resistors

[malook]

Can I get some advice regarding wattage limits to use across some single resistors ( the little ones from an electronics store all under 100ohms).The component label suggests 0.5W,however, we have just purchased some new resistors but they burn out very easily when the students give them too much juice, so to speak.My understanding is a bit sketchy.

[dime]

I too would like some advice about resistors, if anyone understands them. Our old ones 2, 5 and 10ohm ones seem to be burnt out. We have the sliding variable ones too, which are fine, but the teacher wanted known resistances like the old ones. So I was looking at purchasing new multi-ohm ones but they are $80 each and not sure if they would last any better. Anyone out there got good ones or advice for the best way to go, please?

[Ocker]

The average small resistors are only 1/4 W, the best idea is to buy ceramic resistors.
They charge about 40c each for 5 W and about $1.80 for 10W
What I do is buy double the resistance value I need and wire 2 together in parallel this halves the resistance but doubles the wattage
Therefore I get a 10W for 80 c also when you order 25 or more from Jaycar the price drops to 27c each

[RosalieM]

I order from wiltronics. they have a little wooden bit on them with colour codes to work out their resistance. From memory it was about $4 for about 1000 so they are pretty much single use only (but if they are still working they go back in the bag). I bought a variety a few years ago and keep them in ziplock bags with the resistance written on it. I still have heaps left. I found the ceramic ones got broken too easily by kids being rough or dropping them.

[linotas]

Jaycar have multi resistor wheels for about $30 from memory.

[Ocker]

Yes but they are only 1/4W

[linotas]

Hmmm so they are. I know very little about electronics, but they work OK in our school.

[dime]

Thanks guys

[malook]

Thanks all,
I went with Ocker's idea and that seems to be working for us at present.

[Ocker]

See me "take a bow'