DIY HV CRO probe

What would be the most cost-effective way to protect my Tektronics TDS digital oscilloscope from possible damage by 2-3KV audio signals? It is rated for 300VAC input max.

I don't need to measure the frequency or voltage, only check the waveform for distortion without blowing my CRO.



Reply to
Larry Hirsch
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High voltage probe?


Reply to
Klaus Bahner

possible damage by 2-3KV audio signals?

where do you get 3KV audio from these days? Are DVDs 32 bit audio yet?


Reply to
martin griffith

You could always make a voltage divider I suppose. Probably be fine for just audio.

Farnell sell a 100x probe for a little over £20.


Reply to
Pooh Bear

It's only a megawatt into 8 ohms :) There are electrostatic speakers popping up on ebay fairly regularly, most in need of repair.

Reply to
Ian Stirling

Pray tell where the heck would you even GET 1KV (or larger) audio signals???? And hypothetically speaking, if you had such a source, would you be so ignorant or s*d to connect it to the scope? Would you connect the AC line to your VOM set on ohms? Would you step in front of a train going 60 MPH toward you?

Reply to
Robert Baer

Buy a 100:1 divider probe from Hameg or Farnell. Price is approx. 40 to

60 USD, which is acceptable considerign the costs for a Tek scope.

DIY is possible (check e.g. Sam Goldwasser sites for ideas how to do this), but I would not recommend to risk my health on a DIY probe when a commercial, tested and approved probe is so inexpensive.

The Hameg is save for 2.5 kV guranteed, if you need higher ratings go for a used Tektronix P6013 (up to 12 kV) or 6015 (up to 40 kV).

hth, Andreas

Reply to

Obviously not, hence the question. Dumbass.


Did I really still have that sig?
Reply to
Tim Auton

For one time projects it hardly makes sense to buy a probe. About a dollars worth of resistors will work. I usually wire 1/4 watt carbon resistors with a max of 300-400 volts across each in series. Long term voltage across these requires splitting up the voltage, but for short term work, the voltage could be increased a bit. If one can't figure out the entire rig, I would buy a probe.


Reply to

The requirment didn't mention frequency response, so some simple audio should not be attenuated by much, since there is no compensation given here.


Reply to

You can use a turkey baster as the probe body. I did it years ago. I rolled the resistor string in mylar from an art supply store. I don't remember now how many layers for sure - I think it was 11. Damn good insulation. At the probe end and the top I used RTV to hold the probe wire and the jack. The probe was end just a resistor lead.


Reply to

Hi Greg,

Most DIYers think that it hardly makes sense to buy the the right probe right away. Soem of them noticed that it was the wrong decision - the last thing the note in HV applications.

It's okay to build a HV probe for yourself, as Sam Goldwassrs points and the same recipe you give. As long as you have enough HV experience and you *know* where the critical points are, that is okay.

But the OP has spend money for a Tektornix TDS DSO, which is not a cheap instrument. So I guess there he has a little bit of money left to do things right the first time. Keeps him healthy and the scope too.

just my 2cts of opinion, YMMV.

hth, andreas

Reply to

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