best probes you have? probe resistance - Page 1
Forum section: electronics / testgear

author: ftransform
author_rank: Frequent Contributor
timestamp: June 02, 2013, 05:04:43 am
content: What is the resistance of the best probes that you have? I have a no-name Chinese brand of probes that have a ~12miliohm resistance per leadthey came with a old ass radio shack metermy uni-t probes are like 30 miliohms per lead.

author: nctnico
author_rank: Super Contributor
timestamp: June 02, 2013, 11:48:29 am
content: First define best probesI have these probes. They are not low resistance (about 0.3 Ohm per lead) but they are incredibly handy for probing around in SMD circuit. Sometimes I also use them to power a circuit through the grabbers.

author: robrenz
author_rank: Super Contributor
timestamp: June 02, 2013, 03:01:52 pm
content: You seem to be looking at low resistance as you metric, so my best is 0.00000 Ohms as shownin this thread

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 02, 2013, 04:12:22 pm
content: mine ar pomona , fluke alike , and the silicon is so good !Robrenz , 0.00000 ?didn't you meant 0.0000014XXX or so ?LOL

author: robrenz
author_rank: Super Contributor
timestamp: June 02, 2013, 04:35:36 pm
content: A set of kelvin probes basicaly eliminates lead resistance.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 02, 2013, 04:42:55 pm
content: I know that , I meant to the total eror within that measurement methos , assuming you are 1uM far from the resistor , there you go , some 1uohm or so is added ,you must use 4 wire to eliminate any thing possible ( 4 wire resistor )

author: robrenz
author_rank: Super Contributor
timestamp: June 02, 2013, 04:47:33 pm
content: The implied question of the OP is lead resistance not measurement variation/error. I stand by my 0 ohms

author: AndyC_772
author_rank: Super Contributor
timestamp: June 02, 2013, 04:55:24 pm
content: 3 sets of different Fluke leads (loop resistance measurement with probe tips firmly pressed together):0.075 Ohm0.107 Ohm0.086 OhmLeads that came with my '830' budget DMM:0.055 Ohm, though a good contact is tricky to ensure.Maplin 'super high quality professional' or some such nonsense:Anything from 0.27 Ohms to 12 Ohms depending on orientation, pressure, weather, or what music I have on in the background

author: Lightages
author_rank: Unknown
timestamp: June 02, 2013, 05:13:21 pm
content: The best I have right now are around 0.033 ohms per lead. The worst are around 0.055 per lead. There will be much more info soon when I do my multimeter lead comparison/shootout.

author: BravoV
author_rank: Super Contributor
timestamp: June 02, 2013, 05:16:00 pm
content: Assuming the DMM has the nulling feature and still in the context of 2 wires measurement, really don't see whats the point of these lead's resistance, just for bragging / e-pen contest ?

author: Lightages
author_rank: Unknown
timestamp: June 02, 2013, 05:26:33 pm
content: Actually there is something to the lead resistance even if you can delta their resistance out. If you are measuring current, they can have an effect. If you are measuring higher current then they might heat up and contribute a higher resistance and might heat up more if they have a higher internal resistance. If you are measuring capacitance, then the resistance might also have an effect. Very low voltage measurements might be affected.Of course the above is all close to being negligible in almost any case you might run in to. One thing the internal resistance of the probes might be is a general indicator of the actual quality of the probes. We will see in a little while.

author: ftransform
author_rank: Frequent Contributor
timestamp: June 02, 2013, 06:33:22 pm
content: So I wonder what the heck my probes are made of that they have a 0.01 ohm resistance?How are my Jindo probes better then fluke probes?When I sharpened them on a stone I found that they have a slightly yellow/brassy colored metal, but the surface does not effect the measurement. Silver plated brass?I wish I did not sharpen them but oh well, they still hold a low resistance and its been three years since I sharpened them.And btw, I compared a 4 wire resistance measurement using good probes (30 miliohm each) and shitty probes (1.5-3 ohms each, "copper coated" steel that sticks to magnet for wire) on a 100 ohm resistor, and there was noticeable deviation. IDK what to do with these "copper" probes, serves me right for buying the cheapest crap on ebay. I feel bad trying to fool the scrap yard....I did not figure there would be so much difference in the 4 wire method. I think it was like half an ohm or more... maybe I should redo the experiment.

author: Lightages
author_rank: Unknown
timestamp: June 02, 2013, 06:57:14 pm
content: Quote from: ftransform on June 02, 2013, 06:33:22 pmThey are probably chrome plated,or nickel plated or some other alloy of these things. Some leads will be brass base metal, some steel, some are solid stainless steel.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: June 03, 2013, 02:00:51 am
content: I have to say, the probes that came with my Harbor Freight rebadged Mastech were surprisingly high quality (considering the meter was a ridiculously bad piece of shit). They are almost top-notch: machined needle tip (I literally drew blood), UL rated wire, machined banana plugs, internal resistance of around 0.03 ohms per lead. The only thing is they aren't silicone wire (even though it is UL rated). All of this with a $15 meter.

author: true
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:31:31 am
content: Quote from: PedroDaGr8 on June 03, 2013, 02:00:51 amAre you referring to the Cen-tech P37772 / Mastech M9xxxx whatever? Yeah, the meter is flaky, but I use the probes it came with on one of my Flukes. Are yours bent? I think mine took a set when they were stored behind the Cen-tech. Maybe you can tell me if the plastic is normally bent out of the box.

author: nanofrog
author_rank: Super Contributor
timestamp: June 03, 2013, 02:54:23 am
content: Quote from: ftransform on June 02, 2013, 06:33:22 pmSounds like nickel plated brass, which is found in good quality probes(not used in a heavily corrosive environment). Can't recall chromium plated brass in any data sheets for probes, but it may be floating around.Besides stainless steel, some are gold plated. Probemaster gold plates theirs, and Brymen offers higher quality leads as an option that are gold plated as well (iirc, the rebrander has to order them).

author: PedroDaGr8
author_rank: Super Contributor
timestamp: June 03, 2013, 03:04:47 am
content: Yep, exactly. The meter is literally one of the worst quality wise I have ever seen. At least with the 830-variants, you know you are buying a stripped down meter. They are small and light, you don't expect much. As for this one, I don't think I have ever felt a meter that feels and looks like an old VHS cassette (its enormous and hollow and the plastic is the same black stuff VHS cassettes were made out of).As for the leads, mine are perfectly straight out of the box. I was checking them and just noticed they have a slightly indented section for your fingers.Considering the usual price of leads in stores, the leads and the fact that 20% off coupons are everywhere. You can get the leads for about $15 and trash the meter.

author: robrenz
author_rank: Super Contributor
timestamp: June 03, 2013, 12:00:56 pm
content: Quote from: ftransform on June 02, 2013, 06:33:22 pmMy guess is the Jindo probes are significantly shorter total length than the Fluke probes. Resistance is proportional to length for the same size wire.

author: grenert
author_rank: Frequent Contributor
timestamp: June 03, 2013, 01:20:16 pm
content: Quote from: PedroDaGr8 on June 03, 2013, 03:04:47 amNo need to do this when you can get Pomonas for $15:http://www.mouser.com/ProductDetail/Pomona-Electronics/5519A/?qs=sGAEpiMZZMv8kklI404QlQBG%252bFtG8BXZ(note Mouser lists these as PVC, but I believe they are silicone, and the datasheet also says silicone)Or Probemaster for $15:http://www.probemaster.com/product_info.php?cPath=2_12&products_id=198These are nice in that there are several plug options in case you need something other than the usual right-angle shielded plug.

author: Unknown
author_rank: Unknown
timestamp: June 03, 2013, 02:01:48 pm
content: Quote from: grenert on June 03, 2013, 01:20:16 pmThese look similar to the Fluke TL-71 leads (no surprise, since Pomona manufactures most of the Fluke-branded leads), which are quite nice, especially for this price.Quote from: grenert on June 03, 2013, 01:20:16 pmThe same applies to Pomona. The only issue is that they have completely different model numbers. The catalog (not sure if that's still available) lists them all together. Of course distributors may not stock alternate plugs, and they will probably be more expensive.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: June 03, 2013, 02:21:23 pm
content: Sorry I knew online there were better prices online, I worded that really badly. I meant in B&M stores, so when you are in a pinch and need something TODAY, these are some good alternatives.Quote from: grenert on June 03, 2013, 01:20:16 pm

author: ftransform
author_rank: Frequent Contributor
timestamp: June 04, 2013, 06:50:21 am
content: Quote from: robrenz on June 03, 2013, 12:00:56 pmhow long are your guys fluke probes?

author: ve7xen
author_rank: Super Contributor
timestamp: June 04, 2013, 08:11:53 am
content: Quote from: alm on June 03, 2013, 02:01:48 pmThey're quite good, hard to beat for the money. I made a short video on them, since they aren't often mentioned. They do have silicone leads.Also interesting to note is that Fluke owns Pomona.

author: robrenz
author_rank: Super Contributor
timestamp: June 04, 2013, 12:38:45 pm
content: Quote from: ftransform on June 04, 2013, 06:50:21 am2 of my fluke sets are 55" another is 52.5"My Pomona set with interchangeable plug in ends is 52.5 with the probes plugged in.My Circuit Specialists freebie meter (not a bad meter) leads are 34"

author: saturation
author_rank: Super Contributor
timestamp: June 04, 2013, 01:25:10 pm
content: DMM probes are designed to be used in the field and thus are key features are safety, easy to handle, and durable. Low resistance, how low? DMM probes are not made for precision measurements. Given the diameter of the wire and the length, you'll always get some milliohm resistance, which is negligible for the accuracy of HH DMMs. To remove milliohm contribution is more than just 2 wires in an insulator, it also requires eliminating spurious RF input, thermal noise, contact resistance and a few others, you can't do such measurements in the field and thus, such probes are more delicate and made to be used in the protection of labs and benches.

author: JimmyMz
author_rank: Regular Contributor
timestamp: June 04, 2013, 01:39:56 pm
content: Quote from: robrenz on June 04, 2013, 12:38:45 pmHello Robrenz. You have provided the length of the probes+leads, but how long are the probes?

author: robrenz
author_rank: Super Contributor
timestamp: June 04, 2013, 02:03:37 pm
content: 140mm overall including metal tip, metal tip itself is 18mm