Franky's Kelvin Clip kit. - Page 1
Forum section: electronics / testgear

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 04, 2015, 03:58:50 am
content: As many of you know, Franky on here sells a DIY Kelvin clip kit. After some waffling I decided to try his most recent iteration of this kit and I must say I am thoroughly impressed. He has a winner of a kit for sure.Contents of the kit:4x Banana plugs - 2x red, 2x black.1.2m of red 14AWG silicone wire1.2m of black 14AWG silicone wire2x updated Kelvin clipsRed and Black high quality heat shrinkI opted for the stackable banana plugs, though in hindsight I should have gone with the standard shrouded like he originally offered. The stackable plugs are great for individual cables but make no sense here.The kelvin clips are made by ETA (Electronic Test Accesories) Taiwan and appear to be the same ones used by GWInstek for their LCR leads. These clips feel VERY nice, they are very solid and have a nice spring to hold them together. They grip the DUT nice and tight, without any problem of slipping. The wire connect can easily detach from the body by the removal of a single screw. This makes it VERY easy to solder a very reliable connection without damaging the plastic body of the clip. The quality of the everything feels very good and comes together nice and tight when fully assembled.Cutting the wire to length; each color was cut to two wires of 60cm length. The cable has a nice soft silicone shell and is VERY flexible.Stripping off 5mm of the outer silicone jacket, I was really surprised at the number of strands in this wire. This high number of strands, combined with the soft silicone shell mean this is a very flexible wire which is easy to work with. Another thing to note, unlike most discount Chinese wire there is a solid amount of metal in the wire. I am unsure if the wire is tinned copper, tinned steel or aluminum.EDIT: It is very clearly tinned copper, see the end of the post for the evidence.Stripping 5mm is basically perfect for inserting into the banana plugs.Stripping 2-3mm off of the other end is perfect to fit into the connector to the Kelvin clip. The 14AWG wire is absolutely a perfect fit for these connectors. Sorry for the blurry photo, unfortunately, I didn't realize it was blurry until I started typing.A quick comparison of cheap solder (red) versus Kester 44 (black). Both are supposedly 63/37 solder but it is clear they aren't even close to the same quality. I ended up removing the solder from the cheap one and applying fresh Kester 44.Cutting a bit of heatshrink to cover the connector. This heatshrink really shrinks down, much more than most of the cheap heatshrink I have encountered. Additionally, when it shrinks down it gets a lot more firm, to the point it serves as a kind of strain relief.Trimming the heatshrink back to the camfered edge to allow it to properly fit into kelvin adapter.Putting it all together, large screws attach the connector to the kelvin clip.The screw covers, a very nice touch. There is one for High Force, High Sense, Low Force and Low Sense.Now the most important part, how does it work! Very well, my meter fluctuates between 0.1 and 0.4 mOhm when shorted. Additionally, a precision 294K resistor reads exactly 294.00K. I have NO clue why the images look so compressed, a recent update to my phone really messed up the digital camera it seems.As I said before, I am REALLY damn happy with these. Especially when you consider the price! The whole kit was cheaper than just the clips on ebay. Also, shipping from Hong Kong only took one week, three days of which the package was sitting in New York waiting to be shipped to my region.Edit: I dissolved a small spare portion of the wire in concentrated sulfuric acid so far only the outer tinning has dissolved. It appears to be copper underneath. So the wire is tinned copper.

author: BravoV
author_rank: Super Contributor
timestamp: December 04, 2015, 04:17:07 am
content: PedroDaGr8, thanks for sharing, great post !Quote from: PedroDaGr8 on December 04, 2015, 03:58:50 amAt this stage when using heat shrink tube this, usually I cut and diced a hot melt glue gun stick into small pieces, about rice sized or other suitable sizes, and have them enough stuffed under the heat shrink tube before heating it.Once heated, the glue inside the tube will melt and spread evenly squeezed by the shrinking tube's wall, forming a seamless, strong join from the tube to the thing inside, and sort of laminate it as well.Also the layer of glue once formed and set, will serve as a good strain relief better than the tube alone, particularly near the end of the tube and cable. Sometimes all you need is just to trim the excess glue that oozed out, but its no biggie.

author: BravoV
author_rank: Super Contributor
timestamp: December 04, 2015, 04:47:24 am
content: Quote from: PedroDaGr8 on December 04, 2015, 03:58:50 amI believe the same wires supplied as my purchased of other type of kelvin clips from Franky (Photo) , I believe the wires are tinned copper, photo attached below.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 04, 2015, 04:50:28 am
content: Quote from: BravoV on December 04, 2015, 04:47:24 amYep, I just updated my post to reflect that right as you were posting. I dissolved the tin with sulfuric acid and they appear to be tinned copper. I included an image at the end of the post. Hopefully, by tomorrow I will see the characteristic blue green color of copper sulfate.Sent from my LG-ls990 using Tapatalk

author: edpalmer42
author_rank: Super Contributor
timestamp: December 04, 2015, 05:26:16 am
content: One nice thing about Kelvin connections is that the wires aren't very important. Any voltage drop in the 'force' wires is irrelevant because those wires aren't in the measurement circuit. There isn't any significant voltage drop in the 'sense' wires because the sense inputs are high impedance. As long as the wires are reasonable, both electrically and mechanically, you're good to go.It almost seems a shame to waste nice 14 guage silicone cables on that. They'd make great test leads for current measurements on a DMM.Ed

author: Vgkid
author_rank: Super Contributor
timestamp: December 04, 2015, 05:31:15 am
content: Can you post some pics if the actual clips.

author: Muttley Snickers
author_rank: Unknown
timestamp: December 04, 2015, 05:58:50 am
content: A very nice job and a brilliantly well documented thread....thank you....If you get a chance could you perform a comparison measurement with both 2 and 4 wire using the same setup and equipment, also a link to the product and 99 cent hobbies might be handy for those coming directly from Google.Low ohms and kind regards....

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: December 04, 2015, 06:29:29 am
content: Here are a few pics of the actual Kelvin clips for those interested (click to enlarge):

author: Vgkid
author_rank: Super Contributor
timestamp: December 04, 2015, 06:37:48 am
content: Wow, those do look really nice.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: December 04, 2015, 07:35:37 am
content: Can you provide the link to this kit ?

author: ivaylo
author_rank: Frequent Contributor
timestamp: December 04, 2015, 08:16:49 am
content: Quote from: JacquesBBB on December 04, 2015, 07:35:37 amYeah, I'm not seeing it in Franky's store either...

author: Shock
author_rank: Super Contributor
timestamp: December 04, 2015, 09:40:19 am
content: Quote from: Muttley Snickers on December 04, 2015, 05:58:50 amI only see this test as meaningful if you are making a comparison against another set of leads of an equal length. Assuming the wire is decent quality (again a comparative measurement needs to be made) then the contact resistance of the banana plugs and the clip would seem more important to me.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: December 04, 2015, 10:05:01 am
content: Thanks for all the interest folks. I haven't actually stocked these yet so they are not in my eBay store. I only have one pair left at the moment and someone already PM'ed me so looks like I'm already out. Will try to stock some but problem is I will be going away on a holiday next week until after Xmas, so I'm afraid it will be a while before I can sell these. My apologies for the wait

author: nidlaX
author_rank: Frequent Contributor
timestamp: December 04, 2015, 10:33:56 am
content: Quote from: iloveelectronics on December 04, 2015, 10:05:01 amDoh! I wish you'd stocked these earlier, I would've gotten some with that big order I'd placed. Some of it was actually prepping to build a set of kelvin test leads, but you didn't sell the clips yourself at the time.Nice review Pedro! I've been meaning to post a review of a bunch of odds and ends I purchased from Franky, most of it is quality stuff!

author: Deathwish
author_rank: Unknown
timestamp: December 04, 2015, 10:34:49 am
content: I have enough dmm leads and probes that all i need is the clip on ends to put on those. or its back to using wooden clothes pegs with wires attached

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 04, 2015, 01:56:46 pm
content: Quote from: edpalmer42 on December 04, 2015, 05:26:16 amThe benefit is they fit PERFECTLY into the wire connectors. The silicone shell is a nice solid fit in the outer body of the connector, while the stripped wire is the perfect fit in the inner solder cup portion. While what you say is true, the mechanical benefits of this fit are very evident in how the end product feels. So while there is not an electrical benefitper se, there is VERY much a mechanical and tactile one.Also, I did get another 2 meters of each color, plus the necessary stackable banana plugs, to make some patch cables of my own. I ended up making two pairs of 0.5m and one pair of 1m length cables. They feel perfect and make life much easier when testing multiple meters at once.Quote from: ivaylo on December 04, 2015, 08:16:49 amFranky has often said that he has more stuff available than he lists in his store. Some stuff I guess is stuff he can't get a suitable supply for listing, other stuff is evaluation items, etc. If you are ever looking for something specific it might be worth your time to contact him to see if he has something which will work or can get something easily. Obviously, not everything will sell well and being in business he tends to stock the stuff that will make him the most profit.Quote from: iloveelectronics on December 04, 2015, 10:05:01 amIf I had known this, I would have waited to post my review. Maybe you can setup a pre-order setup, where people purchase and you fulfill when you get back (just being clear that you will be on holiday for the next couple of weeks). I think most of us here known you and trust you well enough for that.Quote from: nidlaX on December 04, 2015, 10:33:56 amThanks Nidla! Yeah, I ordered some extra cable and banana plugs to make my own cables and some of the sprung hook grabbers. Everything is top notch quality, the hooks grip tight and are made of a very nice plastic. They do not feel cheap at all. Light years beyond some of the cheap chinese crap that I have encountered.

author: free_electron
author_rank: Super Contributor
timestamp: December 04, 2015, 05:49:19 pm
content: ooooh . VERY nice indeed ! put on my wishlist ...

author: H.O
author_rank: Frequent Contributor
timestamp: December 04, 2015, 06:10:57 pm
content: Yes, I bought a cheap set on EBAY (ie not from Franky) some time ago and these look much nicer than the ones I got.Hoping for an update to this thread if/when they're available!

author: SeanB
author_rank: Super Contributor
timestamp: December 04, 2015, 06:30:39 pm
content: Nice, and luckily I was able to order something else from Frankie, which was shipped and is already nearly at it's destination. Not for me, but the service from Frankie is always good, too bad he no longer deals with SA because of SAPO and the poor delivery times they have for inbound mail.Suggestion is if Frankie can source some adhesive lined heatshrink in red and black, to supply in these kits, which will make the strain relief much better by supporting the solid soldered wire end. I have used clear ones from RS in the past, and they are very high shrink ratio, and a very good seal especially in wet locations ( I used them in seawater for a long time with no corrosion problem at those joins). The Tyco solderform shrinks are also very good, if not for the cost being so high, even for Aerospace graded parts. Still have a few in a bag for use when needed.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 04, 2015, 09:00:44 pm
content: Quick update: I added some photos of the bare clips themselves to the original post. I thought I had lost these photos when I updated my phone but I found them in a backup. They clearly show the quality of the clips themselves and how they are assembled.

author: vindoline
author_rank: Unknown
timestamp: December 05, 2015, 02:05:09 am
content: for nice use of H2SO4!

author: free_electron
author_rank: Super Contributor
timestamp: December 05, 2015, 03:21:52 am
content: the only thing that worries me a bit is the usage of dissimilar metals between the clip and the wire termination ( where the screw goes in )that may give thermocouple effects..

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 05, 2015, 03:45:59 am
content: Quote from: free_electron on December 05, 2015, 03:21:52 amHonestly, I don't know enough about this but if there are any tests I can do with an HP 34401A and these leads, then let me know.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 05, 2015, 06:33:44 am
content: "Very well, my meter fluctuates between 0.1 and 0.4 mOhm when shorted. "That's impressive. I think mine moves a lot more than that. I tried to make some low resistance measurements with one some time ago without success. It's been a long time but I thought they did not offer a oven as an option and was not chopped?How much does your ambient temperature change?The kit looks nice. Would you gain anything using shielded cable?

author: Shock
author_rank: Super Contributor
timestamp: December 05, 2015, 12:22:07 pm
content: Quote from: joeqsmith on December 05, 2015, 06:33:44 amLess EMF, also depends on how the instrument takes the measurement and averaging.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: December 05, 2015, 05:49:35 pm
content: Thank you, I've found the clips from the kit on eBay and ordered a pair. Not cheap but still a good value for what it is.CheersAlex

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 05, 2015, 06:45:14 pm
content: Quote from: Alex Nikitin on December 05, 2015, 05:49:35 pmHonestly, if you could have waited Franky's price for the whole kit was cheaper than the price of the clips on ebay.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: December 05, 2015, 06:54:18 pm
content: Quote from: PedroDaGr8 on December 05, 2015, 06:45:14 pmProbably not, as the delivery from the US would be almost what I've paid for the clips (with free delivery). Let's just hope that the UK Customs won't charge me extra.CheersAlex

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 05, 2015, 07:09:53 pm
content: Quote from: Alex Nikitin on December 05, 2015, 06:54:18 pmHe ships from HK not USA. But either way, what's done is done. Hope you enjoy the clips, I think they are very well built.Sent from my LG-ls990 using Tapatalk

author: robrenz
author_rank: Super Contributor
timestamp: December 05, 2015, 10:50:20 pm
content: Very nice review and top quality post

author: Alex Nikitin
author_rank: Super Contributor
timestamp: December 06, 2015, 12:07:02 am
content: Quote from: PedroDaGr8 on December 05, 2015, 07:09:53 pmSorry, I did not know his location. Anyway, I hope the clips are good. I have several bits of equipment that can benefit from better Kelvin clips.CheersAlex

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 06, 2015, 01:26:54 am
content: Quote from: robrenz on December 05, 2015, 10:50:20 pmThanks a bunch, it means a lot coming from you. Long time no see by the way, glad to see you back here.Quote from: Alex Nikitin on December 06, 2015, 12:07:02 amIf you got the same model you will like them.Sent from my LG-ls990 using Tapatalk

author: motocoder
author_rank: Unknown
timestamp: December 06, 2015, 03:38:54 pm
content: Very nice. Thanks for the review. I would like to build a set, but would use the really high quality banana plugs that Franky sells, and also maybe the heat shrink that has the glue built in.Franky, please post here when you've got the, back in stock.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: December 08, 2015, 06:48:58 am
content: Thanks everyone who has expressed interest either through postings or PM's. I will have an update on availability and pricing as soon as I come back from my holiday (on the 24th). Hong Kong Post is increasing postage in the new year so pricing will be adjusted accordingly (was $17 for the clips alone, and $23 for the kit, shipped without tracking).

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 02, 2016, 03:57:32 pm
content: A few of the Kelvin clip kit (or clips alone) are now available:https://www.eevblog.com/forum/buysellwanted/franky's-sales-thread/msg833966/#msg833966

author: Vgkid
author_rank: Super Contributor
timestamp: January 02, 2016, 04:23:52 pm
content: Would it be possible for me to browse your ebay store, and make a list of what i want.Then just pay for it here, I do want those kelvin clips.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 02, 2016, 04:27:49 pm
content: Quote from: Vgkid on January 02, 2016, 04:23:52 pmYes. Just PM me a list of items and your paypal email address and I can then send you the Paypal invoice. It's already midnight here so I may not respond until Sunday.

author: Vgkid
author_rank: Super Contributor
timestamp: January 02, 2016, 04:30:09 pm
content: Thanks, will do.

author: BravoV
author_rank: Super Contributor
timestamp: January 15, 2016, 03:43:16 am
content: Quote from: PedroDaGr8 on December 05, 2015, 03:45:59 amVincent, or somebody , please elaborate more details about this so called "Thermocouple Effects" as I'm going to build my kelvin clip for my PM6306 LCR meter.

author: Shock
author_rank: Super Contributor
timestamp: January 15, 2016, 10:29:21 am
content: Quote from: BravoV on January 15, 2016, 03:43:16 amSeebeck, Peltier and Thomson effects.Let us know about what wire and cable design you were planning on using, should start a thread on it.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: January 15, 2016, 12:28:09 pm
content: Quote from: Shock on January 15, 2016, 10:29:21 amI think since this is in this thread, he's implying if using this kit would be acceptable and if not why?

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 15, 2016, 01:25:25 pm
content: Quote from: BravoV on January 15, 2016, 03:43:16 amHi,these thermocouples inside a measurement setup build thermoelectric voltages, which disturb Ohm measurements, 2W or 4W alike, when the resistance is measured with a constant DC current which produces low level voltages over the DUT.This error can be cancelled by the offset compensation method, i.e. the DC current is switched on and off.If you want to do high precision Ohm measurements, i.e. within a few ppm, you need this OCOMP feature, or you need to use better Kelvin clips.AC impedance measurements are usually not affected, so these clips are ok for your PM6306, when you use low frequencies.At high frequencies, the cables will create big errors by parasitic capacitance and polarisation of the silicone.Some nice references (simply search for: Ohm Measurement Offset):Keithley Offset CompensationOCOMP adaptorFrank

author: alank2
author_rank: Super Contributor
timestamp: January 15, 2016, 10:32:19 pm
content: On the straight plugs - how do you get the plug cover over the center? Does it twist in? Pop in with pressure?

author: alank2
author_rank: Super Contributor
timestamp: January 15, 2016, 11:05:26 pm
content: Never mind, I got it. Just takes pressure.

author: seasalt
author_rank: Newbie
timestamp: September 23, 2017, 07:01:27 am
content: Sorry for reviving old topic, just asking is this kit still available for purchase? I have plan to use it with DE-5000.

author: Shock
author_rank: Super Contributor
timestamp: April 04, 2019, 03:14:15 am
content: Quote from: Free_WiFi on April 04, 2019, 01:50:00 amRock solid physically or the best electrical connection? The two parts are secured together quite well with the screw. The problems associated with connecting dissimilar metals was discussed a few posts back.The Gwinstek style is not the ultimate kelvin clip but at $13 for two clips (if you shop around) plus the cost of wire and two banana plugs is quite reasonable.

author: Free_WiFi
author_rank: Regular Contributor
timestamp: April 04, 2019, 04:27:55 am
content: Someone knows the brend of these clips or they are no name ?https://www.aliexpress.com/item/SA-BNC-connector-silver-wire-test-clip-LCR-digital-bridge-LCR-Kelvin-test-clip/1875889865.htmlThanks

author: GreyWoolfe
author_rank: Unknown
timestamp: April 10, 2019, 06:13:58 pm
content: I bought these along with banana plugs from Frankie's store.https://www.ebay.com/itm/2Pcs-Brass-Copper-Gwinstek-LCR-Kelvin-Test-Clip-Microresistivity-Bridge-Champ/322011815415?epid=1084392470&hash=item4af9665df7:g:mfMAAOSwezVWzW7YThey seem to work quite well. That is a 1R1 5% resistor on my GW-Instek 8251A.

author: Free_WiFi
author_rank: Regular Contributor
timestamp: April 10, 2019, 08:18:21 pm
content: Quote from: GreyWoolfe on April 10, 2019, 06:13:58 pmThese clips are not bad,but also not very,very good .... at this point i still prefer these one with thermal isolation,ptfe roller separator and the possibility to solder the wire directly to the alloyhttps://it.aliexpress.com/item/4-Wires-Kelvin-Leads-Test-Clamp-Alligator-Clip-Set-Include-Cable-Safety-Plugs/32577493461.html

author: BravoV
author_rank: Super Contributor
timestamp: April 11, 2019, 07:27:45 am
content: Quote from: Free_WiFi on April 10, 2019, 08:18:21 pmFranky's shop also sell those, I own both types and each has it's own purposes depends on the DUTs.This is bought from Franky while ago.

author: Gary350z
author_rank: Regular Contributor
timestamp: September 18, 2021, 04:58:18 am
content: Bad ETA3105 Kelvin Clips.I bought the ETA3105 Kelvin Clips in 2020, from Franky's, also know as 99centHobbies (ebay seller f-t-2000), and they are crap. The metal didn't look right, so I measured the continuity of the tips of the kelvin clips with an ohm meter (the ohm meter had good gold plated probes) and many times there was no connection at all, even when pressing firmly with the ohm meter probes. Other times the connection was marginal at best, but no where close to zero ohms. They are advertised as gold plated, but I don't think so.These kelvin clips are highly recommended by many people, so I don't know what is going on here. Are these counterfit? I don't know. I have bought other items from this seller and they were good, and this seller is highly recommended on this forum.I eventually bought some BK Precision TLDK1 Kelvin Clip Probes and the make very good connection.

author: J-R
author_rank: Super Contributor
timestamp: September 18, 2021, 07:05:19 am
content: Send him a message through ebay and see what he says. I've always gotten quick responses from him.https://www.ebay.com/itm/173337601080Looking at the photos on the listing it does seem that the plating looks a little off! Maybe some kind of residue that needs to be cleaned or the electroplating didn't go well. Quality control perhaps.Bought a couple sets of Kelvin clips a while back from a different seller:This set had some questionable areas on the plating, dull and some missed spots:https://www.ebay.com/itm/191227969924This set from the same place had mint plating, very shiny:https://www.ebay.com/itm/201604885284

author: mawyatt
author_rank: Super Contributor
timestamp: September 19, 2021, 12:07:04 am
content: Quote from: Gary350z on September 18, 2021, 04:58:18 amThose BK end clips look like the ones supplied with the Tonghui TH26011CS Test Fixture that also comes with their LCR Meters. Makes you wonder if Tonghui is an OEM supplier of some of BK gearThese are definitely a step up (Pro like) from the cheap ones you find on eBay and Alix, we have some of the cheap ones to compare. This isn't to say the cheap ones don't work, they do a good job and can give quite respectable readings compared to the more expensive Pro type if carefully used and calibrated, but likely won't last as long in heavy use.Just as a quick test, we did a side by side comparison of some of the tiny cheap Kelvin probes you find (we had made our own 4 wire probes), not the larger ones that resemble the Tonghui types. Using a piece of 2mm dia Cu wire ~50mm long, with a careful zero measurements and null using a KS34465A, we got results with +-20 micro-ohms of the Tonghui TH2830 LCR meter which was within 20 micro-ohms of what the wire DCR should be. We didn't bring out the other set of custom made Kelvin probes based upon the cheaper clips that look similar to the Tonghui ones, but suspect results would be similar.Best,