Want: 0.01% Resistors - Page 1
Forum section: electronics / general

author: Wh1sper
author_rank: Regular Contributor
timestamp: April 24, 2014, 08:45:39 am
content: For the purpose of self calibrating my Philips 2534 I'm searching for 30R, 300R, 3K, 30K, 300K and 3M Ohms 0.01%I've found some for 14€ Euro each which is a way to high for me.Has anybody an idea where I can find those?I've hope that 3-5€ should be enaugh for one.Whenever you can offer only a few of them I'm strongly interested.Regards

author: Kjelt
author_rank: Super Contributor
timestamp: April 24, 2014, 08:51:12 am
content: Why not make them yourself if it is for occasional calibration only? Ofcourse you need access to a calibrated meter.

author: Wh1sper
author_rank: Regular Contributor
timestamp: April 24, 2014, 09:00:57 am
content: Thats the point....None, I mean absolutly nobody in my realm be it physically our in the term of frienship has one.

author: max-bit
author_rank: Frequent Contributor
timestamp: April 24, 2014, 09:47:22 am
content: http://www.ebay.pl/itm/VISHAY-0-01-VSRJ-RS92N-Metal-Foil-Resistance-Resistor-100-200-5K-10K-Ohms-/291125244302?pt=FR_YO_MaisonJardin_Bricolage_ElectroniqueComposants&var=&hash=item43c86ab18e

author: jpb
author_rank: Super Contributor
timestamp: April 24, 2014, 09:47:29 am
content: You can build accurate 10:1 dividers yourself using the 3 matched Rs in parallel and matched to another Rb then the the three Rs in series is 9 times Rb so Rb is 1/10 the total resistance.This means you might get away with one expensive 0.01% resistor, a 10:1 divider then use it to make the other ones yourself (using trimmers).You can use your meter to do the matching as it doesn't need to be calibrated to match Rs, just give consistent readings (or you could use a bridge circuit).A further thought, if you matched a second resistor to Rb then you could have a bridge with (3Rs+Rb) in series with the second Rb on one side, the known R (0.01%) in series with the one you're making on the other and trim until balanced. You can thus go from R to R/10 and so on though I guess errors would mount.To get around the cumulative errors, or at least get a check, you could perhaps get two 0.01% resistors one at each end of the range then you could work in both directions and compare your final home-made with the known good value.

author: Wh1sper
author_rank: Regular Contributor
timestamp: April 24, 2014, 10:56:00 am
content: Quote from: jpb on April 24, 2014, 09:47:29 amYes it's the second best option.These two links are already in my portfolio :-)http://conradhoffman.com/HamonResistor.htmlhttp://www.gellerlabs.com/752AJunior.htm

author: Wh1sper
author_rank: Regular Contributor
timestamp: April 24, 2014, 10:56:38 am
content: Quote from: max-bit on April 24, 2014, 09:47:22 amOhh, didn't find it by myself, thanks.

author: Dago
author_rank: Frequent Contributor
timestamp: April 24, 2014, 11:52:45 am
content: Just buy 0.01% resistors off Digikey or whatever supplier you prefer? Loads of them starting at 1.15€/each from Digikey (only one I checked) at least:http://www.digikey.fi/product-detail/en/RNCF0805TKT20K0/RNCF0805TKT20K0CT-ND/2687088

author: mariush
author_rank: Super Contributor
timestamp: April 24, 2014, 12:49:46 pm
content: Farnell has 0.05% resistors for 0.25-0.4 euro a piece. 0.02% are a bit more expensive. 0.01% ohm resistors are indeed 10+ euro. In theory, you can put several 0.05% resistors in parallel to get the percentage better without raping your wallet... ideally, in practice i found most tend to be above or below the resistance value, it's hard to pick 10 for example and be sure the average will be closer to exact value/10 you want.Seehttp://de.farnell.com/smd-chip-widerstandehttp://de.farnell.com/widerstande-fur-durchsteckmontageFilter by tolerance you want, exclude extended range/USA import from the left side menu (you don't want to pay bunch of euros to have a few resistors shipped from US to you), then sort by price and ignore the 0 ohm resistors.

author: Wh1sper
author_rank: Regular Contributor
timestamp: April 24, 2014, 04:51:15 pm
content: Quote from: mariush on April 24, 2014, 12:49:46 pmHhm follow the second THT link and do as described I've got 1.xx € but only 250R, not more values, but thanks your tip I'll do a bit more searching...Ahh SMD is the key, but they are a bit worse @tempco