Fast accurate measuring resistance ? - Page 1
Forum section: electronics / testgear

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 25, 2018, 04:04:15 pm
content: Hi, i have this aneng 8008 multimeter, i am measuring many resistors, it takes a lot of time with this multimeter.When you attatch the resistor the value goes down fast, then slower, then very slow, then still have to wait for the last change before i got a definitive reading.Suppose i buy a expensive bench meter, would you have a instant accurate reading ?, or how long does it take to compare ?thanks

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2018, 04:27:59 pm
content: You can fix a Ohms range manually on the 8008 and the readings will be very fast.(blue 'range' button)

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 25, 2018, 04:48:49 pm
content: I have only still have to wait long before the value goes down to the absolute value.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2018, 05:24:58 pm
content: In the good old days it would tell you the maximum autorange times in the manuals, not any more.The HIOKI DT4282 is supposedly one of the fastest handhelds.This guy spends ages using one to measure resistors from about 4:05 onwards. It's in Spanish but you can definitely see how fast it is:Probably about one second to get a stable reading for resistance.In other tests it's faster than a Fluke 87V:The DT4282 is a very good all-round multimeter. The only problem is the price: It's not cheap (especially compared to an ANENG 8008!)How much is your time worth?

author: radhaz
author_rank: Regular Contributor
timestamp: July 26, 2018, 03:04:05 am
content: Love my 4281

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 26, 2018, 10:59:12 am
content: Quote from: Fungus on July 25, 2018, 05:24:58 pmNot that much, it cost over 700€ wow.I will watch tv for 2 seconds while measuring then, i,m almost done with my resistors.What a coincidence i am also measuring 180K.And nice, that meter has a digit more then the aneng.Still not fast enough for 700 euro, i better buy a benchmeter for that ammount, only that dont combine with watching TV.

author: Fungus
author_rank: Super Contributor
timestamp: July 26, 2018, 11:12:10 am
content: Quote from: JanJansen on July 26, 2018, 10:59:12 amYou can get them much cheaper than that, maybe even under 400 Euro.eg.https://www.tequipment.net/HiokiDT4282.html(use EEVBLOG discount code)But no, not cheap.(Hey, you wanted the fastest!)Quote from: JanJansen on July 26, 2018, 10:59:12 amA Bench meter isn'tgaranteedto be fast just because it's a "bench meter".When you open them up you might find a handheld meter in a big box with a mains power supply, eg:The advantage of "bench" meters is that you can stack them, they don't move around when you pull on the wires, you can leave them on all day because they don't need batteries, etc. "Speed"? Not garanteed.If you're measuring 180K many times then just lock the range to 1MOhm. Your little Aneng should be fast enough.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 26, 2018, 11:15:10 am
content: I set the Kohm with the point before the last digit to measure the 180.0 K

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 26, 2018, 03:14:57 pm
content: There's definitely a way to go extremely fast, e.g.https://youtu.be/xbVYgyoIrRk?t=1194is a capacitance meter with equivalent-series resistance output that measures in milliseconds.

author: Kalvin
author_rank: Super Contributor
timestamp: July 26, 2018, 03:23:01 pm
content: Probably hacking those simple Transistor tester / LCR meter firmwares one could get very fast measuring times (well below 1s) with lead compensation, autoranging and sufficient accuracy.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 27, 2018, 03:55:44 pm
content: Quote from: Fungus on July 26, 2018, 11:12:10 amImport Cost: $136.30 from U.S.A.Maybe i can order from Japan soon, E.U. have made trade agreement with Japan, i hope no taxes if i order there.Only i cant read Japanese.€400,- i would buy it!

author: Fungus
author_rank: Super Contributor
timestamp: July 27, 2018, 04:09:28 pm
content: Quote from: JanJansen on July 27, 2018, 03:55:44 pmThere's one for 380 Euros on eBay:https://www.ebay.nl/itm/152968644340Are you feeling lucky with import charges?

author: bugi
author_rank: Regular Contributor
timestamp: July 27, 2018, 09:45:05 pm
content: Quote from: JanJansen on July 27, 2018, 03:55:44 pmSorry about this a bit longish off-topic, but these wishful thinking fellow EU members, I just have to... (This text is a bit extra-long as I don't know how much each reader might already know, so buffed it a bit, just in case.)The trade agreements usually mean that some/many products will be at 0%customs, but you'll still have to pay theVAT(including VAT for delivery/shipping cost). For most electronics (and other items) that I have been buying & importing, the customs has already been in 0-3% range, and I have just ignored those (meaning I pay them once the invoice comes, but I don't bother calculating them myself). It is the VAT at ~20%+ that needs to be considered, unless the item costs thousands, in which case the customs-cost might also be worthy of thinking about.And you will likely still have to declare the imports properly (or someone else would do it for you, like shipping company service), or how else would the customs know where the items are from or what items there are inside (just in case there are items that would still have non-0% customs, or which might have restrictions). Where the package comes from does not always equal the customs-% calculation country, and someone usually has to confirm the shipping document information, etc.Slightly simplifying, there is a very easy rule of thumb for consumers in EU: If you obey the laws, you will almost never avoid the VAT. It does not matter where the product was made (EU/china/japan/...), what agreements there are, which route it took, where and by whom it was sold it, etc.... The VAT will come in there at some point. When buying as a consumer within EU, the VAT is nicely calculated for us and included in the shown price (and the seller gives that VAT to government later). When ordering from outside EU, we need to calculate that VAT ourselves (and pay it separately). The exception is very low value orders, where many countries have threshold under which there is no need to pay the VAT, mostly because the bureaucratic costs for customs organization would be higher than the VAT the government would receive.And because the VAT hits at so much lower threshold than customs, having 0% customs via trade agreement does not save from certain stupidly greedy shipping company extra fees; one needs to pay those fees typically for the customs processing whether it is just VAT or both customs+VAT to be paid. And quite often those fees are higher than the customs+VATAnd the trade agreements don't affect those greedy companies.So yeah, no point in waiting for the trade agreement. When it comes, it will reduce the prices of some items a tiny bit, some rare things a bit more (there are things with higher customs-%, but I've yet to bump to one), and saves a lot of work at customs (it is much more work to get the customs-costs figured than figuring out the VAT). Those tiny price drops and less customs work means overall more trade, especially in the industrial level (which typically do not pay VAT to begin with, as the VAT is pushed towards the end-buyer), and that is what the governments and industries are after with the trade agreements.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 28, 2018, 11:38:24 am
content: Wait : then you pay in 2 countrys taxes ?, that is no trade agreement.I am willing to pay the ebay price and ebay shipping, nothing more.By the way i dont think this nice meter will work since i dont have climate control :today measuring 1% resistors to match 17 pieces with 1 digit accuracy ( 180.0 K ).It took all day and the weather changed, now my measurements are not good anymore, i was about to have 17 matched.edit : By the way : i measured all resistors already in advance, in bags from 178.9K to 180.0K, now i was only finding a match out of 17 from a sorted bag, rudely sorted because it took 2 days to sort all, temprature was changed for sure,all bags still had a wide difference today.Maybe those 0,1% resistors are worth the money.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 28, 2018, 02:49:32 pm
content: The temperature coefficient of resistors is also important. Tolerance isn't the only spec.When you export from another country, you usually do not have to pay sales tax in that country. Instead, you pay VAT in Europe. If you have to pay sales tax, it's most likely because the product wasn't exported properly (and sometimes it's just not worth the hassle).

author: Fungus
author_rank: Super Contributor
timestamp: July 28, 2018, 02:57:40 pm
content: Quote from: JanJansen on July 28, 2018, 11:38:24 amEven a 0.1% resistor has wider tolerance than 0.1 Ohms.Trying to sort resistors to that accuracy with a multimeter and ordinary probes is folly. The slightest variation in pressure and/or finger grease will affect the reading.At a minimum you need to do a four wire measurement.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 28, 2018, 03:17:34 pm
content: Quote from: KaneTW on July 28, 2018, 02:49:32 pmIts Yageo 50 ppmc 180K resistors.Quote from: Fungus on July 28, 2018, 02:57:40 pmI youtubed about 4 wire resistance, nice.It says it is only for very low values.I am measuring 180.000 ohms here, not below 1 ohm so i,m not sure if i need it.so it needs to be accurate to 1000 ohms, since the aneng 8008 cant have more then 4 digits.I cant have exact 17 matched to 1000 ohms accuracy,i do have a match of 3000 ohms ( 179.0K , 179.1K , 179.2K ), best i have so far after measuring 3 times.

author: Fungus
author_rank: Super Contributor
timestamp: July 28, 2018, 03:38:02 pm
content: Quote from: JanJansen on July 28, 2018, 03:17:34 pmYou can use it foranyvalues, it's just Ohms law.The point is that it removes the error introduced by the lead resistance and the probe contact with the resistor (voltage and current are immune to that at these sort of levels).The method is much more necessary for smaller values than larger value because the leads and contact resistances areverysignificant there.If you have 12V and another meter you can measure your resistors using four-wire - 12V should give about 66.66uA on your resistor which you can measure with the 100uA range on the AN8008.PS: You know you're trying to measure 0.1% accuracy with a meter that only has 0.5% +/- 3 count accuracy, right?

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 28, 2018, 04:04:23 pm
content: Its about the match not the value.

author: Fungus
author_rank: Super Contributor
timestamp: July 28, 2018, 04:12:09 pm
content: Quote from: JanJansen on July 28, 2018, 04:04:23 pmOK. Four wire measurements are your friend for that.

author: The Soulman
author_rank: Super Contributor
timestamp: July 28, 2018, 04:16:46 pm
content: Quote from: JanJansen on July 28, 2018, 03:17:34 pmThat is a 200 Ohms difference, ok if you consider rounding errors its max. 400 Ohms.If you want to match resistors to a high accuracy with minimum equipment you could use a wheatstone bridge.It's easy enough to diy, only needs three additional resistors, a voltage source, and a milivolt meter.

author: The Soulman
author_rank: Super Contributor
timestamp: July 28, 2018, 04:24:59 pm
content: It's described really well in part two of this series:http://conradhoffman.com/mini_metro_lab.htmlYou don't need a null detector for it to work.Quote from: Fungus on July 28, 2018, 04:12:09 pmNot really needed for such high values and at these inaccuracies.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 28, 2018, 04:34:11 pm
content: Thanks, i will take a look tomorrow.

author: tooki
author_rank: Super Contributor
timestamp: July 28, 2018, 10:46:39 pm
content: A used bench meter (a real one, not the crap like the Uni-T one Fungus showed the insides of) is not a bad idea. If you can find a Keithley 2000 series (like a 2000 or 2015), you'll be thrilled at how fast they measure.

author: Fungus
author_rank: Super Contributor
timestamp: July 29, 2018, 01:33:50 pm
content: Quote from: The Soulman on July 28, 2018, 04:24:59 pmThat doesn't solve anything, it just transfers the problem to measuring the potentiometer and the 'known' resistors instead of the resistor under test.What's needed for resistor matching is to eliminate tiny variations due to contacts, etc.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 29, 2018, 01:48:03 pm
content: It looks also complicated, and if i take a look at the youtube movie, i would have short circuit with a 2 ohm resistor.No i just want to measure ohms not volts, else they should have build that into the multimeter.For now i have my sets of 17 resistors, a whole lot, need to solder those first,by the time i need to measure more resistors i expect a aneng meter with 5 digits for 10 euro shipped on ebay.The 17 resistors are for a voltage controlled oscillator digital to analog converter.Every synthesizer voice needs 17 resistors, here i made a new topic about the resistors what i dont understand :https://www.eevblog.com/forum/projects/2-equal-resistors-is-not-the-same-as-1/

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 29, 2018, 03:15:56 pm
content: By the way : some shop dont sell hioki dt4282 anymore, so its old meter,i will see what model hioki releases next, intresting.

author: Fungus
author_rank: Super Contributor
timestamp: July 29, 2018, 08:48:49 pm
content: Quote from: JanJansen on July 29, 2018, 03:15:56 pmIt's very old-school construction inside - surface mount but not much integration - lots of 74XX logic and stuff.Doesn't make it worth any less though, I say there's no better time to buy one!

author: Synthtech
author_rank: Regular Contributor
timestamp: July 29, 2018, 09:16:34 pm
content: The Hioki DT4282 is very, very fast, it leaves my Keysight U1282a in the dust in terms of measurement speed and autoranging.

author: Fungus
author_rank: Super Contributor
timestamp: July 30, 2018, 04:01:29 am
content: Quote from: Synthtech on July 29, 2018, 09:16:34 pmIt's also 0.03% accurate on the Ohms range and measures up to 600MOhm. I don't think there's a handheld DMM that can beat those specs.

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 30, 2018, 02:16:06 pm
content: When measuring capacity ?, are there also small values ?

author: Fungus
author_rank: Super Contributor
timestamp: July 30, 2018, 03:02:17 pm
content: Quote from: JanJansen on July 30, 2018, 02:16:06 pmSpecs are here:https://www.hioki.com/file/cmw/hdInstructionManual/93344/pdf/?action=browserThe lowest range is 1.0nF with 1100 counts at 1%+/- 20 so that's around 1pF resolution.(ie. it beats the Fluke 87V and Brymen 869S here as well)

author: JanJansen
author_rank: Frequent Contributor
timestamp: July 30, 2018, 03:26:05 pm
content: That is really a nice meter,lazy politicians need to hurry the trade agreement.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 30, 2018, 07:16:36 pm
content: Customs duty is negligible, and VAT won't change. Just import it.