Doug Ford shows us how he designed his own 1000:1 high voltage oscilloscope probe.
http://www.dfad.com.au

and the Oscilloscope probe tutorial:
http://dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf

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By YTB

24 thoughts on “Eevblog #85 – high voltage oscilloscope probe design”
  1. Avataaar/Circle Created with python_avatars DDS (DIY Domótica Solar) says:

    Hi, thanks a lot for your video. In order to check the wave of an inverter or mains, is it ok to use a step down transformer 240/24 ? Will it smooth or disturb the 50/60Hz signal ? What about armonics ? Thanks.

  2. Avataaar/Circle Created with python_avatars Hank White says:

    Question please…. When you connect your scope probe, do you set it for x1 or x10???? the resulting multiplier would also be selected in the scope, (the 1000x option) I have a small bunch of 1000Mohm 10 KV 1 watt resistors and if I was mostly using for DC voltages, could placing one of these in series with the scope probe and with the scopes impedance being ~1 Mohm, would this provide satisfactory readings with the scope probe set to x1 and the 1000Mohms would be very roughly a 1000 to 1 ratio??? I did try this for my DVM with 2 1000Mohm 10KV 1 watt resistors in series and this worked out to about a 200 to 1 ratio since my Fluke has a typical-measured, 10 Mohm internal resistance and my reading were very close to what was expected, (the Fluke is considered to be a x1 device)…. It would not be elegant, but do you think a similar hook up for my scope would suffice?? Thanks for any explanations you may provide…. Hank

  3. Avataaar/Circle Created with python_avatars Tedys Electronics Tech Channel Я says:

    nice

  4. Avataaar/Circle Created with python_avatars Los C says:

    Awsome vid…..ur links dont work

  5. Avataaar/Circle Created with python_avatars Edw590 says:

    But can we hold the probe in our hands while measuring? Only copper there doesn't feel it's isolated. How should we isolate it? Normal plastic would do? Or it wouldn't be enough?

  6. Avataaar/Circle Created with python_avatars Jason Day says:

    The birds have to sing for their supper.

  7. Avataaar/Circle Created with python_avatars Little Clem says:

    Who are you and what have you done with Dave ?….lol

  8. Avataaar/Circle Created with python_avatars Cheyenne River says:

    Hey Dave, this is excellent! I'm not much of an electronics guy, mostly mechanical, but I do need to do an increasing number of electronics projects these days. So I was wondering if you have an EEVblog # that deals with how to Protect a Probe from a voltage spike? Thing is, I made a make-shift probe for probing vehicle secondary ignition signals, and if the coil or wire has leaks, a 30kv spark will jump into the probe tip and fry the scope. It's an inductive pickup of sorts, so it's not designed for direct electricity. So I was wondering how to make some kind of shunt or protection for those sparks. Got a blog on doing that? Thanx!

  9. Avataaar/Circle Created with python_avatars Byron Watkins says:

    For divide by 1000, you should consider two divide by 32 stages. Also, you can provide an inner shield connected to the probe if your HV has low impedance; this increases input capacitance, but maintains your HF response.

  10. Avataaar/Circle Created with python_avatars april segura says:

    Dear sir
    I have a Philips pm 3200 0 – 10 MHz osiloscoop but i dont have the PROBES can you pls help me out with the chematic of the probes . Kinds regards

  11. Avataaar/Circle Created with python_avatars Mohammed Jawad For Electronics and Physics says:

    that sparrow make me mad 😒

  12. Avataaar/Circle Created with python_avatars James skippinhopper says:

    YEP!!!

  13. Avataaar/Circle Created with python_avatars Matthias H. says:

    Thank you very much for this video

  14. Avataaar/Circle Created with python_avatars c muller says:

    I just found that old video and immediately recognized the voice. Hey it's the microphone guy!

  15. Avataaar/Circle Created with python_avatars Laharl Krichevskoy says:

    Just checking my Favorites list, saw this one down the bottom of the list. Salutations from the year 2018.

  16. Avataaar/Circle Created with python_avatars Greg Feneis says:

    Whoa, Dave. This one's pretty old.

  17. Avataaar/Circle Created with python_avatars Jean Pierre Daviau says:

    We would have liked seeing it tested.

  18. Avataaar/Circle Created with python_avatars Jean Pierre Daviau says:

    The red cable is a high voltage cable? Does it have a ground wire?

  19. Avataaar/Circle Created with python_avatars Gear Wrench87 says:

    what happens if you put two 10:1 attenuators in series? does it make it 20:1?

  20. Avataaar/Circle Created with python_avatars RepairAllTV says:

    ????

  21. Avataaar/Circle Created with python_avatars Alperen Alperen says:

    10 puff?

  22. Avataaar/Circle Created with python_avatars Michael Nobibux says:

    Cool,but good probes use coax with a resistive center conductor to reduce ringing when used with a high impedance scope input.A resistive conductor distributes the total resistance (usually around 100-200 ohms) over its length.A lumped (discrete) resistor on the end of a piece of regular coax will not noticeably reduce ringing.Also a hi-Z probe should be well shielded and then there is the 'high voltage' issue….

  23. Avataaar/Circle Created with python_avatars Ele says:

    Great idea and all but, with all the respect, half of the speech I did not understand, could you tell me please what is that "tail wire" for? and how this unit is attached to the oscilloscope and the probe? I just got part of the description… Thanks in advance.

  24. Avataaar/Circle Created with python_avatars 08Ultrasonic says:

    I'm interested by the cal factor. What does this represent exactly? Is it the ratio of input to output voltage?
    I assume that you'll be attaching your probe to an oscilloscope, which will have 10-15pF capacitor and a 1M ohm resistor within that scope. It looks like you've omitted that out of your design, which also might be a reason why the cal factor alters at 200Hz.

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