Franky's Kelvin Clip kit.

[PedroDaGr8]

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 wire
• 1.2m of black 14AWG silicone wire
• 2x updated Kelvin clips
• Red and Black high quality heat shrink

I 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.

[BravoV]

PedroDaGr8, thanks for sharing, great post ! 

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.

At 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.

[BravoV]

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.

I 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.

[PedroDaGr8]

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.

I 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.

Yep, 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

[edpalmer42]

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

[Vgkid]

Can you post some pics if the actual clips.

[Muttley Snickers]

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....

[iloveelectronics]

Here are a few pics of the actual Kelvin clips for those interested (click to enlarge):

[Vgkid]

Wow, those do look really nice.

[JacquesBBB]

Can you provide the link to this kit ?

[ivaylo]

Can you provide the link to this kit ?

Yeah, I'm not seeing it in Franky's store either...

[Shock]

If you get a chance could you perform a comparison measurement with both 2 and 4 wire using the same setup and equipment.

I 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.

[iloveelectronics]

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

[nidlaX]

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

Doh! 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!

[Deathwish]

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

[PedroDaGr8]

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

The 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 benefit per 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.

Can you provide the link to this kit ?

Yeah, I'm not seeing it in Franky's store either...

Franky 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.

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

If 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.

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

Doh! 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!

Thanks 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.

[free_electron]

ooooh . VERY nice indeed !  put on my wishlist ...

[H.O]

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!

[SeanB]

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.

[PedroDaGr8]

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.

[vindoline]

  for nice use of H2SO4!

[free_electron]

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..

[PedroDaGr8]

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..

Honestly, 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.

[joeqsmith]

"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? 

[Shock]

The kit looks nice.   Would you gain anything using shielded cable?

Less EMF, also depends on how the instrument takes the measurement and averaging.

[Alex Nikitin]

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.

Cheers

Alex

[PedroDaGr8]

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.

Cheers

Alex

Honestly, if you could have waited Franky's price for the whole kit was cheaper than the price of the clips on ebay.

[Alex Nikitin]

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.

Cheers

Alex

Honestly, if you could have waited Franky's price for the whole kit was cheaper than the price of the clips on ebay.

Probably 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.

Cheers

Alex

[PedroDaGr8]

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.

Cheers

Alex

Honestly, if you could have waited Franky's price for the whole kit was cheaper than the price of the clips on ebay.

Probably 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.

Cheers

Alex

He 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

[robrenz]

Very nice review and top quality post 

[Alex Nikitin]

[He 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.

Sorry, 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.

Cheers

Alex

[PedroDaGr8]

Very nice review and top quality post 

Thanks a bunch, it means a lot coming from you. Long time no see by the way, glad to see you back here.

[He 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.

Sorry, 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.

Cheers

Alex

If you got the same model you will like them.

Sent from my LG-ls990 using Tapatalk

[motocoder]

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.

[iloveelectronics]

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).

[iloveelectronics]

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

[Vgkid]

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.

[iloveelectronics]

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.

Yes. 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.

[Vgkid]

Thanks, will do.

[BravoV]

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..

Honestly, 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.

Vincent, 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.

[Shock]

Vincent, 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.

Seebeck, Peltier and Thomson effects.
Let us know about what wire and cable design you were planning on using, should start a thread on it.

[PedroDaGr8]

Vincent, 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.

Seebeck, Peltier and Thomson effects.
Let us know about what wire and cable design you were planning on using, should start a thread on it.

I think since this is in this thread, he's implying if using this kit would be acceptable and if not why?

[Dr. Frank]

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..

Honestly, 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.

Vincent, 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.

Hi,
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 Compensation
OCOMP adaptor

Frank

[alank2]

On the straight plugs - how do you get the plug cover over the center?  Does it twist in?  Pop in with pressure?

[alank2]

Never mind, I got it.  Just takes pressure.

[seasalt]

Sorry for reviving old topic, just asking is this kit still available for purchase? I have plan to use it with DE-5000.

[Shock]

Please people,forgive me for my laziness,but i have this question regarding these kelvin clips.
According to this picture you need to use the screw to install the nickel plated part for the wire...
is this a really good way to make an absolutely solid rock contact with the golden plated part ?
I'm asking,because for me these clips didn't looks like an ultimate deal .

Rock 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.

[Free_WiFi]

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.html
Thanks

[GreyWoolfe]

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:mfMAAOSwezVWzW7Y

They seem to work quite well.  That is a 1R1 5% resistor on my GW-Instek 8251A.

[Free_WiFi]

I bought these along with banana plugs from Frankie's store.


They seem to work quite well.  That is a 1R1 5% resistor on my GW-Instek 8251A.

These 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 alloy




https://it.aliexpress.com/item/4-Wires-Kelvin-Leads-Test-Clamp-Alligator-Clip-Set-Include-Cable-Safety-Plugs/32577493461.html

[BravoV]

These 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 alloy

Franky'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.

[Gary350z]

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.

[J-R]

Send him a message through ebay and see what he says.  I've always gotten quick responses from him.
https://www.ebay.com/itm/173337601080
Looking 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/191227969924
This set from the same place had mint plating, very shiny: https://www.ebay.com/itm/201604885284

[mawyatt]

I eventually bought some BK Precision TLDK1 Kelvin Clip Probes and the make very good connection.

Those 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 gear

These 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,