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Offline tvlTopic starter

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Oscilloscope Probe Opinion
« on: February 21, 2019, 07:53:26 pm »
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« Last Edit: March 10, 2019, 12:17:39 am by tvl »
 

Online coppice

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Re: Oscilloscope Probe Opinion
« Reply #1 on: February 21, 2019, 08:05:01 pm »
The cheaper one is only rated for 1000V DC. The more expensive one is rated for 2000V DC. Some of the complaints about the more expensive one are because they received the wrong model of probe, not because of deficiencies in the right model of probe.
 

Online radiolistener

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Re: Oscilloscope Probe Opinion
« Reply #2 on: February 21, 2019, 09:29:11 pm »
I'm using this one:
https://www.aliexpress.com/item/INSTRUSTAR-20MHz-ISDS205B-PC-Based-USB-Digital-Oscilloscope-match-p4100-Oscilloscope-Probe-100-1-Withstand-2KV/32704502182.html

works ok. It has just 6 pF on the input, this is very good to avoid measurement circuit influence from probe capacitance.

I'm skeptic that it can works with 2000 V, I'm using it primary as low capacitance probe. But I think it will works good for 600 V. For higher voltage I suggest to buy branded probe. They more expensive, but this is very dangerous voltage and needs to be handled properly.

Also, note that all probes specifying max voltage for DC! If you're working with AC, there is a graph which shows how max voltage will decrease with higher frequency. This graph is almost the same for all probes. For 2000 V probes max voltage is the following:

0-30..40 kHz = 2000 V
100 kHz = 800 V
1 MHz = 200 V
100+ MHz = 100 V

If you want better branded probe, you can buy TESTEC TT-HV250, it cost for about $48.
https://www.tme.eu/en/details/tt-hv250/oscilloscopes-and-scopometers-acc/testec/

I think, with this one you can measure 2000 V DC with no problem  :)
« Last Edit: February 21, 2019, 10:05:25 pm by radiolistener »
 
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Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #3 on: February 21, 2019, 10:08:17 pm »
I ordered the first one you linked but received something else.   I ran a few tests on it and cut it apart to have a look.   I saw no reason to risk blowing a front end with a probe like this. 

https://youtu.be/v1jJ1Z_fgFU?list=PLZSS2ajxhiQCAQ6gIp6s-WoKiIEb1gHPD

Online radiolistener

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Re: Oscilloscope Probe Opinion
« Reply #4 on: February 21, 2019, 10:40:02 pm »
Regarding to the Hantek, I don't recommend to buy it, their accessories are overpriced and low quality. You can divide their price by 5 (for my local store by 10) to get it's real cost

The second link from the first post is also overpriced, see my message above with the link to aliexpress, where it costs $11. I bought it two years ago for $13, now it even cheaper. This is reliable seller, I bought different cables from him and all is ok. This is not the best probe, so don't expect best quality, but it cheap and works. :)

If you want something better than Chinese quality, then look for TESTEC TT-HV250, its much better, but more expensive.
https://www.testec.de/en/products/product-categories/standard-probes/
« Last Edit: February 21, 2019, 10:55:52 pm by radiolistener »
 

Online 2N3055

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Re: Oscilloscope Probe Opinion
« Reply #5 on: February 21, 2019, 11:12:08 pm »
Testec are good probes, i have several types from them including TT-HV 150 (branded Hameg)
 

Offline tkamiya

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Re: Oscilloscope Probe Opinion
« Reply #6 on: February 22, 2019, 01:06:08 am »
I wouldn't give any credit to Amazon review ratings.  Many people who leave comments have no idea what they have in their hands. 

I also wouldn't use either probes at anything higher than few hundred volts.  Not only could it be danger to front end, it could be danger to myself as well.  A very possible end result is my death! 

Take a look at name brand (mainly HP) on eBay.  Not that you have to buy those but see how different they look, and how they designed in safety. 
 

Offline macboy

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Re: Oscilloscope Probe Opinion
« Reply #7 on: February 22, 2019, 03:44:52 pm »
I ordered the first one you linked but received something else.   I ran a few tests on it and cut it apart to have a look.   I saw no reason to risk blowing a front end with a probe like this. 

https://youtu.be/v1jJ1Z_fgFU?list=PLZSS2ajxhiQCAQ6gIp6s-WoKiIEb1gHPD
Thanks for the destructive testing and teardown. That thing is a piece of junk! I have something similar, but haven't had occasion to use it yet. I guess that I won't.
 

Offline magic

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Re: Oscilloscope Probe Opinion
« Reply #8 on: February 22, 2019, 06:09:58 pm »
For your consideration, voltage vs frequency charts for that Hantek T3100 probe, a slightly more expensive Testec TT-HV250 from Germany and a $500+ Tektronix P5100A.

See how much continuous RMS voltage each probe can take at 100MHz:
Tektronix: 100V
Testec: probably 20V/1.41 is what they meant
Hantek:  gotta be kidding me :-DD

I will stay the hell away from Chinese junk anywhere HV is involved.
 

Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #9 on: February 22, 2019, 06:37:44 pm »
I ordered the first one you linked but received something else.   I ran a few tests on it and cut it apart to have a look.   I saw no reason to risk blowing a front end with a probe like this. 

https://youtu.be/v1jJ1Z_fgFU?list=PLZSS2ajxhiQCAQ6gIp6s-WoKiIEb1gHPD
Thanks for the destructive testing and teardown. That thing is a piece of junk! I have something similar, but haven't had occasion to use it yet. I guess that I won't.

There's a risk for sure.   Glad you found it helpful.   Sadly, there isn't anything out there that I would recommend that is low cost.   

Offline james_s

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Re: Oscilloscope Probe Opinion
« Reply #10 on: February 22, 2019, 06:53:39 pm »
I wouldn't give any credit to Amazon review ratings.  Many people who leave comments have no idea what they have in their hands. 

I also wouldn't use either probes at anything higher than few hundred volts.  Not only could it be danger to front end, it could be danger to myself as well.  A very possible end result is my death! 

Take a look at name brand (mainly HP) on eBay.  Not that you have to buy those but see how different they look, and how they designed in safety.

I think it depends a lot on what you're buying. I've found Amazon reviews to be about the most reliable product reviews out there, I typically look at them and then shop around for the best price. Amazon is not something I associate with test equipment though, and I don't think a lot of knowledgeable engineers buy it from them so you get the hobbyists who don't know any better. In a nutshell, Amazon reviews are probably pretty worthless for a scope probe, but if you're shopping for a vacuum cleaner or a weed trimmer or something they work pretty well.
 

Online 2N3055

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Re: Oscilloscope Probe Opinion
« Reply #11 on: February 22, 2019, 10:29:06 pm »
joeqsmith stated:  Sadly, there isn't anything out there that I would recommend that is low cost.
 
As was mentioned in my initial post, I would like to purchase ONE high voltage probe. The probe would likely be used very seldom and then for voltages only up to 120 VAC .................... possibly at some point in time it may be used for 240 VAC, but highly unlikely.

Not wanting to purchase a piece of junk, what probes would you recommend that might be considered safe and reliable, but yet affordable for such rare usage?

Thanks!

None of mentioned probes are for that. To probe that you need differential high voltage probe that doesn't have any side grounded.
Those you can get from Micsig DP10013 for 150€+VAT all the way to few thousand € depending on specs.
Of course you can get used ones too.
I have Micsig DP10013 and it works well for what it is. For occasional use more than enough.
 

Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #12 on: February 23, 2019, 02:33:25 am »
joeqsmith stated:  Sadly, there isn't anything out there that I would recommend that is low cost.
 
As was mentioned in my initial post, I would like to purchase ONE high voltage probe. The probe would likely be used very seldom and then for voltages only up to 120 VAC .................... possibly at some point in time it may be used for 240 VAC, but highly unlikely.

Not wanting to purchase a piece of junk, what probes would you recommend that might be considered safe and reliable, but yet affordable for such rare usage?

Thanks!

None of mentioned probes are for that. To probe that you need differential high voltage probe that doesn't have any side grounded.
Those you can get from Micsig DP10013 for 150€+VAT all the way to few thousand € depending on specs.
Of course you can get used ones too.
I have Micsig DP10013 and it works well for what it is. For occasional use more than enough.

When I saw the the original post with a 2KV 100MHz single ended probe, I thought I understood what you were after.   Perhaps attempting some HV switching supply designs at fairly low energy levels.  I think I was WAY off with that guess.  :-DD :-DD    With this new post I now I suspect you just want to look at your AC lines in your home with a scope for some reason or another.  50-60Hz rather than DC to 100,000,000Hz.  Lots of Joules vs a couple of Joules.   CAT nothing vs CAT II or who knows, maybe III :-DD :-DD    This is a prime example why I seldom will make a recommendation.

If it were me and I wanted to look at the AC lines with a scope, which I have done, I would use a decent transformer.    I found one that would get me a fair number of harmonics.   I used it along with a LEM sensor to measure power.   If you would like to know more about it, I did post a video. 

I was looking for something more along the lines of your original post.  Being a bit of an electronics hobbyist, I decided to make my own set of two.  They work pretty good for being home made.   Are they safe? NO! Not for AC mains work but I have measured some pretty high frequency KV+ signals with them and have little concern I will damage my scope using them.

https://youtu.be/04I7nHA_HxM

Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #13 on: February 23, 2019, 03:05:46 am »
If you would like to see some of the other probes I have put together, I have a playlist for them.  None of these are safe to use to look at AC mains.   They are not certified and I am just some guy playing with electronics.   Still they may provide you with some idea about how the different probes work.   

https://www.youtube.com/playlist?list=PLZSS2ajxhiQCAQ6gIp6s-WoKiIEb1gHPD

Online radiolistener

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Re: Oscilloscope Probe Opinion
« Reply #14 on: February 23, 2019, 11:51:36 am »
2KV 100MHz single ended probe

2 kV @ 100 MHz is a crazy power, especially if source impedance is 50 Ohm, it will be about 80000 W... :o
I think, if you place chicken near such RF source, it will be fried just in a second even with no need for a direct contact. Like in microwave owen  ???

As you know, 6 pF at 100 MHz is a just 265 Ohm, it means that 6 pF probe should be able to flow 15 kW power through self in order to work with 2000 V at 100 MHz. I think these Chinese probes will just explode from so high power.  :-DD

It is also needed for some kind of electromagnetic protection suit to work with so powerful RF equipment   :D


« Last Edit: February 23, 2019, 12:03:08 pm by radiolistener »
 

Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #15 on: February 23, 2019, 02:56:33 pm »
2KV 100MHz single ended probe

2 kV @ 100 MHz is a crazy power, especially if source impedance is 50 Ohm, it will be about 80000 W... :o
I think, if you place chicken near such RF source, it will be fried just in a second even with no need for a direct contact. Like in microwave owen  ???

As you know, 6 pF at 100 MHz is a just 265 Ohm, it means that 6 pF probe should be able to flow 15 kW power through self in order to work with 2000 V at 100 MHz. I think these Chinese probes will just explode from so high power.  :-DD

It is also needed for some kind of electromagnetic protection suit to work with so powerful RF equipment   :D

Everything is not CW.

I've mentioned before that normally in my hobby when it comes to high voltages,  I work with very small amounts of energy.  The peak power may be high but the average is down in the muck. For example, I made an ESD gun that I use as part of my handheld DMM bench marking.   This gun is capable of putting out somewhere around 4KV at 15A in under 1ns.   Indeed a lot of power but it's all over in a few ns.  The pulse is then repeated every second or so, so the average power is nothing.     Consider a 100MHz probe will have a rise time of roughly 3.5ns.   This probe would not have near enough BW to look at this signal.   Would a cheap probe like the ones shown explode from this transient?  I doubt it.  They could very well breakdown possibly ending the scopes front end.   Do I need any sort of PPE to work with such a device?  Personally, I've never felt the need for it. 

Online radiolistener

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Re: Oscilloscope Probe Opinion
« Reply #16 on: February 23, 2019, 04:00:26 pm »
Would a cheap probe like the ones shown explode from this transient?  I doubt it.

yes, with so short and rare pulses they most likely will not explode due to lack of energy (average).
But I suspect, there is high risk it can be damaged under such conditions.
Because this is definitely out of its specification.
 

Online radiolistener

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Re: Oscilloscope Probe Opinion
« Reply #17 on: February 23, 2019, 04:35:28 pm »
tvl: the problem with mains electricity is that all three lines is not safe (ground, neutral and phase). But passive probe has just one safe contact. The ground contact of probe is not safe, because it is connected to oscilloscope case and  ground contact on it's power cable.

You can use just any cheap transformer to isolate mains lines from your oscilloscope and it will works safe and great. Just connect any cheap transformer to the mains and connect oscilloscope probe to the secondary coil. The transformer should be designed for mains power supply of course. You can check if secondary coil is safe with multimeter - there should not be connection with primary coil. But this way may distort the signal of mains line and you will not be able to see actual amplitude on mains.

You can use differential probe, this is safe and good way, but it is expensive. And since you will use it very rare, there is a real question if you really needs to spend money on that.

You can also use two passive probes and math function on the oscilloscope to show the difference between two probes. Of course you should not connect ground contact of probes. But the result may not be precise and may depends on your oscilloscope math implementation.

« Last Edit: February 23, 2019, 04:43:38 pm by radiolistener »
 

Offline Larry80

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Re: Oscilloscope Probe Opinion
« Reply #18 on: February 23, 2019, 04:45:32 pm »
I would not feel safe around mains circuit, scoping without differential isolated probes..They also come with good set of prongs for this purpose.
 

Offline Fungus

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Re: Oscilloscope Probe Opinion
« Reply #19 on: February 23, 2019, 05:18:53 pm »
As was mentioned in my initial post, I would like to purchase ONE high voltage probe. The probe would likely be used very seldom and then for voltages only up to 120 VAC .................... possibly at some point in time it may be used for 240 VAC, but highly unlikely.

That's not high voltage. A standard 10x probe will handle that -  120V down to 12V, no problem!

(although I'd buy a fixed 10x probe instead of using a switchable one, just in case)

« Last Edit: February 23, 2019, 05:59:11 pm by Fungus »
 

Offline james_s

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Re: Oscilloscope Probe Opinion
« Reply #20 on: February 23, 2019, 07:17:26 pm »
Thanks again to all that have replied!

radiolistener stated:  "tvl: the problem with mains electricity is that all three lines is not safe (ground, neutral and phase). But passive probe has just one safe contact. The ground contact of probe is not safe, because it is connected to oscilloscope case and  ground contact on it's power cable"

First, please know that I do completely understand the issue with NOT using the ground lead of a probe unless one knows EXACTLY where they are placing it. And in my case, with the scope already being grounded, I don't even need to utilize the ground lead and it would therefore likely be disconnected.

However, I do want to protect the scope ............... as well as myself! If a HV probe is nesessary, then I will just need to purchase one. Hopefully, someone will be able to suggest a reasonably priced probe; such as the Micsig DP10013 I'm already considering. However, because of a comment already mentioned, I'm thinking the variable isolated AC transformer may also accomplish what I want while also protecting the scope  ................... which also means that I will be ensuring the ground lead of my passive probe isn't used OR is only placed where it is appropriate when it is required!!!!!!

Again, any and all comments are welcome and very much appreciated!!

You absolutely need to use the ground lead or probe tip grounding always, relying on the scope being grounded you are not going to get a useful measurement. The faster the rise and fall times you're trying to look at, the more critical this is.
 

Online 2N3055

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Re: Oscilloscope Probe Opinion
« Reply #21 on: February 23, 2019, 08:02:01 pm »
It is called electrical circuit for a reason. If you don't ground the probe at measurement point, you will have an unshielded loop that consists of your probe cable, trough scope chassis, out through scope power cable, to the socket, trough common ground on socket installation, through the other socket out into the power cable of DUT, to the chassis of DUT and then to DUT circuit, in whatever way circuit is grounded (or isn't) to chassis. You will pretty much measure everything else except what you need.

Being short of money I understand, all too well. But with physics there are no shortcuts. Wishful thinking is not  going to help.
You need differential probe for that kind of measurement. Differential probing can be made passively (trafo) or actively (diff amp).
In which case, as Joe said, you can use transformer as balun (balanced /unbalanced transformer).

Device you mentioned will have filters and other electronics in its schematic. I doubt waveform will have resemblance to what is on the power grid.
You need a separate transformer, that you will run at low magnetization, with minimum magnetic distortion.
It also needs to be high bandwidth, basically an output transformer from an valve amplifier with at least audio frequency range.

I suggest you to take a look at Joe's video regarding this topic. He explains what he did, how and what kind of transformer he used.

Or try to save up a bit and get that Miscig probe. It has high bandwidth (50+MHz very accurately, and up to 100MHz) and is well made, and also comes with all kind of accessories. And is a proper probe.
You cannot replace that with just any improvisation. And it is safe and will protect your scope.

One thing about differential probes that is not mentioned enough is this: with multimeter we have two probes that we can connect wherever we want, and we measure voltage across that component.
With single ended probe you cannot do that, you always measure absolute voltage as referenced to common power return of the device (the ground).
With scope diff probe you can measure exactly like you would with the meter. To me it was reason enough to have it.  You can look at the waveform across that diode, resistor, capacitor, transistor...

For that reason there are diff probes that are not made for high voltage but also probes to probe fast logic signals, differential busses etc etc.

Regards,
« Last Edit: February 23, 2019, 08:04:44 pm by 2N3055 »
 
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Offline HoracioDos

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Re: Oscilloscope Probe Opinion
« Reply #22 on: February 23, 2019, 08:23:15 pm »
I'm using this one:
https://www.aliexpress.com/item/INSTRUSTAR-20MHz-ISDS205B-PC-Based-USB-Digital-Oscilloscope-match-p4100-Oscilloscope-Probe-100-1-Withstand-2KV/32704502182.html

works ok. It has just 6 pF on the input, this is very good to avoid measurement circuit influence from probe capacitance.

I'm skeptic that it can works with 2000 V, I'm using it primary as low capacitance probe. But I think it will works good for 600 V. For higher voltage I suggest to buy branded probe. They more expensive, but this is very dangerous voltage and needs to be handled properly.
There is another model (P2301) from them. It claims to be up to 5KV for U$35
https://www.aliexpress.com/item/1PCS-wholesale-P2300C-Oscilloscope-Probe-100-1-High-Voltage-Withstand-5KV-300MHz-for-oscilloscope-Tektronix-HP/32352684108.html
 

Offline joeqsmith

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Re: Oscilloscope Probe Opinion
« Reply #23 on: February 24, 2019, 06:04:05 pm »
You could attempt to make a differential probe.   For looking at the mains, you don't need a lot of BW.   I doubt it is worth it.   The parts cost alone may be more than a purchased probe and as you mentioned safety, anything you build I would not consider safe to directly use on mains. 

I've thought about buying one of these wideband HV probes from MICSIG just to see how well they perform.  That last one I made has fairly decent BW but I doubt it is as good. 

Offline HoracioDos

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Re: Oscilloscope Probe Opinion
« Reply #24 on: February 24, 2019, 07:14:29 pm »


I've thought about buying one of these wideband HV probes from MICSIG just to see how well they perform.
It would be very interesting to watch your evaluation.
 


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