mater if I go bigger?.... Please

That is suprising, since 1/4

If you want to send me a

Yea its just the local shops

If they're the same size and

Cool thanks for the help

Could be specmanship