Best way to build HV probe/divider

[001]

Hi!

Now I use simple 990M resistor in series with my DMM (input impedance is 10М) to measure 4kV voltage

What way will be the best? I`m confused with a fact what DMM input impedance is a part of voltage divider. It looks unsafe for me 

[med6753]

Two words: DO NOT.  If you value your life and your equipment I don't recommend trying to build up your own high voltage probe.

If you REALLY have the need to measure high voltage spend the money on suitable high voltage probe with the characteristics to match the DMM you are using. 

Edit, here's an example. B&K Precision PR-28 suitable for 10MEG input DMM's.

[tggzzz]

I hope this has nothing to do with a topic you started yesterday https://www.eevblog.com/forum/testgear/where-i-can-read-iec-60601-standard/msg2041996/#msg2041996 which is about medical equipment standards.

001, you are getting a reputation, e.g. https://www.eevblog.com/forum/testgear/what-this-unit-do/msg2040466/#msg2040466 to wit:

001  you have the manual available read it ...    https://www.bkprecision.com/products/power-supplies/1511-digital-discharge-tube-power-supply.html#docsoft

You post tons of questions here and there, you should be able to do some personal search "Google is our friend"  and have your responses before posting something here.


You seems to be a thread starter in many many things ?

[joeqsmith]

Two words: DO NOT.  If you value your life and your equipment I don't recommend trying to build up your own high voltage probe.

High voltage does not have to equal death sentence.  I think my piezo gas grill starter measured over 10KV and I could take a direct hit from it all day long and not die.  Still, not a bad stance to take.  We have no idea what our friend who is 65 year old, living in antarctica, using words like suck, owning several Flukes and can't read their displays, is thinking.   I am not not at all surprised that they are confused.  It may be the first thing they have posted that makes some sense.

What way will be the best?

  It depends what the requirements are.   I posted that link the other day on making attenuators.  Perhaps the video was too complex or long for you to follow?   

1)  Wideband 1KV 100X voltage probes
2)  HV current probe used to look at ESD and other fast events
3) Wideband 40KV voltage probe

Also towards right a discharge probe for the generators (LED is active above 20V or so).   The is used to short out the generators when I am working on the setup.   >20J at over a KV could be lethal. 

[james_s]

Building a reasonably safe HV probe is not rocket science, however it's hard to justify the effort of doing so when you can buy proper HV probes on the used market for reasonable prices. I don't remember what I paid for my Fluke HV probe but I think it was only about $50.

[David Hess]

I`m confused with a fact what DMM input impedance is a part of voltage divider. It looks unsafe for me 

It *is* unsafe and most autoranging DMMs have variable input resistance compromising accuracy.

For safety, a shunt should be included as part of the probe.

[Wolfgang]

Hi,

Frankly, when its only 4kV I would buy one instead of building one. The major problem with homebrew HV probes is proper mechanics and insulation. For a few ten € you can get very decent used 4kV probe from Keysight or Tektronix.

Of course its possible, but its quite some effort if it needs to be a bit wideband.

Remember the old HV mantra: Your first error is your last error.

Have fun, play safe
  Wolfgang

[james_s]

Then again, 4kV is not too hard to contain, it's pretty easy to use a PVC tube with end caps or something of that sort as a housing. When it comes to hobby HV stuff the apparatus is often more dangerous than the test equipment. Either way, be careful.

[coromonadalix]

You have to put high voltage resistors and dividers and provide very good insulation .......  not woth it if you play with your security and your life  ?

But if you're really sure of what youre doing ...   well i did told myself that one time,,   forgot to properly short and discharge an 35kv tv tube screen, my hand were a little moist, i saw a beautiful arc going into my hand, dropped everything on the floor,    my heart did / was going bezerk for an hour.

[Kean]

OP's location is marked as Antarctica.  While I strongly suspect that may not be real, it would explain his difficulty in just buying something off the shelf...

[Hydron]

Maybe he left his kit bag behind in Christchurch and needs to probe a IceCube photomultiplier tube?