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Need help with some measurements.

jw0752

I need some help collecting data about Oscilloscope Probes. I am thinking of making some low frequency Non-Slip probe tip adapters for Oscilloscope probes. With the limited number of Oscilloscope probes with in my reach it does not look like there is any standardization.

 

image

As you can see the two probes that I own each have different diameter probe tips. It would help me plan my project if I could find out what the diameter and length of oscilloscope probes from as many of you as possible. Please measure length of the consistent diameter of the tip and also the diameter itself. I can accept measurement in inches or millimeters. Here is what I hope to be able to build without having to custom make each one.

 

image

 

Your help would be appreciated.

 

John

  • Wanted to help, but sadly, I don't have anything like a wire gauge tool or a set of calipers for precise measurements - but indeed, the profile of the tip and the length/thickness/springiness vary from manufacturer to manufacturer which is why the test "hook" attachments always get muddled up around here or don't fit well ...

     

    That is, unless there's a very simple way to accurately measure them that I didn't think of ...

     

    - Gough

  • in reply to Gough Lui

    Thanks Gough,

     

    I hope you don't mind but I have asked Santa to bring you one of these for Christmas.

     

    https://www.newark.com/duratool/48-500-150/digicaliper-carbon-fibre-150mm/dp/59M5689

     

    John

  • Thanks for the link image.

     

    I was thinking maybe foil + puncturing holes and then scanning it using my high-resolution scanner might actually not be a bad way to do it given the tools I have. Or maybe removing the probe tip for those that are removable and scanning that directly.

     

    I'll let you know if I turn up any results - got some Picoscope, Rigol, R&S, Vellemann and ''generic" probes here which I regularly use. Have some Keysight at the uni lab.

     

    - Gough

  • in reply to Gough Lui

    - I decided to give my improvised method a go - I grabbed a piece of foil and corrugated cardboard, punched the probe tip through the foil into the cardboard and scanned the foil at 4800dpi to judge the size of the depression as a way to measure the probe tip diameter.

    image

     

    My pin diameters measured out to be (using Photoshop to the nearest 0.1mm):

    R&S - 0.5mm

    Rigol - 0.7mm

    Generic #2 - 0.7mm

    Generic #1 - 0.8mm

    Pico - 0.9mm

    Velleman - 1mm

     

    Of course, I'm not sure how accurate it is, but judging from the R&S RT-ZP10 specs which shows the gold plated spring tip (that I'm using) is 0.5mm, I'd have to say that my measurement mode is likely to be accurate "enough". Sorry, no information on pin length as yet image.

     

    - Gough

  • in reply to jw0752

    , for low frequencies, I use a converter, and then normal DMM probes with your anti-slip points.

    image

    When you build add-ons for oscilloscope probes, there's a whatch out apart from different size of probes:

    the tips are delicate, so the insertion power has to be low and the grip power high enough so that the extension does't cause stress on the probe point.

  • in reply to jw0752

    Hi John,

     

    I think you're right, some tuning at the probe end may be needed for high frequencies. I think maybe it would be adequate for 100-200MHz with no tweaks, but I've not attempted it. I've been meaning to try it for ages, I bought the 953 ohm resistor in a couple of sizes and suitable coax/connector a while back. I'll give it a shot in the next week or two, perhaps that could be engineered into a product with your probe on the end, if you can find a way to construct it.

    Plus, using the 50 ohm termination means no need for any tuning at the 'scope connector end at all.

  • in reply to Gough Lui

    You have awesome ingenuity. Thanks for the effort above and beyond the call of duty.

    John

  • in reply to Jan Cumps

    Hi Jan,

    I think that you have the right approach. So far everything about building adapters specific for scope probes looks problematic. Your point about stress on the existing probe tip is well taken. Tips that are 4 mm long and 1 mm wide do not provide sufficient support structure for addition of a potential lever arm in the form of an adapter. I must get myself one of those adapters.

    John

  • in reply to shabaz

    Hi Shabaz,

     

    I look forward to the results of your build.

     

    John

  • in reply to jw0752

    w2aew - a field engineer of Tektronix - has made nice videos on (among other interesting subjects)  probing techniques.

    I use this one at times when direct probing with the pig tail ground is not enough or not practical: