Owon CP-05+ Current Probe (Former Pintek PA622 Thread) - Page 1
Forum section: electronics / testgear

author: Martin72
author_rank: Super Contributor
timestamp: December 27, 2018, 05:09:56 pm
content: Hi everyone,A current probe for my scope would be nice to have but the prices (even used) are high.So I´ve looked around and found this one:https://www.ebay.de/itm/Pintek-Professional-Current-probes-up-to-100Khz-10mV-A-100mV-A-Range-3-5n-R/380412102263?hash=item5892540677:g:gwEAAOSwr81USGj3:rk:3:pf:0Does anybody have experiences with this probe ?It´s a noisy crap thing or is it just worth the price, also the specified accuracy worrying me ( up to 15% by greater current values).Also alternative recommendations are welcome.Martin

author: HighVoltage
author_rank: Super Contributor
timestamp: December 27, 2018, 05:24:48 pm
content: I do not have the Pintek PA622But, for that price you can get a real branded FLUKE 80i-110s AC/DC Current Probe or the same re-branded as Tektronix, Agilent and so on.I have several of these and they are really great and go on ebay in good condition for 200 to 300 Euros

author: Martin72
author_rank: Super Contributor
timestamp: December 27, 2018, 09:52:15 pm
content: Thanks for that !But reading the specs, it got the same deviation up to 15% at higher current rates(from appx 40A on).Maybe it couldn´t get any better in this price range.I will have a look for it, I didn´t often measure on circuits which keeps more than 10, 20 A flowing.Martin

author: natman69
author_rank: Regular Contributor
timestamp: December 28, 2018, 10:21:33 am
content: I'm also interested in this probe. Unfortunately I haven't found a technical review or a teardown. There is only a picture of inside.Some trusted members of the forum recommend the CP-05A current probe (about 110 USD) but also in this case there isn't a technical review.Hope someone will do a review of these probes soon...In a different class of performance there is the Hantek CC-65 (about 65 USD). There are several threads on eevblog about this probe and a deep review with noise measurement and teardown.

author: Martin72
author_rank: Super Contributor
timestamp: December 28, 2018, 05:57:37 pm
content: Thanks for that !Additionally, I´ve found this one in eBayOwon CP-05+(PDF)The price is in the middle of the before mentioned probes..the quality too….? Makes me curious.

author: natman69
author_rank: Regular Contributor
timestamp: December 30, 2018, 08:07:05 am
content: In the same ballpark I've found Picotech current probes:https://www.picotech.com/accessories/current-probes-clampsThe Picotech TA018 is very similar to the Hantek CC-65.Instead CP-05 is available also as CP-05A, CP-05B and CP-05+ but I'm not sure about the performance differences.

author: Martin72
author_rank: Super Contributor
timestamp: December 30, 2018, 10:45:37 pm
content: Thanks for this, meanwhile I think I order the cp05 for testing.Take it to work to compare it with probes from fluke, tektronix and lecroy ap011....

author: Martin72
author_rank: Super Contributor
timestamp: January 03, 2019, 10:15:58 pm
content: Today I test the fluke i 310s probe....not the cheapest one..Boy, what a noisefloor…..You see nothing as long as you not use enhanced resolution or ( in case of the new rigol 5074) averaging…And this one costs 3 times more than a Owon CP05....

author: noidea
author_rank: Unknown
timestamp: January 04, 2019, 05:13:55 am
content: On the subject of cost effective current probes has anyone seen the "A622" AC/DC current probes on the bay of evil, and has anyone bought one? I wonder if they are the same quality as the originalsA622 is the model number of the Tektronix AC/DC probe that a lot of test equipment manufacturers rebadge and sell as their own (Fluke 80i-110S, Keysight 1146a/b etc etc) which to my knowledge were originally made by Chauvin Arnoux as the E3N

author: Vtech
author_rank: Regular Contributor
timestamp: January 04, 2019, 11:48:50 am
content: I have Pintek PA-699 and I'm quite happy with it. It's higher bandwidth version - 1.5MHz.

author: noidea
author_rank: Unknown
timestamp: January 16, 2019, 10:19:39 am
content: Quote from: Martin72 on December 30, 2018, 10:45:37 pmHi Martin72Did you end up ordering a CP05?

author: Martin72
author_rank: Super Contributor
timestamp: January 16, 2019, 07:12:30 pm
content: Hi,Should arrive in this week….Martin

author: dmm2018
author_rank: Contributor
timestamp: January 17, 2019, 03:42:43 pm
content: Bought a Fluke i30s before and it's pulse current response was quite poor (the frequency of signal shown in figure below is 700Hz). Returned to Fluke but the problem could not be solved, then refunded. Bought Keysight 1146B and it's pulse current response is much better.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 17, 2019, 07:02:20 pm
content: Quote from: dmm2018 on January 17, 2019, 03:42:43 pmForget the 700Hz, I wonder what the edge rates were. Looks like it was picking up some noise.These are my DC current probes shown roughly a 200us pulse. I think the LEM's 3dB point is 150K. The old 1960's Tek probe was originally 50M. I ended up getting close to 100K with the cheap UNI-T.1) gate pulse, TTL2) modified UNI-T UT210E3) LEM LA 55-P4) modified Tektronix P6042

author: Hydron
author_rank: Super Contributor
timestamp: January 17, 2019, 08:05:05 pm
content: As it may be of interest, I've attached a pdf summary of some tests I did on a PA-699 Pintek probe (the 1.5MHz 40A one) earlier year. These were quick and dirty checks, and the noise numbers in particular should be taken with a grain of salt, as I have some other screenshots which suggest pk-pk noise about twice as high as I've stated in the PDF. Unfortunately I don't have the original noise capture or the probe available for a re-test, but what is there might still be useful.You're never going to get as good a result with one of these clamp-meter style probes as you will with a real Tek/Hikoi (who make them for everyone else) high frequency probe using a thin-film hall sensor and a DC-nulling design. However those are well into the thousands new (many hundreds for good tested used examples) so the Pintek style mid-range probes may be a good compromise choice for some.

author: Martin72
author_rank: Super Contributor
timestamp: January 17, 2019, 09:45:12 pm
content: Tomorrow the owon will be arrived.I´ll test it on monday at work, together with the fluke i310s and as a reference, the lecroy AP011 probe.This probe got 120khz bandwith and a maxium of 150A peak.Yearly calibrated, matches only with lecroy scopes and you can do auto-zero compensation and....degaussingWhat I can test at work:DC current, AC current 50-400hz, current of an pwm-signal with 10khz up to 100A and more (depending from the testobject I could get)Martin

author: Martin72
author_rank: Super Contributor
timestamp: January 18, 2019, 08:08:45 pm
content: Arrived:Short test without load, really less noise than the fluke i310s, on all ranges…You have to press the auto-zero knob as long as it reaches the zeroposition on scope - it works.Maybe I can do some DC tests this weekend at home.Edit:Specs….

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2019, 11:48:30 pm
content: I took it to work, unfortunately I couldn´t do some serious measurements yet.Except some dc measure on the desktop, they´re looking good.On the following week I could do further tests and report it here.

author: Martin72
author_rank: Super Contributor
timestamp: January 30, 2019, 06:22:48 pm
content: Still waiting for a chance to measure…..Meanwhile I checked the lower dc-current range, setting the cp05 to 4A range."Reference" was a Fluke 89IV and on Ch1 the lecroy ap011.Current control mode by shortening the psu output.Readout from the fluke : 100mA, 251mA, 500mA, 1.03 A dc current:From 1Adc on the results from the cp05 are usable - not too bad for a currentclamp up to 400Adc.

author: Martin72
author_rank: Super Contributor
timestamp: February 01, 2019, 06:00:25 pm
content: AC-current measures today, in the 4A range - Under 1A it´s not usable.Measurings taken with appx 3.9A and various frequencies."Reference" was Fluke 187.60Hz 400Hz 1khz 4khz 10khz 20khzFluke 3.86 3.87 3.84 3.75 3.54 3.14LeCroy 3.84 3.82 3.79 3.67 3.35 2.77CP05+ 3.89 3.90 3.81 3.81 3.64 3.21So far so good…But:I´m sure I did a zero-offset before, both lines ( AP011 and CP05) were on zero-scaling before starting to measure.Now I watch the screenshots at home…(Ch1 Ap011, Ch 2 CP05+, for better viewing not in the same current flow direction)Seems like a positive offset, althoug I did the zeroing before measure.And:The phase deviation between the two channels by increasing the frequency.

author: Martin72
author_rank: Super Contributor
timestamp: February 06, 2019, 06:59:45 pm
content: Teardown:Not much inside for the money.Two pots on the back, Maybe I can adjust the positive offset with them.Trying to make a schematic from it...

author: Martin72
author_rank: Super Contributor
timestamp: February 11, 2019, 10:16:43 pm
content: QuoteStill doing so further tests will come later.The battery voltage is converted to +/- 3V - Too less for some of the used op-amps there.A colleague and me think about modifications to make this probe useful for currents under 1A.If the schematic is complete, it will be posted here.MartinP.S.:The thread title schould be changed, but how…..

author: Martin72
author_rank: Super Contributor
timestamp: February 18, 2019, 10:10:38 pm
content: Schematic so far, Lo Bat detection and +/-3V are missing.Got a look into our Fluke i310S, much more "complicated" Building....this one is very simple.All op-amps need a minimum supply of about +/- 5V.Used op-amps there : OP07C, MC33078, TL062, TL064.Martin

author: Martin72
author_rank: Super Contributor
timestamp: February 19, 2019, 02:05:22 pm
content: "Final" schematic:(no guarantee)MartinEdit : The "zero switch" doesn´t switch "hard", it´s a rubber carbon one with a resistance of appx 80.

author: Martin72
author_rank: Super Contributor
timestamp: February 23, 2019, 09:53:38 pm
content: "Final final" schematic, changed diode D1 into zener type:Next steps : Further measurings, after this increasing the internal supply-voltage from +/- 3V to appx 10V to see what happen, reminding the 3 Volts are for EVERY op-amp in the circuit too less.

author: Martin72
author_rank: Super Contributor
timestamp: February 25, 2019, 06:16:54 pm
content: Today measuring a 300µs pulse, reference was a tektronix probe.300mA:2 A, tektronix :Owon :Noisy and overshoots….

author: Martin72
author_rank: Super Contributor
timestamp: March 30, 2019, 06:18:43 pm
content: Further tests will come….at last.Because:Now I got two…..I´m joking, my clamp was damaged and I asked them for repair.They won´t repair it, they also don´t want the defective clamp back, today I got a new one from them...So now I can do a full "teardown", first I took the cover from the jaw away:Ah, only hall-sensors, no compensation coil….I will clean up the pcb from any parts so I could have a better look to the layout, for completing the schematic.Next week I take some measures on a "real DUT" with the new one.

author: Martin72
author_rank: Super Contributor
timestamp: March 31, 2019, 07:09:08 pm
content: A Picture of the hall sensor, taken with the andonstar microscope:Any idea which could be the brand/manufactor ?Search with "4pins hall sensor smd" wasn´t succesful.

author: analogRF
author_rank: Super Contributor
timestamp: August 19, 2019, 04:13:21 am
content: Martin,did you increase the supplies to +/-5 to see what happens to measurements?or any other tests?

author: Hydron
author_rank: Super Contributor
timestamp: August 19, 2019, 12:11:15 pm
content: Quote from: Martin72 on March 31, 2019, 07:09:08 pmIt may be from Asahi Kasei, they make 4-pin hall elements for this sort of thing:https://www.akm.com/akm/en/product/detail/0004/

author: Martin72
author_rank: Super Contributor
timestamp: August 19, 2019, 06:33:58 pm
content: Hi,QuoteYes, and a little bit higher - Result was the damaged clamp…Still I want to make further tests on work, the clamp is also there but time....

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 19, 2019, 08:17:18 pm
content: Very interesting tear down, please continue.

author: analogRF
author_rank: Super Contributor
timestamp: August 19, 2019, 08:22:20 pm
content: Quote from: Martin72 on August 19, 2019, 06:33:58 pmdo you mean the hall sensor died? because the opamps shouldnt die with +/-5V or even higherbut the current passing through the hall sensor must be limited, so maybe when you increased the supplies the current through the sensor exceeded the limitwas there any change in noise level of the clamp?

author: Martin72
author_rank: Super Contributor
timestamp: August 19, 2019, 08:43:33 pm
content: Hi,Yes, the hall-sensor diedIncreasing the voltage in a region, where every op-amp would function proper was the intention.And the hope, that the noise level would decrease, but it didn´t.They claimed a bandwith of appx 200khz, which wasn´t so bad at all, but I can´t believe it, although the clamp did measure up to 10khz proper, as I test it a few month ago.QuoteI´ll desolder all the parts from the pcb of the defective one, to have a look at all connections( for finishing the schematic).

author: Spacemarine
author_rank: Newbie
timestamp: September 23, 2019, 01:42:14 pm
content: Quote from: Martin72 on August 19, 2019, 08:43:33 pmAny progress on that?

author: Martin72
author_rank: Super Contributor
timestamp: July 09, 2020, 07:44:48 pm
content: Hi,Unfortunately not, loose the interest about - But now it´s actual again as I did some measurements yesterday with poor results.Last year I did only sinewave measurements, yesterday squarewave with horrible results.At a frequency of 100hz, everything seems normal:At 2khz Overshoots appearing:And finally at 22Khz it all sucks up:So what´s going on there...Therefore I had a look in my selfmade schematic and today I open up the "new" current probe.And must admit, there are at least one value of a resistor going through the hall sensors different as drawn from the first probe schematic.Hm-hm...

author: CDaniel
author_rank: Frequent Contributor
timestamp: July 09, 2020, 08:49:47 pm
content: You should probe the signal path inside ... to identify the bad stage or hall sensors

author: Martin72
author_rank: Super Contributor
timestamp: July 09, 2020, 08:57:05 pm
content: I´m on the way, but do it tomorrow.

author: jrf
author_rank: Contributor
timestamp: July 10, 2020, 03:04:24 am
content: Martin,Still can't remember where I have seen your waveforms...BUTTHe third harmonic of 22KHz is being amplified 4x more than the first & inverted!Just did some reading on Bode plots, filters etc..Filters:First order: Signal: no peak. 20db/decade slope.Second order: Signal:always a peak, height dependent on Q. Slope 40db/dec.This one, ~12db/dec so useless as a filter, not designed!SO not a low pass filter as such but some sort of cicuit limitation effect. ie limit of amps.Also stability:"When the magnitude crosses from >0dB to <0dB at a lower frequency than the Phase=180degrees then the system is stable."This does not! Hence Unstable.It makes me wonder if there is not a fault with your clamp. CP-05 is meant to have signal 3db at ~200KHz. Yours is close to that but with a 6db signal increase at 65kHz what use is it! & the phase lag makes any comparison circuit voltage measurements useless past 25kHz. That is meant to be at 200kHz. (One wonders if all those tiny blank capacitors on the board are the correct values. )Increasing the capacitance in the feedback of the final amp would reduce the Q I suspect & move it back to stable.I would try to get another to replicate your tests with their meter.Cheers,John.

author: Martin72
author_rank: Super Contributor
timestamp: July 10, 2020, 04:21:42 pm
content: Hi,As I opened it up, there was not only difference between the resistor values near by the hall sensor connector, also I could see a difference on the feedback-resistors.On the first probe, there was a "tower" of capacitors soldered onto these resistors, here there is only one cap soldered.But first of all I have to fix the probe:While I´ve measured with scope on the op-amp U6, the probe tip came inbetween two pins (+Ub and output) - Now there´s an dc-offset on the output and inputs from the op-amp, I think it´s defective.So I order two new ones, but not mc33028, other one which could work with voltages down to +/- 2.5vdc .Also ordered a smd-soldering tweezer, an assortment of smd capactitors and resistors.....To be continued in the next week.

author: jrf
author_rank: Contributor
timestamp: July 13, 2020, 09:24:07 am
content: Martin,Looking at your drawn circuit you have 560pF capacitors in the feedback of U3a & b in parallel with 10kohm.Correct me if I am wrong but when the freq is such that the impedance of the capacitor = 10k then the gain is 1/2.This assumes there is no feed capacitance. ie none shown.Hence at about 28kHz the gain is halved for both amplifiers.I suspect this affects the 90' phase shift at 25KHz but there must be a change in input impedance as well as the circuit gain is not affected??Reading about ultra sensitive hall chips as made by AKM, linked in post above, running at 1V, have a output RESISTANCE 250-400 ohm.No capacitance mentioned. ie HW-108AI would unplug the hall sensors & apply a signal to R20 to analyse the circuit response. With those circuit values the signal at 28KHz should be attenuated by 1/4. At 400A switch it should have ~unity gain.I note the Chinese use MC33078 at 3V in other circuits I have noted. Some newer Chinese chips have different specs to the 'US' originals. Supply voltage is often 'enhanced' with possibly some loss in distortion noted.I also note the range switched resistor vales do not make sense? ie R28 1K 4A - R27 100 Ohms 40A & 400A open.I would expect 100 ohms=4A 1K=40A 10K=400A or such.Good luckJohn.

author: Martin72
author_rank: Super Contributor
timestamp: July 14, 2020, 10:03:33 pm
content: QuoteIn comparison to my weller tool at work, it´s really a piece of shit - But it does it´s business and the op-amp is desoldered from the pcb."Tomorrow" the replacement should arrive.

author: Martin72
author_rank: Super Contributor
timestamp: July 22, 2020, 10:45:01 pm
content: This thing is so crappy...The trimpot VR3 to adjust the offset of the op07C is.....missing.You have to trim it, there are inputs for it on the op-amp - My former cp05 got it, this one here not (same pcb)...A repaired layer, different resistor in the hall-circuit, different capacitor in the output circuit, missing trimpot...Hands away from this piece of shit !