Oscilloscope Probe Opinion - Page 1
Forum section: electronics / testgear

author: tvl
author_rank: Newbie
timestamp: February 21, 2019, 07:53:26 pm
content: Remove

author: coppice
author_rank: Super Contributor
timestamp: February 21, 2019, 08:05:01 pm
content: 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.

author: radiolistener
author_rank: Super Contributor
timestamp: February 21, 2019, 09:29:11 pm
content: 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.htmlworks 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 V100 kHz = 800 V1 MHz = 200 V100+ MHz = 100 VIf 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

author: joeqsmith
author_rank: Super Contributor
timestamp: February 21, 2019, 10:08:17 pm
content: 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

author: radiolistener
author_rank: Super Contributor
timestamp: February 21, 2019, 10:40:02 pm
content: 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 costThe 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/

author: 2N3055
author_rank: Super Contributor
timestamp: February 21, 2019, 11:12:08 pm
content: Testec are good probes, i have several types from them including TT-HV 150 (branded Hameg)

author: tkamiya
author_rank: Super Contributor
timestamp: February 22, 2019, 01:06:08 am
content: 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.

author: macboy
author_rank: Super Contributor
timestamp: February 22, 2019, 03:44:52 pm
content: Quote from: joeqsmith on February 21, 2019, 10:08:17 pmThanks 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.

author: magic
author_rank: Super Contributor
timestamp: February 22, 2019, 06:09:58 pm
content: 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: 100VTestec: probably 20V/1.41 is what they meantHantek: gotta be kidding meI will stay the hell away from Chinese junk anywhere HV is involved.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 22, 2019, 06:37:44 pm
content: Quote from: macboy on February 22, 2019, 03:44:52 pmThere'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.

author: james_s
author_rank: Super Contributor
timestamp: February 22, 2019, 06:53:39 pm
content: Quote from: tkamiya on February 22, 2019, 01:06:08 amI 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.

author: 2N3055
author_rank: Super Contributor
timestamp: February 22, 2019, 10:29:06 pm
content: Quote from: tvl on February 22, 2019, 09:51:33 pmNone 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.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 23, 2019, 02:33:25 am
content: Quote from: 2N3055 on February 22, 2019, 10:29:06 pmWhen 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.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 IIIThis 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

author: joeqsmith
author_rank: Super Contributor
timestamp: February 23, 2019, 03:05:46 am
content: 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

author: radiolistener
author_rank: Super Contributor
timestamp: February 23, 2019, 11:51:36 am
content: Quote from: joeqsmith on February 23, 2019, 02:33:25 am2 kV @ 100 MHz is a crazy power, especially if source impedance is 50 Ohm, it will be about 80000 W...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 owenAs 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.It is also needed for some kind of electromagnetic protection suit to work with so powerful RF equipment

author: joeqsmith
author_rank: Super Contributor
timestamp: February 23, 2019, 02:56:33 pm
content: Quote from: radiolistener on February 23, 2019, 11:51:36 amEverything 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.

author: radiolistener
author_rank: Super Contributor
timestamp: February 23, 2019, 04:00:26 pm
content: Quote from: joeqsmith on February 23, 2019, 02:56:33 pmyes, 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.

author: radiolistener
author_rank: Super Contributor
timestamp: February 23, 2019, 04:35:28 pm
content: 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.

author: Larry80
author_rank: Contributor
timestamp: February 23, 2019, 04:45:32 pm
content: I would not feel safe around mains circuit, scoping without differential isolated probes..They also come with good set of prongs for this purpose.

author: Fungus
author_rank: Super Contributor
timestamp: February 23, 2019, 05:18:53 pm
content: Quote from: tvl on February 22, 2019, 09:51:33 pmThat's nothighvoltage. 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)

author: james_s
author_rank: Super Contributor
timestamp: February 23, 2019, 07:17:26 pm
content: Quote from: tvl on February 23, 2019, 05:16:15 pmYou 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.

author: 2N3055
author_rank: Super Contributor
timestamp: February 23, 2019, 08:02:01 pm
content: 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,

author: HoracioDos
author_rank: Frequent Contributor
timestamp: February 23, 2019, 08:23:15 pm
content: Quote from: radiolistener on February 21, 2019, 09:29:11 pmThere is another model (P2301) from them. It claims to be up to 5KV for U$35https://www.aliexpress.com/item/1PCS-wholesale-P2300C-Oscilloscope-Probe-100-1-High-Voltage-Withstand-5KV-300MHz-for-oscilloscope-Tektronix-HP/32352684108.html

author: joeqsmith
author_rank: Super Contributor
timestamp: February 24, 2019, 06:04:05 pm
content: 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.

author: HoracioDos
author_rank: Frequent Contributor
timestamp: February 24, 2019, 07:14:29 pm
content: Quote from: joeqsmith on February 24, 2019, 06:04:05 pmIt would be very interesting to watch your evaluation.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 24, 2019, 07:37:33 pm
content: Quote from: HoracioDos on February 24, 2019, 07:14:29 pmI would most likely transient test it after I was done with everything else just to get an idea how it compares with some of the handheld meters I have looked at.

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 24, 2019, 08:02:33 pm
content: Quote from: tvl on February 23, 2019, 03:19:26 pmThat's a shed load of dosh though! I wanted to build a variable AC supply but have been racking my brain over how best to accomplish it for months. A transformer with 4 different outputs and a set of relays was an option but not very adjustable or convenient so my current favourite idea of making a decent 50Hz or 60Hz sine wave and then amplifying it to get the correct voltage and current appears to be the favourite.Unless someone has a better idea......

author: james_s
author_rank: Super Contributor
timestamp: February 25, 2019, 06:57:34 am
content: If you want a variable AC power supply why don't you just buy a variac? Or do you need arbitrary frequency?

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 25, 2019, 08:41:26 am
content: Quote from: james_s on February 25, 2019, 06:57:34 amIt would be helpful to switch frequencies but also current limiting. I think it should be quite doable

author: macboy
author_rank: Super Contributor
timestamp: February 25, 2019, 07:58:39 pm
content: Quote from: cowasaki on February 24, 2019, 08:02:33 pmA signal generator to produce the 50 or 60 Hz sine signal, into an audio amplifier, into a suitable line transformer. E.g. for a 100 W audio amp, you would want roughly a 28 VAC output transformer, used in reverse (driving the secondaries and taking output from the primaries). If it has true dual secondaries then you can drive both of them, one with each channel of a stereo amplifier (but ensure close inter-channel level matching). If it has dual primaries, then you can wire it for 120V or 240V nominal output as needed. You get fine control of the frequency and amplitude, plus you have full isolation due to the use of a transformer. I think most of us have an old outdated receiver or amp sitting in a closet, and a box full of various power transformers. Or it is just me?

author: 2N3055
author_rank: Super Contributor
timestamp: February 25, 2019, 09:05:28 pm
content: What does it has to do with oscilloscope probes, this current discussion on frequency converters? I'm confused. Why frequency converters?

author: james_s
author_rank: Super Contributor
timestamp: February 26, 2019, 04:50:59 am
content: Quote from: macboy on February 25, 2019, 07:58:39 pmMy friend used a large audio amplifier to do that a few years ago, it worked however the amp despite being rated for something like 300W RMS it overheated and blew up twice at considerably less power. He replaced that with a proper AC supply which is similar in essence, linear amplifier in a huge rackmount thing with rows of TO3 transistors on an enormous heatsink.