EEVblog HVP70 Differential Probe

[TheAmmoniacal]

The Teledyne LeCroy is 25 MHz and $495 on Digikey, do they have a 70 MHz version of this?

[madires]

I like the Pintek ones better.

They are clones of Sapphire:
http://www.sapphire.com.tw/notify.pdf

Pintek != Pintech or did I get that wrong?

[Pinkus]

The Teledyne LeCroy is 25 MHz and $495 on Digikey, do they have a 70 MHz version of this?

Yep, wrote that, but it seems I deleted this accidentally (I added it now again).
Of course these 25 Mhz products mentioned by me are internally not identical with an 70 Mhz model - I just spotted, that housing and packaging are identical. I did not see a 70 Mhz in this housing.... but I have not looked too much. Maybe it is an upcoming product.

[nctnico]

I like the Pintek ones better.

They are clones of Sapphire:
http://www.sapphire.com.tw/notify.pdf

No, Pintek is not Pintech. The ones from Pintek are completely different and have 0.75" / 19mm spaced banana sockets:

[mcinque]

Looks like Sapphire SI9010 (about 5200CNY on Taobao, 1485AUD on Trio, tax excl.)

you can find that design under various brands like Pico, Testec and others; probably they are all rebadge of the original (made by? Sapphire?).

[HighVoltage]

If you can sell them for $ 200, you will probably sell a lot of them.

I don't think people realise how much these probes currently sell for. You can't even buy a cheapie ebay or Aliexpress 25MHz job for $200, let alone a quality 70MHz one.

Oh, I overlooked the 70 MHZ
The 25 MHz Pintek sells in Germany for around Euro 250

Looking forward seeing a teardown and review of your EEVblog Differential Probe.

[saturation]

Looks like "Pintech"  have look alikes to both Pintek and Sapphire designs.

http://www.pintech.com.cn/prolist.asp?str=%B2%EE%B7%D6%CC%BD%B0%F4OEM&style=142&idtop=0

The Taiwanese Pintek and Sapphire have always been relatively expensive but they are workhorses, the design are fairly straightforward and ripe for cloning, and there are teardowns of both in the forum archives. 

[bitwelder]

I don't think people realise how much these probes currently sell for. You can't even buy a cheapie ebay or Aliexpress 25MHz job for $200, let alone a quality 70MHz one.

What are the expensive parts of a high voltage probe? (Or, if you open up one, how do you estimate its value?)

[Hideki]

What are the expensive parts of a high voltage probe? (Or, if you open up one, how do you estimate its value?)

The most expensive part is the manufacturer's profit margin. There are no particulary expensive parts inside. They are simply used to selling it at a high price and would like to continue doing so.

[mtdoc]

When I first saw this I thought it said HPV70.  I gasped and thought that's an unfortunate choice of model number since HPV has whole 'nother meaning in the medical world.

Be safe - Don't let your high voltage probe get HPV...

[TheAmmoniacal]

When I first saw this I thought it said HPV70.  I gasped and thought that's an unfortunate choice of model number since HPV has whole 'nother meaning in the medical world.

Be safe - Don't let your high voltage probe get HPV...

Better yet, there actually is an HPV 70 virus (type 70)

[Avacee]

I don't think people realise how much these probes currently sell for. You can't even buy a cheapie ebay or Aliexpress 25MHz job for $200, let alone a quality 70MHz one.

What are the expensive parts of a high voltage probe? (Or, if you open up one, how do you estimate its value?)

Dave's teardown of a Lecroy AP031 25MHz HV Differential probe. a.k.a Sapphire Instruments SI-9001
The components will only be a fractional cost of the design, testing, official validation, customer support, office space, staff wages, staff coffee fund, profit margin from limited sales demographic etc, etc .....

[TheAmmoniacal]

It definitely would be cool to see Dave try to design his own, see how cheap it's possible to go on a differential probe at these specifications. Although I suspect the testing/legalities would make it too expensive or complicated to sell?

[David Hess]

I've taken apart and re-adjusted the attenuator compensation and CMRR of such a thing (apparently something in the input divider changed its behaviour over usage and time).

There's also a downside: no one checks the probes for compensation and CMRR, not even when they get calibrated in a external cal lab :-(
It's perfectly possible to pull a probe out of the storage box with a fresh cal sticker on it and real bad compensation / CMRR. Some months ago, I volunteered an re-adjusted a bunch of them - again no one noticed the change.
The probe simply is used to measure and document the gate signals, no matter if they are misread by bad compensation or CMRR.

...

BTW, the probes I re-adjusted have standard SMT components (1206 planar resistors and caps) for the high voltage divider (several components in series). That's quite cheap ass style, yes it works as long as you don't treat them with high dV/dt rates and you don't have high voltage transients. The standard resistors and capacitors degrade slowly over time (and change their values) if you treat them this way (which is well within their safety ratings, no specs exceeded), leading to bad compensation and CMRR. Then one says, they are worth each dollar they cost - yes maybe in terms of safety they provide, but no, not in terms of performance and long time stability I do expect from such an expensive accessory.

If suitable components are used, then usually it is the printed circuit board material which changes (or starts out bad) screwing up the high impedance compensated dividers.  Tektronix called this "hook" and before qualifying standard fiberglass weave printed circuit board material, early on they used boards made from plastics like polysulfone (amber looking) for their high impedance attenuators and later a white board material that I have not identified yet.

Analog Devices mentions it briefly on page 10 of Analog Dialogue Volume 17, Number 2, 1983 and page 58 of chapter 9 of The Data Conversion Handbook 2005 but the best reference is still the Tektornix article "Getting Rid of Hook - The Hidden PC-Board Capacitance" in Electronics magazine October 12, 1978 which I have available through a bittorrent magnet link.  It is too large for Dave's forum unless I edit it and the scan is in bad enough shape already so I left it alone although I am pretty good at cleaning up old document scans.

I really like these probes, even if I don't need the high safety ratings (other people here need that), but when it comes to real perfomance, it's better to have your own that has never been used by the power people and lab rats before - they simply do not take care of their equipment.

Jim Williams had something to say about maladjusted probe compensation:

"The translation of this statement is to hide the probe when you are not using it.  If anyone wants to borrow it, look straight at them, shrug your shoulders and say you don't know where it is.  This is decidedly dishonest, but eminently practical.  Those finding this morally questionable may wish to re-examine their attitude after producing a day's worth of worthless data with a probe that was unknowingly readjusted." - page 12 of Linear Technology application note 49)

[mtdoc]

Jim Williams had something to say about maladjusted probe compensation:

"The translation of this statement is to hide the probe when you are not using it.  If anyone wants to borrow it, look straight at them, shrug your shoulders and say you don't know where it is.  This is decidedly dishonest, but eminently practical.  Those finding this morally questionable may wish to re-examine their attitude after producing a day's worth of worthless data with a probe that was unknowingly readjusted." - page 12 of Linear Technology application note 49)

He also was a fan of the Tektronix p6046 differential probe but commented on how tricky they were to trim properly after repair. They don't have the high voltage capability of Dave's probe but for someone looking for a budget differential probe, they can be found on eBay for < $100.

[BravoV]

He also was a fan of the Tektronix p6046 differential probe but commented on how tricky they were to trim properly after repair. They don't have the high voltage capability of Dave's probe but for someone looking for a budget differential probe, they can be found on eBay for < $100.

+1 , made this quote while ago when I was waiting to get that probe for years at cheap price.

Btw, I'm not sure these days you can get that P6046 at that price anymore.

[mtdoc]

He also was a fan of the Tektronix p6046 differential probe but commented on how tricky they were to trim properly after repair. They don't have the high voltage capability of Dave's probe but for someone looking for a budget differential probe, they can be found on eBay for < $100.

+1 , made this quote while ago when I was waiting to get that probe for years at cheap price.

Btw, I'm not sure these days you can get that P6046 at that price anymore.

I just checked. There's a few on eBay now for < $100.  This one looks good but is an auction. Opening bid $50.

If I didn't already have one....

[BravoV]

I just checked. There's a few on eBay now for < $100.  This one looks good but is an auction. Opening bid $50.

Interesting, lets see what the closing bid will be as I'm curious too.

If I didn't already have one....

Worst, I have two 

[EEVblog]

I don't think people realise how much these probes currently sell for. You can't even buy a cheapie ebay or Aliexpress 25MHz job for $200, let alone a quality 70MHz one.

What are the expensive parts of a high voltage probe? (Or, if you open up one, how do you estimate its value?)

The leading company in this field, Sapphire, just make diff probes and nothing else. It's their sole source of income, they have to pay for R&D staff etc. Development does not come cheap. 
It not just about the cost of the parts inside.

Sent from my D5833 using Tapatalk

[EEVblog]

There is so much speculation here.
Yes it is a rebadged Sapphire.
It is a new 70MHz model in the old 25MHz case.
No it is not available anywhere else yet that am aware of.
I will be able to sell a 70MHz model for the price of a 25MHz
I don't expect everyone to think it's good value, it's not hobbyist level pricing.

Sent from my D5833 using Tapatalk

[TheSteve]

Looks like my Agilent N2891A is a Sapphire SI-9010A - or at least a slightly customized version of it.

[EEVblog]

All the major scope makers rebadge the Sapphire, they have been the standard for 20+ years.

[nctnico]

I will be able to sell a 70MHz model for the price of a 25MHz
I don't expect everyone to think it's good value, it's not hobbyist level pricing.

Well you can't put a price tag on your own safety! IMHO it is one of those situations where you just have to bite the bullet. Come to think of it... I think the differential probes are among the most expensive probes I have (based on the price I paid for any particular probe).

[amspire]

I used my first probe like this around 1988. I seem to remember it cost about A$800 and the bandwidth might have been 20MHz. In all the time since then, good differential probes have never changed much in price, so there has to be something difficult in designing and making good, safe probes.

You would hope you are buying from a manufacturer the fully tests the probes at the full voltages, as you may have a scope worth thousands of dollars at stake, as well as your safety. And you definitely do not want to spend days following a glitch that turns out to be a probe problem.

Back then, we also had the BWD Powerscope
http://www.ebay.com.au/itm/BWD-880-POWERSCOPE-/121480140048?hash=item1c48c7d510:g:uisAAOSwzOxUWwa8
Which had 4 differential channels designed for safe HV use. Don't know if anyone makes anything like that now.

The one above is missing the 8 special shrouded HV probes, so it will be fun replacing them.

[TheSteve]

Having a good differential probe isn't just about personal safety, it is also about protecting the scope from a connection error etc. If you have a $2000.00(or easily more) scope the probe suddenly doesn't seem so expensive.