DIY HV CRO probe

[Larry Hirsch]

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.

Regards,

Larry

 

[Klaus Bahner]

What would be the most cost-effective way to protect my Tektronics TDS

digital oscilloscope from possible damage by 2-3KV audio signals? It

High voltage probe?

Klaus

 

[martin griffith]

On Tue, 16 May 2006 07:08:32 +0930, in sci.electronics.design Larry

possible damage by 2-3KV audio signals?

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



martin

 

[Pooh Bear]

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.

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.

Graham

 

[Ian Stirling]

On Tue, 16 May 2006 07:08:32 +0930, in sci.electronics.design Larry

possible damage by 2-3KV audio signals?

where do you get 3KV audio from these days?

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

 

[Robert Baer]

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.

Regards,

Larry

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?

 

[tekamn]

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

 

[Tim Auton]

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?

Obviously not, hence the question. Dumbass.


Tim

 

[GregS]

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).

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.

greg

 

[GregS]

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.

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

greg

 

[ehsjr]

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.

greg

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.

Ed

 

[tekamn]

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