Differential Probe

Started by January 23, 2012
```Hi ,

I need to measure 800 volts peak to peak.

I am using the following scope with 300 V RMS spec. mentioned at the
front of the oscilloscope.

I found the following differential probe to do this

http://www.testequity.com/products/573/

My question is that am I going in the right direction with this. Will
the high voltage damage the oscilloscope if I use this probe.

Thanks

Melissa
```
```melissa walraven wrote:

> Hi ,
>
> I need to measure 800 volts peak to peak.
>
> I am using the following scope with 300 V RMS spec. mentioned at the
> front of the oscilloscope.
>
>
> I found the following differential probe to do this
>
>  http://www.testequity.com/products/573/
>
>
> My question is that am I going in the right direction with this. Will
> the high voltage damage the oscilloscope if I use this probe.
>
> Thanks
>
> Melissa
I use a battery operating scope that is all insulated with a 2Kv 250Mhz
probe that only cost me 100 bucks..

THat probe you are looking at does not have enough head room in my
opinion.

But, that is just my opinion.

Jamie

```
```Hi,

What should I do? I am stuck with this oscilloscope.

Melissa
```
```"melissa walraven"
>
> I need to measure 800 volts peak to peak.

** More info - is this voltage referenced to ground or across two points in
a circuit ?

> I am using the following scope with 300 V RMS spec. mentioned at the
> front of the oscilloscope.
>

** The scope can show 80V p-p on the screen and so with a 10:1 probe will
show 800V p-p.

> I found the following differential probe to do this
>
> http://www.testequity.com/products/573/
>
>
> My question is that am I going in the right direction with this.

** Nope.

Probes like that very expensive one are for viewing small differential
voltages in the presence of a large voltage to ground.

Why don't you explain what you are really trying to do ?

...  Phil

```
```melissa walraven wrote:

> Hi,
>
> What should I do? I am stuck with this oscilloscope.
>
> Melissa
if this source you're trying to measure has a common to earth
and you are trying to measure between to points with in, then I would
use 2 Hv 100:1 2KV type probes.. USe channels A and B with the math
functions to get a differential between the two.

One thing to note, you may want to check the common on your scope's
probe BNC in the docs, it is very possible you have isolated inputs.
I own a Regal but I never checked that so I can't be sure.

If you do, you still need a HV probe.

I do own a hand held cheapy scope that does have isolated BNC inputs
and I can directly connect between to points in HV land using the
2K probe I have.. And this is a OWEN 20 mhz scope I do this with.

So you may want to check your scope docs.

JAmie

```
```I am trying to measure the voltage across a capacitor in a RC circuit.
Can this scope do diffenertial measurment with out differential probes
using Channel A - Channel B option?

Melissa
```
```On Mon, 23 Jan 2012 11:55:10 -0800, melissa walraven wrote:

> Hi ,
>
> I need to measure 800 volts peak to peak.
>
> I am using the following scope with 300 V RMS spec. mentioned at the
> front of the oscilloscope.
>
>
> I found the following differential probe to do this
>
>  http://www.testequity.com/products/573/
>
>
> My question is that am I going in the right direction with this. Will
> the high voltage damage the oscilloscope if I use this probe.
>

No, it won't. Read the datasheet.

Only problem is that. since you don't have a TekProbe scope, you will need
an 1103 power supply to go with it, costing 2200 bucks, on top of the
\$1320 for the probe.

Does the Rigol have an A-B facility? If so, a couple of 1000V x100 probes
would be considerably cheaper.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
```
```On Mon, 23 Jan 2012 17:07:47 -0800, melissa walraven wrote:

> I am trying to measure the voltage across a capacitor in a RC circuit.
> Can this scope do diffenertial measurment with out differential probes
> using Channel A - Channel B option?
>

If it has that facility, yes. You'll still need high voltage probes,
though.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
```
```On Jan 23, 2:55=A0pm, melissa walraven <walravenmeli...@gmail.com>
wrote:
> Hi ,
>
> I need to measure 800 volts peak to peak.
>
> I am using the following scope with 300 V RMS spec. mentioned at the
> front of the oscilloscope.
>
>
> I found the following differential probe to do this
>
> =A0http://www.testequity.com/products/573/
>
> My question is that am I going in the right direction with this. Will
> the high voltage damage the oscilloscope if I use this probe.
>
> Thanks
>
> Melissa

OK hopefully people on the group will 'correct' me if I say something
stupid.
1.) 300Vrms is a bit more than 800Vp-p.  (But not much head room left)
2.) With a x10 probe the input to the 'scope is cut down by a factor
of ten, so as long as the x10 probe can handle the voltage it should
be OK.  (Phil A mentioned this already.)  You should read the spec's
3.) Can you make a resistor voltage divider to bring the voltage down
to 'human safe' voltage levels.  I hate hooking in to HV stuff.

George H.

```
```melissa walraven wrote:
> I am trying to measure the voltage across a capacitor in a RC circuit.
> Can this scope do diffenertial measurment with out differential probes
> using Channel A - Channel B option?
>
> Melissa
Yes but you need HV probes, which are a lot cheaper than what you were
looking at.

Look for a couple of cheap 100:1 2KV scope probes.

You use the Subtract function in the scope to get the difference
via the two channels.

Jamie

```