Where can I buy a 9 Ohm Through Hole Resistor? - Page 1
Forum section: electronics / beginners

author: franklin19c
author_rank: Newbie
timestamp: May 14, 2020, 04:49:32 pm
content: I've been looking for hours trying to find a 9Ohm through hole resistor, and I can't find one. I may be missing something, but I don't even see them in the 100 piece sets on AliExpress or eBay. Any suggestions on where to look? There's a Microcenter near by, but I don't want to wait in line to get in the building with the restrictions going on right now.I'm trying to fix an cheap miltimeter with a fried resistor, so it's not really worth the trouble, but I'm just trying to find an excuse to work on something. I'm decent a soldering, but I'm new to actually repairing a board. Any help is greatly appreciated. I feel like this is a dumb question, so feel free to point and laugh. I just want to figure out what I'm doing wrong.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 14, 2020, 04:52:49 pm
content: You can use E24 value 9,1 R, but it definitely won't be as accurate.

author: schmitt trigger
author_rank: Super Contributor
timestamp: May 14, 2020, 05:03:04 pm
content: There are nifty freeware calculators, which will assist you in generating any arbitrary value with a parallel or series combination of resistor values.I am using ResCalc, but there are several others. And as long as you have your antivirus program up to date, they should be safe to use.

author: Nerull
author_rank: Frequent Contributor
timestamp: May 14, 2020, 05:04:51 pm
content: Are you sure its 9? That's not a standard value in any series AFAIK. Even Digikey doesn't stock any.They'll sell you some from Vishay if you wait 10 weeks and order at least 1000.

author: Benta
author_rank: Super Contributor
timestamp: May 14, 2020, 05:35:19 pm
content: 9 ohms is typical for multimeters, but are normally only available as complete, matched sets with 9, 90, 900, 9k etc.

author: Tom45
author_rank: Frequent Contributor
timestamp: May 14, 2020, 05:41:56 pm
content: Quote from: Nerull on May 14, 2020, 05:04:51 pmSince it is in a meter, the 9 ohms (presumably 9.0 ohms) is necessary for the accuracy of some meter range. The meter manufacturer would have special ordered, or perhaps custom made their own. At 9 ohms, it could be a hand made wirewound resistor using small gauge wire.Or use combinations of series or parallel resistors as suggested by schmitt trigger.

author: franklin19c
author_rank: Newbie
timestamp: May 14, 2020, 05:52:26 pm
content: I'm pretty sure it's a 9 Ohm, but I attached a couple pictures. The multiplier band looks to be silver, but that's where it was burnt most. The calculator that I was using shows 9 Ohm +/- .25%.There's a lot of space, so I may be able to hook a small series of resistors in there to get to 9ohm.I'm going to check out ResCalc now.I didn't even know about the E24 resistors. That sounds like it may work, I have some more reading to do...Thanks for the replies.

author: Benta
author_rank: Super Contributor
timestamp: May 14, 2020, 05:59:10 pm
content: Like I said, it's a typical "multimeter"-resistor.As a quick fix, two 18-ohm resistors in parallel will do the trick.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 14, 2020, 06:05:17 pm
content: ^^ As Benta said, two 18 Ohm resistors in parallel.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 14, 2020, 07:09:59 pm
content: I have to add - try to find 0.1% (18R 0.1%).

author: james_s
author_rank: Super Contributor
timestamp: May 14, 2020, 07:43:27 pm
content: Another option is buy a bunch of 9.1 ohm resistors and then go through and measure them until you find one that's as close as you can find to 9 ohms. You can buy 100 resistors for just a few dollars.The pair of 18 ohm resistors in parallel is probably less work though.

author: magic
author_rank: Super Contributor
timestamp: May 14, 2020, 08:38:19 pm
content: Alternatively, Dave used 2.2 + 6.8 to get 9 in the µCurrent.Quote from: james_s on May 14, 2020, 07:43:27 pmThat's more than 1% off so you would need some rather shitty resistors, I wouldn't put such crap in a DMM out of concern about stabilityThere is also the question how to actually measure a 9Ω resistor with <1% precision, it's not exactly straightforward without somewhat specialized equipment.By the way, the function of such resistor in typical 3.5 digit DMMs is the 20mA DC current range and IIRC other current ranges won't work too without it.

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 14, 2020, 08:50:27 pm
content: How about 9.1 ohms and 820 ohms in parallel? Or 10 ohms and 91 is pretty close to 0.1%.

author: Jwillis
author_rank: Super Contributor
timestamp: May 14, 2020, 08:54:39 pm
content: 9 OHM 0.6W 0.5% AXIALhttps://www.digikey.ca/product-detail/en/vishay-bc-components/MBB02070C9008DC100/MBB02070C9008DC100-ND/5060937Unfortunatley you have to buy a 1000 of them. Which sucksMight narrow down the product .

author: Zero999
author_rank: Super Contributor
timestamp: May 14, 2020, 10:12:09 pm
content: Quote from: Benta on May 14, 2020, 05:59:10 pmOr 4.3 and 4.7 Ohm or 6.8 and 2.2 Ohm in series. As mentioned above there are plenty of online calculators. Those are just some values which popped into my head. No doubt there are plenty of other combinations of two E24 resistors to give 9 Ohms.

author: Jwillis
author_rank: Super Contributor
timestamp: May 14, 2020, 10:47:01 pm
content: I know you specifically asked for through hole ,but why couldn't you use a surface mount. The vias should guarantee connection to both sides of the board.You could use something likehttps://www.digikey.ca/en/products/detail/vishay-foil-resistors-division-of-vishay-precision-group/Y17469R00000B0R/8624626The SMR3DZ has a length of about 7mm. It's not a conventional approach but it might work. They're pretty expensive still at $40It's an option

author: TimFox
author_rank: Super Contributor
timestamp: May 14, 2020, 11:01:00 pm
content: You could find a high precision 10.00 ohm (say, 0.1%) resistor and connect a reasonable 91 ohm (lower power and smaller) in parallel to obtain nominal 9.010 ohms. If the 91 is 5% low (86.45 ohms), you get 8.963. If 1% low (90.09), you get 9.001. Piggybacking a physically small resistor in parallel with a larger leaded part is usually simpler than series connection. What accuracy do you want?

author: rcbuck
author_rank: Frequent Contributor
timestamp: May 14, 2020, 11:23:27 pm
content: Mouser part numbers:279-YR1B10RCC 10 ohm, 0.1% $0.51 qty 1279-YR1B90R9CC 90.9 ohm, 0.1% $0.58 qty 1Parallel combination is 9.009 ohms +/- 0.1% (maybe less % if one is + and the other is -). They are 1/4 watt resistors which is what the old one appears to be.

author: Kirr
author_rank: Regular Contributor
timestamp: May 15, 2020, 01:02:13 pm
content: You can use this online calculator to build nominal 9 Ohm out of whatever stock you have:http://kirr.homeunix.org/electronics/resistor-network-finder/(For actual accurate 9 Ohm you may need to try and measure, and/or use 0.1% error resistors).

author: KingSolomon
author_rank: Contributor
timestamp: May 15, 2020, 02:42:50 pm
content: In addition to rescalc, digikey also has a whole host of calculators.https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-parallel-and-series-resistor

author: franklin19c
author_rank: Newbie
timestamp: May 15, 2020, 04:26:12 pm
content: Thanks again for all the replies and options.Since this is just a cheap multimeter that I'm working on, two 18 ohm resistors (which seem to be more common) in parallel is what I'm going to try first.

author: james_s
author_rank: Super Contributor
timestamp: May 15, 2020, 04:44:49 pm
content: Quote from: Jwillis on May 14, 2020, 10:47:01 pmI bet he could buy at least two of those multimeters brand new for the same price as that $40 resistor

author: bob91343
author_rank: Super Contributor
timestamp: May 15, 2020, 04:51:23 pm
content: I think I have a sack of 9 Ohm resistors. I will check next time I think of it.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: May 15, 2020, 08:18:39 pm
content: Quote from: franklin19c on May 15, 2020, 04:26:12 pmJust be aware that an 18 Ohm 5% resistor will be guaranteed to be at least 1% off, otherwise the manufacturer would sell it as a 1%'er. So look for one that's 1% low and one that's 1% high and put those in parallel. That should be very close.

author: magic
author_rank: Super Contributor
timestamp: May 15, 2020, 09:07:35 pm
content: That's not guaranteed and certainly not for 5% because the only small 5% resistors today are carbon film and with most manufacturers 5% is already the highest grade they offer.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2020, 12:44:19 am
content: Back in the days of carbon composition resistors, you could have used a 8.2 Ohm resistor, & a small three cornered file to tweak it "just right".

author: TimFox
author_rank: Super Contributor
timestamp: May 16, 2020, 01:47:09 pm
content: Instead of letting out the magic smoke, you would let in the healing moisture...

author: Gyro
author_rank: Super Contributor
timestamp: May 16, 2020, 04:17:10 pm
content: I seem to remember a dab of your wife's nail varnish being an essential part of the procedure - resistor filing, like fly tying, being a purely male pursuit.EDIT: Actually I think that was more on sold carbon resistors.

author: TimFox
author_rank: Super Contributor
timestamp: May 16, 2020, 04:48:20 pm
content: IIRC, you could also grind edges of disc ceramic capacitors to reduce their capacitance. (Try that with a MLCC!)

author: bob91343
author_rank: Super Contributor
timestamp: May 16, 2020, 05:43:49 pm
content: I was wrong. I have a sack of 1.9 Ohm resistors, not 9 Ohm.

author: bdunham7
author_rank: Super Contributor
timestamp: May 18, 2020, 04:46:52 am
content: Is that a DT-830 DMM?Do you have a more accurate DMM to help you select resistors? Two 18R would be the way to go, but if you are trying to be precise, you would want to measure the combo with a better DMM.

author: aries1470
author_rank: Regular Contributor
timestamp: May 18, 2020, 07:02:01 am
content: Not sure if anyone has brought this up.. but here's a link, but they are not 1%, and they are wirewound, but you can get them in single quantities.Mouser

author: Zero999
author_rank: Super Contributor
timestamp: May 18, 2020, 03:19:58 pm
content: Quote from: basinstreetdesign on May 15, 2020, 08:18:39 pmPerhaps 60 years ago but I no longer believe that's the case. 5% tolerance resistors tend to be made of cheaper materials such as carbon film which use a different process than 1% metal film resistors.

author: franklin19c
author_rank: Newbie
timestamp: May 22, 2020, 07:03:47 pm
content: FINAL UPDATE:Multimeter is working perfectly. The 18 ohm resistors I bought were much bigger, but I was able to put 2 in parallel and make it work. It's not pretty, but it works.Resistors measured 18.2 ohms, so the 2 in parallel were 9.1 ohm, but the measurements are very close to another multimeter that I compared the measurements to.Thanks again to everyone. I learned a lot, and it was fun.

author: TimFox
author_rank: Super Contributor
timestamp: May 22, 2020, 10:13:57 pm
content: If your two resistors measure to 9.1 ohms, that is a standard value for 5% tolerance resistors.

author: magic
author_rank: Super Contributor
timestamp: May 22, 2020, 11:26:21 pm
content: Quote from: franklin19c on May 22, 2020, 07:03:47 pmDid you take into account that 0.2Ω could easily be resistance of the test probes and cables alone?

author: TimFox
author_rank: Super Contributor
timestamp: May 23, 2020, 05:23:30 pm
content: If you don't have a four-terminal ohmmeter to remove the problem mentioned above, you can measure resistance with two DMMs: one in series to measure current and another across the resistor to measure voltage. Place the current at the ends of the wire, and the voltmeter across the resistor very close to the body for accurate results. You will be limited by the accuracy of the current measurement.

author: MarkF
author_rank: Super Contributor
timestamp: September 24, 2020, 09:16:22 am
content: If you decide to change out your two 18Ω resistors, Mouser has 9Ω 1% from Vishay/Dalehttps://www.mouser.com/ProductDetail/Vishay-Dale/RS1%5C29R000FE70?qs=sGAEpiMZZMvNd0dY0KymzuzWSQ9ynPoRBnvoju4%252BWFM%3DThey are 3/4W but still only 8mm long.

author: drussell
author_rank: Super Contributor
timestamp: September 24, 2020, 09:36:12 am
content: Quote from: MarkF on September 24, 2020, 09:16:22 amSure, but why would you buy a $4 resistor to repair a $3 multimeter?Any series/parallel combination that gets close will be more than adequate in this application.Personally, I would probably have pulled out a 9.1 and shunted a little 1/8W 1K across it since I have lots of those. Close enough. Probably way closer than the original resistor in an 830.An 820 ohm would be even closer.

author: magic
author_rank: Super Contributor
timestamp: September 24, 2020, 10:16:26 am
content: Quote from: franklin19c on May 22, 2020, 07:03:47 pm