Tek Clone Instrance ICP 5025 Current Probe - Page 1
Forum section: electronics / testgear

author: Martin72
author_rank: Super Contributor
timestamp: December 12, 2020, 11:04:03 pm
content: Hi at all,This here:https://www.aliexpress.com/item/32881821930.html?spm=a2g0o.detail.1000060.3.74029dfdjyBtYa&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=7a0ec224-3e00-46c2-a87d-19bab3ef6e6a&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:7a0ec224-3e00-46c2-a87d-19bab3ef6e6a,tpp_buckets:668%230%23131923%230_668%23808%234094%23170_668%23888%233325%2317_668%232846%238110%23382_668%232717%237567%23973_668%231000022185%231000066058%230_668%233468%2315613%23408Makes me curious for weeks...25Mhz, 20A, degaussing function....Only teardrop are the accuracy of 3%, as I know that our old AP011 from lecroy got 1% typical - But costs much more....3% sounds less, but keep in mind when you´re measuring a 10A current flow, it could vary between 9.7 and 10.3A...Nevertheless, very interesting as I don´t know any current probe at this price, which use current compensating measuring method....Hm-hm....Buy it or not...500€ plus taxes...Martin

author: uski
author_rank: Frequent Contributor
timestamp: December 13, 2020, 01:10:10 pm
content: I have no idea if this is good or not, but the price of oscilloscope accessories has always been grossly overpriced. In fact, it looks like the entire industry is overpricing. Look at the software bandwidth limitations... companies are selling you "bandwidth upgrades" for thousands of dollars, for hardware that you already paid.So I would not be surprised that, one day, we see equipment for much closer to the true production cost. Maybe this day has finally come ?

author: jonpaul
author_rank: Super Contributor
timestamp: December 13, 2020, 02:16:37 pm
content: Get the Tektronix current probe catalog, many types and amplifiers depending on max I, freq, jaw size, DC, etc.Used can be found on epay, but beaarw dropped units have cracked ferrite.For any serious use or if safety or compliance is involved I would NEVER buy Chinese junk knockoffs.Stick to TEK (or Yokogawa) probes.Jon

author: H.O
author_rank: Frequent Contributor
timestamp: December 13, 2020, 06:44:22 pm
content: It even has a thumbwheel forbanlanceFor $600 they could at least get the spelling on the sticker right but it seems you have to spring for the 40A version for thatNever the less, it's all about the performance and buying 30 year old Tek probes and amplifiers on EBAY sure is a gamble. Intersting find, would be cool to see a proper review - too much money to buy one just for kicks.

author: Martin72
author_rank: Super Contributor
timestamp: December 13, 2020, 09:07:35 pm
content: Hi,QuoteThis is one of the points - I´m searching several times for AM503B plus A6302 like we got threetimes this combo at work.But it´s hard to get or too expensive and....Space, the amplifier/powersource is a real spacekiller on the bench.Therefore, this thing makes me curious.Other todays probes with degaussing on board/this bandwith costs much much more..But they got much more complex powersource also, instead of an simple AC adpator in case of the instrance...It could be that I´ll think it´s now or never and just order this thing...Must think about for a while.

author: Martin72
author_rank: Super Contributor
timestamp: January 04, 2021, 10:13:07 pm
content: QuoteFinished thinking about.Ordered...

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: January 04, 2021, 10:19:32 pm
content: Quote from: Martin72 on January 04, 2021, 10:13:07 pmMartin, hopefully it's a decent product - I look forward to your evaluation when you receive it. This is one item that my lab currently lacks as well.Good luck!!-Torsten

author: Martin72
author_rank: Super Contributor
timestamp: January 04, 2021, 10:22:58 pm
content: Thankyou Torsten!Will check this in the same manner I´ve tested the Micsig CP2100B probe..Noiselevel, "real" currents (not only some windings through the probe), bandwith/risetime, etc. ...Should arrive in 4 weeks.Martin

author: Kean
author_rank: Unknown
timestamp: January 05, 2021, 01:29:33 am
content: Looking forward to seeing the results. I've been eyeing these for a while, but can't really justify the purchase.

author: Martin72
author_rank: Super Contributor
timestamp: January 05, 2021, 01:35:28 am
content: Me too, to be honest - But there must be someone who try it at first.And in this case it is me...Like Marcellus Wallace in "Pulp Fiction" said, we won´t think, we want to know..

author: achub
author_rank: Newbie
timestamp: January 06, 2021, 08:44:08 pm
content: I've bought one (ICP5050 - 50MHz version) for my students around a year ago for debugging where we do not have enough fancy Tektronix current probes.We are happywith it, considering the cost. It looks like a copy of some older generation probe.We have compared it to a 120Mhz probe from Tektronix (6 times more expensive) by measuring transformer current in a 100kHz dc-dc converter. At that time, waveforms were exactly the same when taken on the same scale. I will ask guys to check this again, one year later.I am considering buying more of these, and more differential MicSig voltage probes for noncritical lab work, prototype debugging. Pictures for reports I prefer to take using the fancy probes from Tektronix as they have lower noises, but not significantly lower.

author: achub
author_rank: Newbie
timestamp: January 07, 2021, 07:55:26 pm
content: The picture shows a comparison of ICP5050 20A/50MHz probe (dark blue) and Tektronix TCP0030A AC/DC Current Probe, 120 MHz/30A

author: Martin72
author_rank: Super Contributor
timestamp: January 07, 2021, 08:24:19 pm
content: Indeed not bad, makes more and more curious...But it will take some time until it´s arriving...

author: Martin72
author_rank: Super Contributor
timestamp: January 20, 2021, 06:11:37 pm
content: Surprise, surprise....Came from work, a package lies on the floor...Ordered on 04.01. arrived NOW, not bad andwithoutany additional taxes....More in the next days....Martin

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2021, 12:17:57 pm
content: Hi,Here some first impressions before testing:Cames in an ordinary package with foam into - No plastic bag like the micsig come with.Nice: European AC adaptor was included.Building quality is good, but can´t compete against the micsig cp2100b ( how the hell they´ve done this at this price), it´s a real lightweight one..In the official pics you can see, that "balance" was written "banlance" - here there is only "balance" - but with a space between ba and lance...And the thumbwheel for balancing the probe should be renamed to "long thumbnailwheel"...Of course, the wheel shouldn´t be that wide out of the housing for unwanting adjustment while handle the probe.But you need longer nails to reach it..OK, acceptable building quality, funny things aka Ba lance and the deep thumbwheel - For a chinese product it´s relatively expensive so let´s hope their focus lies on the inside instead of the outside of the probe.Let´s find it out soon.

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 23, 2021, 12:56:03 pm
content: Interesting. Martin , can you generate 10ns or faster current pulses to test it?

author: Noy
author_rank: Frequent Contributor
timestamp: January 23, 2021, 01:04:08 pm
content: Tear it down!!! We want pictures!! :-)

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2021, 01:48:20 pm
content: Nice but also more than 5 times more expensive:https://eleshop.eu/siglent-cp5030a-current-probe.htmlQuoteHere, I´m afraid not - Only things I´ve got here at home are a 60Mhz generator from siglent, bodnar pulsgen and the siglent deskew fixture.At work we got a philips 50Mhz pulsegenerator, may be I could do some tests with it, when time will allow it.QuoteFirst testing it...Plus I´m afraid of the housing when warming up the shields (where maybe screws are under it), that it melts even by temparatures under 100°C...

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 23, 2021, 02:51:39 pm
content: Quote from: Martin72 on January 23, 2021, 01:48:20 pmIt is the risetime that matters. Maybe with the philips pulse generator set a the 1MHz rate, maximum output voltage and minimum risetime, and loaded with a 50Ohm termination, you can measure its current.

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2021, 03:06:56 pm
content: We got thePM5715, with a variable risetime of 6ns-500ms...

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 23, 2021, 03:19:04 pm
content: Quote from: Martin72 on January 23, 2021, 03:06:56 pmSo it is going to be 10V/100Ohm, a 100mA pulse, 10mV measured at the scope.

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2021, 03:55:17 pm
content: Yepp, will take the probe to work next week, then we´ll see.

author: Martin72
author_rank: Super Contributor
timestamp: January 29, 2021, 09:22:18 pm
content: Hi,As I was very busy on work, at least today I oculd take a noisefloor comparison just like I did with the micsig.Compare the tek a6302, lecroy ap011 with instrance icp5025, scope was a lecroy hdo6034a.50mA/Div. like used on the micsig test was in this case "not enough", so I´ve decreased to 20mA/div and finally to 10mA/Div.Not bad....not bad...

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: January 29, 2021, 09:32:04 pm
content: Martin - thanks for sharing this.It does look promising.In the last image, the 'noise' seems quite regular - is it possible that the probe is picking up a stray field from something nearby?

author: Martin72
author_rank: Super Contributor
timestamp: January 29, 2021, 10:17:59 pm
content: Hi,I won´t deny this as the probes were lying on the table where I got a running testsetup at this moment.Nevertheless, it´s a very positive result - I got scared before what the noiselevel concerns, but it seems, they made their homework(RMS level between 600-960µA).Appx 500€ for this model....Nice but let´s wait for the next tests before getting too euphoric..

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2021, 07:02:04 pm
content: Hi,No further testing yet at work, except one thing...Got a switching circuit for testing here, must test it with the tekA6302 - So I test the circuit with the instrance too.Looks nice...More to come in a couple of days.Martin

author: Martin72
author_rank: Super Contributor
timestamp: February 05, 2021, 05:44:23 pm
content: Further testing will go step by step, depending on having time for it at work.Today risetime and skew, compared to the tek A6302.Generator´s risetime is about 5.4ns, frequency 1Mhz.Again, the results are looking good for the ICP probe...Although I´ll repeat the skew comparings, as I´ve forgot to zeroing both probes and maybe using one ADC (Ch1,Ch2) will take an further effect of the measures.More to come next week, real DC-Load, checking the accuracy, checking the degaussing function.Stay tuned...Martin

author: PartialDischarge
author_rank: Super Contributor
timestamp: February 05, 2021, 06:56:18 pm
content: So the bw is more or less 18-20Mhz. Also the A6302 is not well compensated, horribly I'd say, probably needs adjustment in the AM503 amplifier.

author: Martin72
author_rank: Super Contributor
timestamp: February 05, 2021, 07:09:49 pm
content: Yes, you´re right.After thinking about it, it must be something wrong in my measurement.Instrance should have appx 14ns, Tektronix appx 7ns....Will try to repeat it on monday.

author: PartialDischarge
author_rank: Super Contributor
timestamp: February 05, 2021, 07:15:41 pm
content: Quote from: Martin72 on February 05, 2021, 07:09:49 pmIt doesn't have to be wrong. The compensation problem is common in these types of probes, the A6303 had adjustments in the probe to do this. I've seen Tek probes with AM503 way out of measure, because their adjustment is not easy.The risetime also is something tricky, I don't know in what conditions Tek tests their probes cause I've had problems to get the full risetime in the A6303.

author: Martin72
author_rank: Super Contributor
timestamp: February 05, 2021, 10:24:25 pm
content: Hi,Both probes are under their claimed bandwith, the tek even more than the instrance probe.I´m quit sure that there are no 20Mhz banwith-limiters active, on scope and also on the am503 amplifier unit.But I´ll have a look again.Additional I´ll check the bandwith of the instrance with the bodeplot, when I´ll take it back to home.But first other tests as mentioned before.Actually this probe is just fine in the things I´ve tested so far, it won´t bother me that much, when it doesn´t got the claimed 25Mhz.For appx 500 bucks you never find anything equal or better.

author: Martin72
author_rank: Super Contributor
timestamp: February 06, 2021, 10:28:50 pm
content: After thinking a while about it, I´ll repeat the risetime test completely.Using the philips generator, connect a bnc cable to the scope, setting its input to 50Ohm.The internal 50Ohm will also be the load for the gen and I´ll measure the current through the bnc cable.Setup on last friday wasn´t ideal for measures with a frequency of 1Mhz:Gen---bnc T-adaptor--one bnc cable to scope for voltage measure, one bnc to banana cable to a resistor decade box, setting to 100 ohms.I expect better results when repeating it with the "direct" method.Maybe very soon, on next monday..Martin

author: Martin72
author_rank: Super Contributor
timestamp: February 10, 2021, 08:37:06 pm
content: Hi,No, on wednesday....What I´ve done taking a bnc cable from the philips gen directly to the scope, input setting to 50Ohm as a load.Then hook the probe to the + of the cable.The results were "dramatically" better as before.Risetime of the ICP5025 is now under 10ns ( 14ns in spec), deskew is only 12ns....(Micsig CP2100B above 160ns)Only teardrop, the signal have overshoots due to the impedance mismatch I guess (Input 1Mohm) - But I don´t know how to correct this, switching the scope input to 50Ohm, the overshoots are gone but the signal decrease to very low level.Second pic is the tek a6302 witch appx. 8ns risetime and 22ns deskew (and no overshoots of course).So bandwith of the ICP seems to be prooved/better than the claimed 25Mhz.Martin

author: tautech
author_rank: Super Contributor
timestamp: February 10, 2021, 08:50:38 pm
content: Skew means little in the scheme of things as we can null it out however the lower skew and overshoot might indicate the clone could have used a slower velocity factor cable for lower ringing.Not 100% sure but maybe something worth trying is different coax cabling.

author: Martin72
author_rank: Super Contributor
timestamp: February 10, 2021, 08:54:56 pm
content: QuoteYeah, but some scopes have limited adjustment capabilities, so a low deskew in itself would be welcome.QuoteYou mean the cable from the probe itself ?

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: February 10, 2021, 09:45:27 pm
content: The over/undershoot is fairly large - are there any adjustments on the unit for this?Otherwise the probe performance looks 'nicht schlecht'

author: Martin72
author_rank: Super Contributor
timestamp: February 10, 2021, 10:27:07 pm
content: The probe looks "sehr gut"....The micsig was a class of it´s own regarding it´s price.The Instrance could top it in every way (Noise, Bandwith and soon testing accuracy) plus more handy to use, plus degaussing function.The next probes which are equal to this will cost 3000 or more - fantastic value for the instrance.But the overshoot thing, I must find the problem why it appears now.On the first test it wasn´t there.It seems to be an impedance mismatch problem - Instrance "say", the input must be 1Mohm.Well, if it´s so, measurings beyond a specific frequency will have these overshoots...So why having a probe with wide bandwith when you couldn´t use it at all the bandwith...Maybe there´s another way to compensate these overshoots, I´ll try it out.Only adjustments are the zero compensation via thumbwheel and the ( for this price maximum exclusive) degaussing function.

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: February 10, 2021, 10:41:31 pm
content: I fully agree - the performance we are seeing so far is quite excellent for the price. This is on my shopping list for after the CNY.Interestingly, the output is not ringing...it literally is just overshooting and then settling. Almost like the output buffer doesn't have the correct compensation components installed.You may want to try adding a small capacitor (to GND) to the output just before the scope...or increase the coax length - just to see how it affects the overshoot......thanks again for sharing your findings - I understand this is not Zero effort. Really helps with purchase decisions.

author: Elasia
author_rank: Frequent Contributor
timestamp: February 10, 2021, 10:58:05 pm
content: You see this 50MHz version for 700 bucks? Crazy.. only downside is no usb port or battery... wall wort? ughhttps://www.aliexpress.com/item/32827427938.html?spm=a2g0o.productlist.0.0.497c2284rgxL0X&algo_pvid=ccce1452-4801-45b9-9da5-3f10326aa30b&algo_expid=ccce1452-4801-45b9-9da5-3f10326aa30b-0&btsid=0bb0622c16129976307807398eea60&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

author: Martin72
author_rank: Super Contributor
timestamp: February 10, 2021, 11:17:03 pm
content: It´s the same here but with 50Mhz.This probe here got appx 38Mhz, which were excellent for it´s price too.But I measure a 1Mhz current signal and got overshoots, it won´t be different when you use the next model with claimed 50Mhz.We must eliminate this before we can get upset about this fantastic price vs what you get thing...

author: Martin72
author_rank: Super Contributor
timestamp: February 11, 2021, 10:22:55 pm
content: Quote from: Martin72 on February 10, 2021, 10:27:07 pmI´m dumb....Like a german comedian said, everyone got a moment in a day, where he´s dumb as a worm...This was mine.After thinking about for a while, then reading the short manual of the probe, there are not a statement in it, that you have to use the 1M input of the scope.There´s no statement at all, which input you have to use.But it should be clear, that a signal of 1Mhz won´t be diplayed proper if you use the 1M input.It wasn´t clear to me at this moment I´ve tested it -RF signals are way beyond of the frequencies I´m with it..Tomorrow, at friday afternoon I got the time to test it again - And will do.Martin

author: Martin72
author_rank: Super Contributor
timestamp: February 12, 2021, 09:10:02 pm
content: Hi,Conclusion of today, the Instrance wants to have a 1Mohm input....If the output impedance of the probe were 50ohm, the outputlevel should be halfed when connecting to a 50ohm input.But the outputlevel of the probe drops down to only appx 15% of the former value when connected to 1Mohm input.So you must use the high impedance input - And live with the overshoots...Or not ?Martin

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: February 13, 2021, 12:41:41 am
content: Martin - based on the numbers you have presented, it looks like the output impedance of the probe is around 600ohms.Based on this, try adding a 200pF capacitor to the output. This should attenuate the overshoot....unless my math is badEdit: forgot to mention...the 200pF is a starting point. You'll probably have to reduce the value so you don't completely trash the rise time.

author: Martin72
author_rank: Super Contributor
timestamp: February 13, 2021, 09:02:11 pm
content: Hi,I´ve ordered a BNC-housing from Telegaertner and a trim-capacitor.After building this together, you should be able to trim the signal just like you adjust a probe before using.By the way, it´s NOT written in the "manual", but visible at their webpage, the output is for 1Mohm termination...

author: Martin72
author_rank: Super Contributor
timestamp: February 17, 2021, 09:07:40 pm
content: The stuff has arrived today.Boy, the Telegaertner adaptor building quality is superb...Hopefully, I could assembling it together next friday and repeat the measure on 1Mhz.

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: February 17, 2021, 09:28:09 pm
content: Martin - that's areally nicelooking housing! Would you mind sharing the part number??

author: Martin72
author_rank: Super Contributor
timestamp: February 17, 2021, 09:34:59 pm
content: Of course:https://www.telegaertner.co.uk/media/catalog/product/j/0/j01008a0807.pdfCanada Distributors:https://www.telegaertner.com/en/worldwide/ca/

author: Martin72
author_rank: Super Contributor
timestamp: February 21, 2021, 11:05:32 am
content: Nearly finished, a hole still needs to be drilled ...

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: February 21, 2021, 12:01:46 pm
content: Looks good.Have you done any preliminary tests with the extra capacitor yet?

author: Martin72
author_rank: Super Contributor
timestamp: February 21, 2021, 05:45:27 pm
content: Hi,Not with the probe as it is still at work, but I´m playing a bit around with the bodnar pulse gen, there´s something happening when trimming...Next step is to test it with the probe.If this fails, another cap value will be taken.Martin

author: Martin72
author_rank: Super Contributor
timestamp: February 26, 2021, 10:04:16 pm
content: It´s always friday I can do something with it on work...Today I´ve tested the adaptor, overshoots won´t disappear completely but it´s an advantage.Risetime increases from under 10 to 14ns, no worries for this as it is still in it´s specs for the 25Mhz version.Also I´ve measured again the outputlevel drop, when activating the 50Ohm termination of the scope.It´s nearly exactly 20% from the level when 1Mohm is the terminator.E.g., 10mV outputlevel at 1Mohm, 2mV at 50Ohms.Next friday, I´m planning to make the other "ordinary" tests like current measure up to 20Adc/ac, then doing a summary of all tests so far (pics) and my final verdict.And then.......I´ll look how to teardown this thing.

author: 2N3055
author_rank: Super Contributor
timestamp: February 26, 2021, 10:10:26 pm
content: Quote from: Martin72 on February 26, 2021, 10:04:16 pmThat means internal impedance is about 200 Ohm... Can you try experimenting with termination with 200 on scope input ? Scope on 1Meg, external 200 ohm in parallel with input and then see what step response looks like ..

author: Martin72
author_rank: Super Contributor
timestamp: February 26, 2021, 10:18:29 pm
content: Hi Sinisa,Yep, will do it in the next week.A second telegaertner adaptor housing would be nice for this, as the resistor should be as near as possible to the input from the scope.I think, I´ll modify my actual adaptor for this test.MartinEdit:same pics with 2mV/div resolution, nice low noise..

author: tautech
author_rank: Super Contributor
timestamp: February 26, 2021, 10:55:07 pm
content: MartinHave you used the deskew fixture to check amplitude accuracy ?Sorry if I've missed it in an earlier post.

author: Martin72
author_rank: Super Contributor
timestamp: February 27, 2021, 12:02:29 am
content: Hi Rob,No, the siglent fixture is at home.Martin

author: _Wim_
author_rank: Super Contributor
timestamp: February 27, 2021, 07:58:40 am
content: Quote from: Martin72 on February 26, 2021, 10:18:29 pmA cheaper solution for this is modifying a Chinese Cliquee P57 50 ohm adaptor. I use these all the time for this kind of purposes as they are very cheap and nicely made. They are not ultra sonically welded, but just clicked together, so you can open them relatively easily by prying a screw driver in between, are fully shielded, and contain a small pcb for 3 components to GND and 2 components in series, ideal for many passive small filters!You can by 4 pieces for 20€ including shipping:https://www.aliexpress.com/item/1005001270354160.html?spm=a2g0o.productlist.0.0.30cd6774vb2adH&algo_pvid=17696bb1-0e42-4f31-aaf4-3776e3acd208&algo_expid=17696bb1-0e42-4f31-aaf4-3776e3acd208-0&btsid=0bb0624116144125155554566ec79d&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

author: Martin72
author_rank: Super Contributor
timestamp: March 05, 2021, 09:33:58 pm
content: Couldn´t do something today except determine the output resistance of the probe.It is 230, measured by decreasing an R-decade until the outputlevel of the probe drops down to the half.So next step is to solder a 232R resistor in the adpator and see what happening.

author: Martin72
author_rank: Super Contributor
timestamp: March 05, 2021, 11:12:10 pm
content: Another thing:The noiselevel of the probe should be 1mA rms (spec).1A means 100mV, so 1mA means 100µV..And therefore I didn´t see a difference at the lowest inputlevel of the scope, when the probe was connected or not.1mV/Div., on most scopes the lowest level, means 10mA/Div.A real nice range for such a "cheap" probe, but it could be always getting better:With Tek probe/amplifier you can go down to 1mA - it will always deliver 10mV/div. to the scope...But this will cost you 7 times more (new) than the instrance.I´m really confident so far with this one.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 15, 2021, 04:06:25 pm
content: I'm a uni student diving into design and characterization of SMPS. I have already bought a SDS2074x plus (fully unlocked/hacked by seller), in no small part thanks to Martin72, and DIY'ed a wideband injection transformer that matches or exceeds what Omicron labs offers, I just need a reasonable current probe to fill in the last piece of the puzzle. Having more time to fiddle with tools than money for quality t&m tools meant this device is perfect for my needs. Tests conducted by Martin showed the ICP5025 had the potential of being a "budget" current probe with excellent performance, so I went ahead and bought one for 2757 HKD (~355 USD, >half of my part time job's monthly salary) on taobao. It should arrive in a few days and I'll test and report suggestions proposed by various members on ways to improve the probe's performance. Wish me luck

author: Martin72
author_rank: Super Contributor
timestamp: March 15, 2021, 09:35:56 pm
content: Hi,Whatever you can measure, post the results here, you´re welcome.Me, I got actually not the time I wish I have for further testings..On last saturday, when I was at work, I did some ordinary DC current measures, starting at 10mA, ending with 2.5A (max current of the supply).Nice accuracy, but I will test it until maximum current.And the resistor thing.And the test with the deskew fixture...Hopefully soon.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 18, 2021, 11:33:56 am
content: Received the probe today, don't have much time so I'll just show some waveforms and a bode plot for now.Not sure what is the best way of attaching a current probe to a transmission line without completely screwing it up, but a coax spiced in the middle with shielding jumped with a piece of wire is the best I can come up with for now.The waveforms doesn't seem too distorted but I still have concerns on the setup's effect on the quality of measurement. I am using my hacked SDS2074x plus for the AWG and measurements. Measurements are done with one end of the coax connected to the AWG setup for 50ohm output, probe in the middle, other end into internally 50ohm terminated scope input.The Bode plot confirms the BW of the probe is a touch over 30MHz, which is nice. The frequency response after ~10kHz shows a bit of ripple, I guess that is the frequency where the output starts to be dominated by the current transformer. Would love to attach measurement data in CSV below, but the forum doesn't seem to like CSVs.The AWG square wave rise time is a bit lousy and BW measurement using rise time will require sth a bit better, maybe I should build Jack Ganssle's SquarerUpper when I have some time later. What the square waves did show is the already mentioned overshoot that resembles measurement done with a poorly compensated passive probe.I'll spend more time this weekend to test the suggested ideas, but so far I think this is not a bad product for the money. I do wish they add some fillets to the edges of the probe shell, feels a bit sharp.

author: Martin72
author_rank: Super Contributor
timestamp: March 18, 2021, 08:57:48 pm
content: Nice....But you should disable any bandwithlimiters(per channel, also timebase(when setting it to 10bits, the bandwith will be limited also)), when measuring the risetime.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 19, 2021, 04:29:24 pm
content: I am aware of the BW decrease, but my signal source is not fast enough to measure theactual risetime of the probe as I have mentioned, so that was not supposed to be a proper risetime measurement. In hindsight including the risetime measurement in the screenshot or the screenshot itself was misleading.I went about testing the effects of adding capacitance or a termination resistor to the scope connection. I threw together an adaptor made with a couple of SMA connectors soldered back to back, which is then adapted to BNC. Not the nicest setup but it is what I have on hand. I experimented with a few C0G 0603 caps as well as a 0603 220Ohm resistor. I am quite tired tonight and noticed a few inconsistencies in the scope setup between test runs when reviewing the results, so I'll rerun them properly after I get a bit more sleep.One of the tests that I ran earlier today which I am confident about is the drift test. I left the probe in my bedroom and left home for about 6 hours. The roll mode on the Siglent is 1ksec/div max, so only the last 2.77 hours of data is captured, never thought I'd be complaining about 1ksec/div being too short. Anyways, I had zeroed the probe before leaving home and it pretty much stayed at zero, which is much better than I expected. (In the screenshot, the vertical scale is 5mA/div, which is the highest sensitivity)

author: Martin72
author_rank: Super Contributor
timestamp: March 19, 2021, 09:30:57 pm
content: QuoteSmart thing !

author: Hydron
author_rank: Super Contributor
timestamp: March 19, 2021, 11:35:44 pm
content: The drift test is indeed important. The old Tek AM503s were particularly bad - if you were trying to look at mA level currents they'd need at least half an hour of warmup unless you wanted to keep zeroing them! Then again, they were built with 70s tech, so actually impressive that they basically hold their own still with the modern offerings (once warmed up at least!).Would also be interesting to look at the first half hour of drift if you get a chance.

author: Martin72
author_rank: Super Contributor
timestamp: March 19, 2021, 11:55:49 pm
content: In the "Manual" , Instrance recommends at least 30min (or 20, don´t know it at the moment) for warm up.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 22, 2021, 01:59:40 pm
content: Yep, the first half hour of operation after power on is pretty terrible. I'd say it takes an hour for the probe to fully stabilize.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 22, 2021, 02:11:54 pm
content: Ran a full suite of tests attaching different components in parallel to the output at the scope end.All test is done with full 500M bandwidth, 1kHz square wave generated by SDS2504x plus AWG going into 50 ohm terminated scope input. See my previous post for the construction of the test fixture used to connect the different components to the signal path. Note that the fixture used to connect the resistor and capacitors has a 6.3pF capacitance measured by my DE-5000 LCR meter.Picture 54-56 is the control, just probe output BNC going directly into scope input without test fixture.Picture 69-71 shows result with 220ohm termination. Besides attenuating the signal amplitude, it does not seem to improve the signal quality.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 22, 2021, 02:15:36 pm
content: Picture 57-59 shows result with 6pF 0603 C0G, notice the drastic improvement in the bode plot amplitude ripple.Picture 60-62 shows result with 12pF 0603 C0G.Picture 63-65 shows result with 18pF 0603 C0G.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 22, 2021, 02:25:54 pm
content: Picture 66-68 shows result with 24pF 0603 C0G.That's all the test I ran. The 220ohm termination showed the overshoot at the faster time base is not caused by improper termination, but it really a part of the output.Also I captured the square waves at a slower time base, showing a under compensated response.My theory of the overshoot observed at lower and high frequencies is caused by overshoot in both the lower frequency hall sensor based signal, and in the higher frequency coil based signal.Tbh the overshoot seen in the slower time base bothers me more, as attaching a small cap to the output fixes the higher frequency overshoot and flattens the output response, but it wont help with the lower frequency overshoot.

author: Martin72
author_rank: Super Contributor
timestamp: March 22, 2021, 02:40:38 pm
content: Thank you for your testsSo I must not try it with the resistor anymore....QuoteHm-hm...Now that´s a point, where Instrance could be inform to this and making suggestions of how to fix it.But chances are weak, that we got a contact to them.I wonder what´s inside the probe....but no screws visible.

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 22, 2021, 03:15:15 pm
content: Well I am quite curious about the construction of the probe as well, so I went ahead and tore it down, photos attached.The front sticker peels off easily without residue, revealing 5 PH1 self tapping screws, unscrewing them opens up the unit. Careful not to break the wire connecting the housing shield to the circuit board, the wire has to be disconnected with a soldering iron. The bottom shield is directly soldered to the PCB and has to be disconnected with an iron as well.The soldering looks terrible and is done by hand, I don't see any joints that is on the verge of breaking off, but this thing is not even going to meet IPC class 1 standard I suspect. I can't believe they didn't bother going for proper pick n place and reflow with an item costing this much. Oh and flux is not cleaned off, of course.Looks like they are using isolated dcdc converters to get their split rail. The network of LRC close to the output looks interesting, I wonder if messing with it can unlock more BW, or fix some of the HF overshoot.Not much time at the moment for further reverse engineering, but that is definitely on my to do list.

author: Martin72
author_rank: Super Contributor
timestamp: March 22, 2021, 04:04:08 pm
content: Excellent, hope you can make some hi-res pics from it, sometimes...I wonder for what the blank IC position was good for...But I also see that the voltage will be transformed to +/-15 and +/-5V, really good.QuoteSee some "doublepacked" smd resistors, reminds me of the owon cp05+ probe..

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 23, 2021, 07:16:55 am
content: Here you go:https://drive.google.com/drive/folders/1-NiSVE6oMnOw0oX9vGz-A10eLzvPXPyX?usp=sharingThe photo quality still isn't amazing, but that's all that my phone camera would capture, if clarifications are needed then feel free to ask, I am leaving the probe open for now.The soonest I'll have time to draw the schematics out would be this Sunday.

author: 2N3055
author_rank: Super Contributor
timestamp: March 23, 2021, 07:44:29 am
content: Quote from: Martin72 on March 22, 2021, 04:04:08 pmA 50 Ohm output buffer ?

author: tautech
author_rank: Super Contributor
timestamp: March 23, 2021, 08:01:39 am
content: CP4070A coming soon to have a play with..........Will it be worth the expense ?

author: TopQuark
author_rank: Frequent Contributor
timestamp: March 23, 2021, 12:26:16 pm
content: Funny you bring up Siglent in this thread, I actually spotted the probe under discussion in some of their Chinese marketing materials.Edit: How does one insert an inline expanded photo in the post?

author: Martin72
author_rank: Super Contributor
timestamp: March 23, 2021, 12:39:07 pm
content: Quote from: 2N3055 on March 23, 2021, 07:44:29 amProbably, it´s "Input" is acutally the output of the probe..

author: Martin72
author_rank: Super Contributor
timestamp: March 23, 2021, 04:31:19 pm
content: QuoteCon (vs. ICP5025): Bandwith, no degaussing function, more expensive.Pro: Don´t know..I wonder who are the "real" manufacturer of these probe - You can also get it from Rigol, Testec, Pintek....Rigol RP1001C, 986€Testec TT-CC-220, 554€Pintek PA-622, 387€Siglent CP4070A, 843€Note the huge price-differences....Nevertheless, the ICP5025 cost appx 500€ and I wonder, which benefit these probes could have, to make them partly much more expensive.

author: Hydron
author_rank: Super Contributor
timestamp: March 23, 2021, 05:35:10 pm
content: I think your price list answers who is the real manufacturer(hint - pretty sure it's one of the ones in the list)The other Con you didn't mention is that the CP4070A style probes have significant DC shift with position - they have large gaps in the magnetic circuit (necessary for the SMD hall sensor, the less-precise clamping action and to avoid saturation) that can pick up the earth's magnetic field.The Tek/Hikoi/Instrance probes have thin-film hall elements for the minimum distance between the ferrite pieces that makeup the magnetic circuit, and thus perform much better in this regard (saturation is avoided by the bucking field).Honestly I think the <1.5MHz options similar to the Siglent are a bit redundant now - Micsig is selling options that look cheaper and better than these, while having comparable or better bandwidth and if you need something higher end then sounds like this Instrance unit does the trick for a fraction of the name-brand options.

author: silicon
author_rank: Newbie
timestamp: July 20, 2021, 08:27:47 am
content: I have been following this thread and got in touch with Instrance engineers, who, I must say, have been very willing to help. Like @TopQuark mentioned in one of his posts, I suspected that messing with the LRC network could fix the HF overshoot. The Instrance engineers helped to tune this network and confirmed that the HF overshoot issue was resolved. Each probe is different, so you will have to tune the network yourself. Here are the schematics:Capacitors 4C1 and 4C2 were modified in my case. If I find time, I can make some quick measurements and post them here. But, I think it won't be soon as I'll be very busy with work in the coming months.@Martin72 Thank you for discovering this hidden gem! I don't know if any other probe matches this one in this price range (350ish USD) unless you count build quality and/or are willing to gamble on the used Tek probes.PS: This is my first post. I have been a long time lurker of this forum. I never made an account until this year and always went through the trouble of searching threads by answering the ultimate question of life (42) to the infamous 84/2 question here (which, perhaps, is not famous for members who don't have to answer it).

author: Martin72
author_rank: Super Contributor
timestamp: August 08, 2021, 07:35:03 pm
content: Hi,Finally, i did the deskew measure......appx 55ns delay...not so badWill make the measure again, when I did the "tautech hack" on the deskew fixture (cuttinga part of the pcb out, solder a massive wire between the two edges, more suitable for the jaws of the instrance).Martin