DIY Triaxial Test Leads and Shield Box  (with diode leakage test) - Page 1
Forum section: electronics / projects

author: robrenz
author_rank: Super Contributor
timestamp: January 25, 2014, 03:44:31 am
content: My exploits in making some cables and shield box for my 2450. Also a diode leakage test on the 2450.Thanks Vincent for that cable!

author: Rory
author_rank: Frequent Contributor
timestamp: January 25, 2014, 04:13:46 am
content: Impressive! How can anyone watch your work without pangs of envy over your cool toys?

author: c4757p
author_rank: Super Contributor
timestamp: January 25, 2014, 04:15:58 am
content: Quote from: Rory on January 25, 2014, 04:13:46 amI'm more envious of his skill with them! I'm sure if you turned me loose in his workshop it'd look like kindergarten craft hour

author: Rory
author_rank: Frequent Contributor
timestamp: January 25, 2014, 04:33:42 am
content: Quote from: c4757p on January 25, 2014, 04:15:58 amOne can only admire Robrenz's skill and attention to detail.What I'm wondering is how he can justify the $5k+ cost of that Keithley 2450!

author: BravoV
author_rank: Super Contributor
timestamp: January 25, 2014, 04:36:34 am
content: Quote from: Rory on January 25, 2014, 04:33:42 amHint ... ->Click here

author: Rory
author_rank: Frequent Contributor
timestamp: January 25, 2014, 04:45:47 am
content: That's what I get for being a casual denizen.I guess fortune smiles on those who deserve it. He sure does!

author: PedroDaGr8
author_rank: Super Contributor
timestamp: January 25, 2014, 04:59:30 am
content: Quote from: c4757p on January 25, 2014, 04:15:58 amSame here, I'm envious of his tools but more envious of his abilities. On top of that I love his desire to share with the community. I'm a strong believer in knowledge should be shared when it can.Sent from my EVO using Tapatalk

author: quarks
author_rank: Frequent Contributor
timestamp: January 25, 2014, 10:30:37 am
content: Hello robrenz,that is another great video! Your skills and your attention to details is amazing and just a pleasure to see! Thanks a lot for sharing.Byequarks

author: Bored@Work
author_rank: Super Contributor
timestamp: January 25, 2014, 11:14:48 am
content: Quote from: c4757p on January 25, 2014, 04:15:58 amAnd the problem would be? Because kindergarten craft hour was fun.

author: robrenz
author_rank: Super Contributor
timestamp: January 26, 2014, 03:25:27 pm
content: Thanks everyone for the kind words, glad you enjoyed it.Remember that I am envious of everyone's electronic skills and knowledge.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 26, 2014, 03:54:31 pm
content: Quote from: c4757p on January 25, 2014, 04:15:58 amintel factory does not welcome youlet me tell you one secret... my attention to details is better than himits just i dont have the toolz. now here it goes, its not a secret anymore.

author: Co6aka
author_rank: Unknown
timestamp: January 26, 2014, 06:26:48 pm
content: Quote from: robrenz on January 25, 2014, 03:44:31 amYour "exploits" ("techno-p0rn") are why I'm not getting my work done here...

author: robrenz
author_rank: Super Contributor
timestamp: January 26, 2014, 06:53:08 pm
content: I am glad to help out

author: robrenz
author_rank: Super Contributor
timestamp: January 29, 2014, 01:17:59 pm
content: A fellow forum member is sending me some triax cables made with belden 9222 cable which is not considered a low triboelectric noise cable. When I get it I will post some testing of these versus the HP low noise cables to see if the 2450 can capture any difference.If anyone has experience with testing procedures for triboelectric noise please chime in.

author: Vgkid
author_rank: Super Contributor
timestamp: January 31, 2014, 05:04:04 am
content: Thanks for the video, I found it rather educational.

author: robrenz
author_rank: Super Contributor
timestamp: February 03, 2014, 02:59:55 pm
content: @ Vgkid your welcome.An anonymous fellow forum member offered to make some triaxial cables from belden 9222 and supply some triax bulkhead fittings. I volunteered some machine work in exchange. The package arrived this weekend and Holy Cow this is an arsenal of cables, fittings and adapters for triax/coax. And that metal enclosure with the emi braid gasket is going to make an awesome test fixture.The Belden 9222 is not "low triboelectric noise cable" so I will do a follow up video with the new test fixture and find out if I can see a difference between the Belden 9222 and the Agilent low noise cables using the Keithley 2450.Edit: I forgot to attach the pictureEdit2: I forgot that I said most of this a few posts ago

author: Fsck
author_rank: Super Contributor
timestamp: March 01, 2014, 11:29:50 am
content: if you have a spare 2-lug triaxial male to 3-lug TRB female, I'll buy it off youthat's a kickass set of connectors.

author: ahakman
author_rank: Regular Contributor
timestamp: March 07, 2014, 12:27:52 pm
content: Cool video! Also really cool that you got that keithley SMU for doing a review! That's amazing!As for low triboelectric measurements, the key is to not move ANYTHING for some minutes after getting everything setup, but before you run the test to let any triboelectric induced charges dissipate. I think I remember reading something like 20 minutes suggested settling time in some Keithly low current measurement guide. I regularly use a Keithly 4200 SCS (semiconductor characterization system) with 4 SMUs in it, and even with fancy (expensive) Keithly mini triax cables, if you even so much as bump the desk while a sweep is running, you'll see a spike in the current in thr fA or pA ranges. Not sure I can give you very useful advice though - a Keithly sales rep saw my test setup, and knew what I was trying to measure, and literally laughed at how awful / primative it was (it's been improved somewhat since).And yes, light affects pretty much all semiconductor junctions, so everything must be measured in as dark conditions as physically possible, unless of course you happen to be building a "photon counting" light detector, in which case bring on the home-brew "calibrated" light source! Also, probably a good idea you built your own shielded dark box - sometimes when you buy a commercial $8k "shielded light proof probe station dark box", which albeit is a LOT larger, and has fancy triax feedthroughs and stuff in it, actually comes with a hole in the door big enough to stick your fingers through. The manufacturer says, "ooh, yeah, that model is more for emc shielding than absolute light tightness - the next model up should be better", after waiting a year to get this one! If at some point you need a truly light proof probe station enclosure, I can certainly tell you which one NOT to get! </annoyed grad student rant>I'm really curious if you have any interesting applications in mind for this thing after you do your review. For a grad student, I have some pretty nice test equipment at home, but I can't really think of much one would actually need such a sensitive SMU for in a non-research setting, unless like Jerri Ellsworth, you're fabing your own transistors in the basement, or you have unlimited money for a Cadence license and a connection with someone at a fab that can get your 'fun' projects onto test wafers or something! Doing IV curves of random discrete devices might not be the most exciting thing ever. If that model supports it, be sure to do "dual sweeps", and see if you can find any hysteresis effects when sweeping the bias voltage down vs up!I saw in the other thread where you were looking for the triax cables that you're in Canada too ehWe actually have some of those same HP triax cables in the lab from our old HP semiconductor parameter analyzer, but I didn't think stealing them was a good idea, and triax cables are quite difficult to track down, and sometimes I need a random one, or one cut in half to rig something up quickly myself! Cool to see they can be found on ebay, but I bet they were still expensive! Oh, and not to bee too annoying, but "peak-oh" not "pi-co"

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 07, 2014, 04:59:07 pm
content: Quote from: Mechatrommer on January 26, 2014, 03:54:31 pmMy dad always said: A bad workman blames his tools.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 07, 2014, 05:06:29 pm
content: I use the same 'radio shack' clips in my lab. The v-grove idea is brilliant!Does the shield box have a thin/transparent plastic coating on the inside?

author: robrenz
author_rank: Super Contributor
timestamp: March 07, 2014, 05:13:24 pm
content: Quote from: CaptnYellowShirt on March 07, 2014, 05:06:29 pmThanks, they hold really well with the groove. I lined the box with Teflon sheet held in place with PSA. I think I mentioned it in the video.

author: robrenz
author_rank: Super Contributor
timestamp: March 07, 2014, 05:19:03 pm
content: Quote from: ahakman on March 07, 2014, 12:27:52 pmGlad you liked the video. This is a very handy piece of equipment for general lab use. It is a graphing voltmeter, ammeter, ohmmeter, watt meter. It is a programmable power supply and eload. It is a super low burden voltage ammeter. You don't have to be doing super low end stuff for this to be usefull.I am in the US not Canada.I will work on the "peeeko"

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 07, 2014, 05:43:56 pm
content: Quote from: robrenz on March 07, 2014, 05:13:24 pmOh not like that. I'm was wondering about the lid closing effect.A lot of those metal tin boxes have a plastic film around them to keep them looking pretty -- like what you find on the inside of a soda can so the soda doesn't taste like aluminum.Oh and as far as the word "pico" goes... these EE's don't understand how lucky they are to be able to measure anything smaller than 0.0001 without a $1/2M machine.

author: robrenz
author_rank: Super Contributor
timestamp: March 07, 2014, 06:04:47 pm
content: Quote from: CaptnYellowShirt on March 07, 2014, 05:43:56 pmThat container has no coating at all it is just plated. It give instant continuity with no pressure on the probes.I have things to measure .000001" and .0000001" deviations in the mechanical realm but only +/-.000002" traceable accuracy.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 07, 2014, 06:19:50 pm
content: Quote from: robrenz on March 07, 2014, 06:04:47 pmSweet zombie jesus!Lasers?

author: robrenz
author_rank: Super Contributor
timestamp: March 07, 2014, 07:05:06 pm
content: No, just good old fashioned lvdt based electronic indicators and high end gage blocks.

author: plesa
author_rank: Frequent Contributor
timestamp: March 07, 2014, 09:57:29 pm
content: Quote from: robrenz on January 29, 2014, 01:17:59 pmI have similar test setup with 2636 for testing MPPC, PMT and photodiodes. The triboelectric noise cannot be easily measured, because it is only one of the noise contributor.There are triboelectric and piezoelectric effects. Some controlled bend can be suitable, I think.If the test setup and cables are fixed it was not issue, in 100 fA region. Belden 9222 yellow cable was comparable to Keithley low noise. Only the soldering was too difficult compared to Keithley low noise cable.Everything including conectors I cleaned in IPA the cable ends as well. Stay away from normal heatshrink tube, rather use the PTFE ones.What is the black plastic for the connector front end?I do not have the Agilent or HP triax cables available to compare them.

author: uwezi
author_rank: Unknown
timestamp: March 07, 2014, 10:12:01 pm
content: Quote from: robrenz on January 25, 2014, 03:44:31 amI really like your mod to the aligators/crocodiles!

author: ahakman
author_rank: Regular Contributor
timestamp: March 07, 2014, 11:21:26 pm
content: QuoteOh, I guess that's someone else that's also looking for Triax cables that's in Canada in the buy/sell section. I was rather tired last night and not paying too much attention, and figured it was you.Yeah, perhaps that SMU is actually a lot more flexible than the ones in the 4200 SCS unit, at least when using the supplied software (which feels like a windows 3.1 program that's been shoehorned into running in XP on the 4200). I have a feeling that if you wrote your own software to control the SMUs directly in the 4200, it would also be a much more useful piece of equipment. I always felt that the software on the 4200 is extremely limiting and not at all worthy of controlling the hardware that it is, but I guess it works for the one application it's designed for, and worked for me for what I really needed it to do.The UI on that SMU sure looks a lot better than most Keithly equipment I've used. I've always found Keithly tools try to cram too many functions onto too few buttons, and use too small or limited a screen, and they become unintuitive and frustrating to use. Looks like they solved that problem with a nice graphical LCD and touchscreen interface now!Looking forward to more videos!

author: ahakman
author_rank: Regular Contributor
timestamp: March 07, 2014, 11:27:19 pm
content: QuoteHmmm, this sounds rather familiar. What application are you working on? Wouldn't happen to be bio-related would it? My application is designing and implementing a custom silicon Geiger mode APD that's integrated with regular CMOS (well, HV CMOS) for a sensor in a bio application.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 08, 2014, 12:03:10 am
content: Quote from: uwezi on March 07, 2014, 10:12:01 pmI heard those are called "duck clips" because they look more like a duck bill than crocodile teeth. Not sure what you would call the modified clip, though. Maybe rattlesnake clips?

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 08, 2014, 06:00:35 am
content: Quote from: NiHaoMike on March 08, 2014, 12:03:10 amHow about Trogdor Clips?

author: robrenz
author_rank: Super Contributor
timestamp: March 08, 2014, 01:50:56 pm
content: Which is it Trogdor or Torgdor?You illustration will work for "Jaws of Death" also

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: March 08, 2014, 03:26:18 pm
content: Quote from: robrenz on March 08, 2014, 01:50:56 pmIt's totally Trogdor.See, this is the issue I face day-to-day. Why did the fuse blow? Oh its because you got the test points backwards. Opps.

author: ivaylo
author_rank: Frequent Contributor
timestamp: July 07, 2014, 06:45:08 am
content: Sorry for resurrecting an old thread. Here is my rendering of triax leads and shield box(es) for a Keithley 2636A which I got with no cables to speak of. In the process of trying to find the "cheapest" (turns out nothing triax is cheap!) components I ended up building two sets of shield boxes with cables. In retrospect if I knew how to source all parts from the beginning I would have built the round box only (following the example by robrenz pretty much one to one) but I found enough cable with the same thickness only at the end. I am happy with the result but wouldn't call it a fun project (dragged way too long and costed me much more than I was prepared for). Anyways, gotta finish what you start, hope gives me decent use of the SMU. Thanks robrenz, for the detailed example!

author: robrenz
author_rank: Super Contributor
timestamp: July 07, 2014, 11:09:11 am
content: Awesome jobGlad there was something helpful in this thread.