.1% resistors

[tryonziess]

is there a more selective source for precision .1% resistors than digikey and mouser that will sell 10 or 20 units. is the metal film the best choice for nationals 3886 gainclone. need help here i do not need 1000 resistors!!!!!

[richie00boy]

Why do you need 0.1% precision? If you buy a few normal 1% types off the same line they tend to be quite close anyway.

[Conrad Hoffman]

I always buy the 200 pc bags from Digikey for about $8. If I need to select, it's easy to sort out a bunch of matched parts to whatever tolerence I need, sometimes way beyond .1%. I can't stand to pay the much higher price for smaller quantities.

[phn]

Are the 3886s you have matched within 0.1%? If not, then you probably shouldn't worry too much about the resistors.

[scottw]

If you are doing a parallel or bridged-parallel amp then the 0.1% are necessary-see National Semi's AN-1192 (application note). If you are just doing a single chip per channel then they're not required.

If you need small quantities of 0.1% you can try Parts Connexion; look for the "Draloric" resistors across the bottom of the page:

http://www.partsconnexion.com/catalog/resistors.html


These come in 0.1, 0.25 and 0.5%.


Scott

[dfdye]

Originally posted by phn
Are the 3886s you have matched within 0.1%? If not, then you probably shouldn't worry too much about the resistors.

As Scott said, it definitely depends on the application. Based on what I have seen, the margins on the LM3886's are well past 0.1%, making B/P applications require the higher precision matching required for those applications to work well.

If you have some chips that are off greater than 0.1%, I for one, would love to hear about it. And then I am sure National would love to hear about it so that they can get you are genuine part or a replacement for a bum chip.


PS, I concur with the crowd that you should buy a bag of standard 1% resistors and match parts yourself. Within a batch, they are typically quite close to each other. Well within 0.1% typically. For the few parts you will need, you should be able to do this within a few minutes.