New low-cost ($170) 100MHz Differential scope probe from Micsig

[2N3055]

....
My point is, with banana plug instead of fixed wires, it opens up the flexibility and variations at probing the HV test points.

That is correct. I agree.

[toli]

Just noticed these probes a couple of days ago on Aliexpress, and and a quick google search brought me here obviously 

So what are the short term conclusion from these who own the probes? Do they seem to be reliable and worth the money? Or do they start coming apart/exhibit some sort of issues?

I understand there's a problem with the long leads and signals of ~40MHz and over. However, even with a 20MHz limit active on the scope, a 1300V differential probe for 160$ shipped is much cheaper than anything else you can get your hands on. Especially considering the fact it looks quite well designed and built.
Even with the X50 setting, and 130V max input, this can prove quite useful for genera use.

[BravoV]

The negative pulse on the Gate waveform s is probably not real. It there because the differential probe does not have enough common mode rejection ratio, to reject the large dv/dt impressed by the switching.

Is there an easy way to verify and remake a customized test in order to bring out this unwanted artifacts "intentionally" ?

I mean like say do the test using this diff. probe at certain test points or simple custom circuit, and then compared the result again at the same test points vs ordinary passive scope's probes. 

I guess the test points must has low enough (safer) voltage as we're going use common passive scope's probes.

Just a thought.

[David Hess]

Just curious can we get "better" signal integrity at probing, if it is designed with standard female banana input like at DMMs ? Instead of two dangling long and loose wires.

No.

The common mode rejection relies on balanced input impedances.  A single ended probe will just create a greater mismatch in impedance.  Low voltage differential probes can be used this way but only because they have much higher input impedance and are connected directly to the circuit without leads.  They rely on moving the probe as close as possible to the test points for their performance which includes not having input attenuators limiting them to low voltages.

What will work is two identical probes connected differentially which is how the old style high voltage differential probes worked.  They used special probes however which could be calibrated to match each other.  The simple leads on a modern high voltage differential probe are an attempt to make sure they match.

Common high voltage differential probes do *not* have a 1 megohm input resistance designed to work with single ended passive probes so the compensation will be all screwed up.  A special probe adapter that provides a 1 megohm load to the passive probe would be required unless a x1 probe was used.

Would a x1 probe work?  It would add a lot of differential and common mode capacitance.  I am dubious but try it and do the test below.

Is there an easy way to verify and remake a customized test in order to bring out this unwanted artifacts "intentionally" ?

Sure, this is easy.  Connect both leads of the differential probe to the same signal which has the large common mode voltage swing.  In an off-line switching power supply, this would usually be the emitter or source lead of the high side switch.  Since the leads are connected together, they see the same source impedance and zero volts between them.  Anything on the output represents the *best* possible results.  Real results when one lead is moved to the actual signal like the base or gate will be worse so if the best possible results are not good enough, the measurement will be corrupted.

When testing a low voltage active probe or a standard oscilloscope probe, the same test works.  Connect the probe tip to the same point as the ground lead.  Anything besides a flat trace that the oscilloscope shows represents the minimum error that a real signal will produce.

What level of common mode rejection is needed?  A typical off-line switching power supply operates with a peak-to-peak voltage of about 340 volts and a gate voltage of about 10 volts.  That comes out to about 31dB of common mode rejection for a completely corrupted measurement.  10% accuracy would require 51dB of common mode rejection.

An excellent high voltage differential probe can maintain 51dB (355:1) up to about 20 MHz or 17.5 nanoseconds which makes a 100 MHz specification ludicrous.

[Hydron]

I wouldn't say that 51dB CMRR @ 20MHz (well above what any of this type of probe will manage) is essential for them being useful - many circuits will be at mains potential but not at a high frequency potential (e.g. most parts of a PFC boost converter are referenced to the most-negative of the two mains input connections - this will move around a few hundred volts but at 50-60Hz, not in the 100s of kHz).

I do agree that measure the high side Vgs voltage of a high frequency converter will be difficult/impossible for this type of probe - even if the switching frequency is not high, the harmonics from the edge will make a huge mess of any measurement unless high frequency CMRR is very good. For the times I've had to do such measurements I've used a single channel of a battery powered PC-based scope controlled/connected over WiFi, but even with this you need to watch out for oddities due to parasitic capacitance to ground and inductance of the probe coax.

I'm not aware of high voltage diff-probes that do >50dB CMRR at 20MHz other than Tek's IsoVu or some niche products designed for this job (e.g. https://cleverscope.com/news/cs448/ ), and these are both in the $10k USD range (in the case of the Tek, up to $24k per channel!). Do you have examples of what probes you are thinking of?

On a different note, I did some rough checks of different cable lengths with the Micsig probe (temporarily added banana jacks to the probe to allow different length leads to be tested):
- The only way I have to do this is with a cheap spectrum analyser + tracking gen (normalised with a direct cable connection before measurement) so take these with a grain of salt.
- Only a single ended signal could be used as the input, so the -ve lead of the probe was at ground potential
- The tests were done at a 50 ohm input impedance, so 42dB attenuation is expected in 50x mode (=20log((50/(50+75))*(1/50))).
- At low frequencies there are also some measurement artifacts.
- Original probes best match the "medium" length (they are ~58cm plus whatever tip is selected).

The results show that the length of wire makes a large difference to frequency response, and in fact is relied upon for getting anywhere close to the rated bandwidth. Personally I'd be inclined to keep the original leads intact and treat them as 50MHz probes (potentially even mod them to roll off above this!), as while greater bandwidth is potentially possible, controlling peaking would be a nightmare as it depends strongly on physical arrangement of the leads (and probably more stuff too, e.g. source impedance, which was fixed at 50R for this test).

[David Hess]

I'm not aware of high voltage diff-probes that do >50dB CMRR at 20MHz other than Tek's IsoVu or some niche products designed for this job (e.g. https://cleverscope.com/news/cs448/ ), and these are both in the $10k USD range (in the case of the Tek, up to $24k per channel!). Do you have examples of what probes you are thinking of?

The older style ones which used adjustable passive probes could do it or come close if they are calibrated against the source impedance.  I think LeCroy is the only one that makes these now in the form of their DA1855A with one of their fully adjustable differential probe pairs.  The difference is that the probe pair has 8 calibration adjustments for each side and it has to be calibrated against both the differential amplifier and the source.

An oscilloscope with an isolated input is more cost effective and performs better if an unbalanced input impedance and low common mode input impedance is acceptable.  And that just leads back to floating the oscilloscope or preferably floating the device under test if an oscilloscope with isolated inputs or an isolated probe is not available.

Thanks for mentioning Cleverscope.  They make some great looking products.

[frozenfrogz]

Is this thing also usable for low voltage audio applications?
I guess the x50 gain is a bit to much and makes for a bad signal to noise ratio on low voltage circuits - or am I mistaken?
I am still such a bloody n00b in the field of measuring stuff correctly and precise :/

[jacklee]

I'm considering getting two of this probes recently, I thought I should get a discount from Micsig if I can buy two. 
I also saw this guy made a video for this scope, unfortunately, it seems in French language, so most of us would don't understand what he is talking.....
Micsig DP10013

[macboy]

Is this thing also usable for low voltage audio applications?
I guess the x50 gain is a bit to much and makes for a bad signal to noise ratio on low voltage circuits - or am I mistaken?
I am still such a bloody n00b in the field of measuring stuff correctly and precise :/

No, attenuation is too high for low voltage signals.
For low voltage audio frequency range stuff, you can build your own differential to single-ended converter with one or more op-amps (google instrumentation amplifier). With careful tweaking of resistors, you can get the common mode rejection to be very good.

[Hydron]

I'm using mine to look at stuff like gate drive signals (10s of volts swing), and half/full bridge outputs (100s of volts).
For low voltage stuff you might get some use with a sensitive scope (1mV/div or less) and bandwidth filtering to cut down on the noise, but it isn't really ideal.

I also did a quick test with a fast rise time 10MHz source, and could clearly see ringing at the ~70MHz frequency apparent in my earlier post (with the spec-an screenshots). This might be unavoidable with this style of probe (i.e. long leads and attenuation done in the probe body), and should be watched for. I might end up shortening mine so that the problem moves to a higher frequency.

[Pitrsek]

Those isolated banana adapters look neat! I'm thinking about modifying my MicSig diff. probe with an isolated BNC plug so I can attach a 'normal' probe to it or just solder a piece of coax (with isolated BNC) to the DUT.

Aviable as XF-SS/4 from Staubli/Multi contact - not cheap tough - cca 14eur.   

[Insatman]

I bought one of these on Ebay for $145 shipping included.  Seller was asking for $153 but came down just a bit.   Today I tested the rise time of the stock unit without any modification to the leads and using only the provided adapters for the shrouded banana input leads.  The test source is an avalance transistor pulser with a ~700ps Trise and relatively flat top squarewave.  The pulse shape was significantly distorted by the probe setup which is kinda expected as you are introducing a lot of stray capacitance.   Photos of the setup and waveforms are attached.  I may need two or three posts for all the photos.  Note that in the 50x mode I did at least get the promised 3.5ns Trise, although the pulse shape is an overall mess with a lot of ringing.   I'm guessing that usable bandwidth is significantly less and that improvement with shorter leads and better probe tips is possible.

[Insatman]

Next set of photos

[Insatman]

Final photo

[amham]

On sale at Mass drop:  $129.99

https://www.massdrop.com/buy/high-voltage-differential-probe-for-oscilloscope

[bitseeker]

Members-only, eh?

[BrianHG]

Cheapest ebay listing so far 142$:
https://www.ebay.com/itm/Micsig-Oscilloscope-1300V-100MHz-High-Voltage-Differential-Probe-kit-DP10013/282812242682?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20170810094027%26meid%3D94a2bc9a0164464bbc740d7479f9cc57%26pid%3D100855%26rk%3D1%26rkt%3D1%26%26itm%3D282812242682&_trksid=p2349526.c100855.m4779

[Ghislain]

I'm considering getting two of this probes recently, I thought I should get a discount from Micsig if I can buy two. 
I also saw this guy made a video for this scope, unfortunately, it seems in French language, so most of us would don't understand what he is talking.....
Micsig DP10013

I have made a short summary of the most important topics that are being explained, please note I am sticking as closely as possible to what is being said.
Reference video time indications are put in [ ] for easier reference.

1. Introduction
Probe was procured via Banggood and was considered as not being expensive

2. Unboxing [1:00]
Good quality box
Details on the content of the box

3. Closer look at the probe [2:20]
Two flexible input leads however not silicone, quality assessment 'rather good'
USB input (power) and one output
Detailed description of the contents of the leaflet [4:29]
Question raised on CMV (1300V) vs Max Input V to earth (1000V)
Measured current consumption about 200 mA

4. Tests
Considerable noise level, probe needed calibration (procedure is explained in the leaflet) [10:50]
CMRR 50Hz/10MHz sinus with max 20V P2P from a Rigol generator [12:10]
Sensitivity: acceptable for high tension measurements [15:00]
Linearity: green trace on oscilloscope is output generator, yellow trace output probe [16:50], as of 5 MHz slight out of phase noticeable [18:40]
Bandwidth: not really linear, logaritmic view shows a flat response up to about 10MHz [22:40], remark: test conditions suboptimal because of equipment limitations
Mains connected to Siglent 1202X-E, probe X500 [23:25]
Connected to (defective?) switched PSU [25:13]
Safety warning when working with high tension (test setup is not safe!) [26:20]
Internals of the probe [27:35]

5. Conclusion
The probe has its limitations but does a good job [28:50] 

[bitwelder]

Cheapest ebay listing so far 142$:
https://www.ebay.com/itm/Micsig-Oscilloscope-1300V-100MHz-High-Voltage-Differential-Probe-kit-DP10013/282812242682?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20170810094027%26meid%3D94a2bc9a0164464bbc740d7479f9cc57%26pid%3D100855%26rk%3D1%26rkt%3D1%26%26itm%3D282812242682&_trksid=p2349526.c100855.m4779

Looking at it from here, the USD 142 are about EUR 115.
In that case I see a few Chinese/Malaysian sellers offering it at EUR 108.30 (plus minimum 1.50 for shipping), but it seems that the offer is valid only for most of Europe.

BTW, do you see a significant difference or risk between buying directly from Micsig Aliexpress store, or from Banggood, or from some well-established eBay seller?

[17_29bis]

I own a DP10013 and wonder how the following can be explained.

The probe input resistance/capacitance is 10M / 1pF (in diff mode),  I am checking the voltage on the CCFL  connected to the 21" monitor power supply AIP-0121 (it powers  4 CCFL).

I know that this particular size of CCFL  runs at 700V(normal mode) - 1400V (start) Volts and draws about 4-8 mA (the frequency is about 62kHz). It is easy to calculate the equivalent resistance of the  CCFL which is about 150K -200K.

But when I connect the probes of DP10013 to CCFL connector, in a second or so the power supply turns off (due to internal protection) and works just fine if no probe is connected.

During that second I still can capture enough info to see the signal form etc  but I am just curious why the probe affects the work of the power supply - it has much higher resistance and much lower capacitance to make any different but nevertheless it does.

What am I missing here?

Thanks!

[BillB]

Cheapest ebay listing so far 142$:
https://www.ebay.com/itm/Micsig-Oscilloscope-1300V-100MHz-High-Voltage-Differential-Probe-kit-DP10013/282812242682?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20170810094027%26meid%3D94a2bc9a0164464bbc740d7479f9cc57%26pid%3D100855%26rk%3D1%26rkt%3D1%26%26itm%3D282812242682&_trksid=p2349526.c100855.m4779

Looking at it from here, the USD 142 are about EUR 115.
In that case I see a few Chinese/Malaysian sellers offering it at EUR 108.30 (plus minimum 1.50 for shipping), but it seems that the offer is valid only for most of Europe.

BTW, do you see a significant difference or risk between buying directly from Micsig Aliexpress store, or from Banggood, or from some well-established eBay seller?

I picked one up from a different seller on eBay who was willing to negotiate. 

It took a while to show up, but it works fine.  I think the risk is low buying from a proven eBay seller, and most likely, it's probably the same people selling the same stuff on the other sites.

[nctnico]

I own a DP10013 and wonder how the following can be explained.

The probe input resistance/capacitance is 10M / 1pF (in diff mode),  I am checking the voltage on the CCFL  connected to the 21" monitor power supply AIP-0121 (it powers  4 CCFL).

I know that this particular size of CCFL  runs at 700V(normal mode) - 1400V (start) Volts and draws about 4-8 mA (the frequency is about 62kHz). It is easy to calculate the equivalent resistance of the  CCFL which is about 150K -200K.

What am I missing here?

The total load of the probe and wires is likely several pf which at 700V and 62kHz can easely draw a mA extra.

[17_29bis]

The total load of the probe and wires is likely several pf which at 700V and 62kHz can easely draw a mA extra.

I totally understand that. And most likely this is true, because the active resistance of the probe should not affect the work of the inverter much (see the calculations above).

On the other hand if the capacitance of the wires (non-replaceable btw i.e you should use what you have, I twisted them as was suggested), and I am speaking about the wires only because  if the documentation is correct then we can probably neglect 1pF capacitance of the probe, in several times bigger than 1pF then that is kind of strange because all that narrows the application area of this particular probe.

[tautech]

The total load of the probe and wires is likely several pf which at 700V and 62kHz can easely draw a mA extra.

I totally understand that. And most likely this is true, because the active resistance of the probe should not affect the work of the inverter much (see the calculations above).

On the other hand if the capacitance of the wires (non-replaceable btw i.e you should use what you have, I twisted them as was suggested), and I am speaking about the wires only because  if the documentation is correct then we can probably neglect 1pF capacitance of the probe, in several times bigger than 1pF then that is kind of strange because all that narrows the application area of this particular probe.

Consider that low value caps can be made by twisting wires together. If the inverter is that sensitive and running close to it's trip point....... well you get the picture. 
Every measurement affects a circuit !

[nctnico]

The total load of the probe and wires is likely several pf which at 700V and 62kHz can easely draw a mA extra.

I totally understand that. And most likely this is true, because the active resistance of the probe should not affect the work of the inverter much (see the calculations above).

On the other hand if the capacitance of the wires (non-replaceable btw i.e you should use what you have, I twisted them as was suggested), and I am speaking about the wires only because  if the documentation is correct then we can probably neglect 1pF capacitance of the probe, in several times bigger than 1pF then that is kind of strange because all that narrows the application area of this particular probe.

IMHO a high voltage 1:100 probe is more suitable for this kind of measurement since one side of the inverter output and CFL is likely tied to ground anyway.