Differential Probe

M

melissa walraven

Guest
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.

Scop Link: http://www.tequipment.net/RigolDS1102D.html

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.

Scop Link: http://www.tequipment.net/RigolDS1102D.html

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
Click to expand...
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
 
"melissa walraven"
I need to measure 800 volts peak to peak.
Click to expand...

** 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.

Scop Link: http://www.tequipment.net/RigolDS1102D.html
Click to expand...

** 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.
Click to expand...

** 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
 
Hi,

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

Melissa
 
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
Click to expand...
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.

Scop Link: http://www.tequipment.net/RigolDS1102D.html

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.
Click to expand...
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?
Click to expand...
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 pm, 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.

Scop Link:  http://www.tequipment.net/RigolDS1102D.html

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
Click to expand...
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
on your rigol probes.
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
Click to expand...
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
 
Jamie wrote:
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
Click to expand...
Should this be: '*does not* have a common to earth'?

--Winston
 
On Fri, 27 Jan 2012 10:32:42 -0800, melissa walraven wrote:

I am trying to measure atleast 800 Volts acorss the capacitor. I am
unable to understand that does this scope can do differential
measurement using MATH option A - B. I read the user manual but unable
to understand.
Click to expand...
You apply the A probe to one end, and the B probe to the other end, then
A-B is the *difference* between the ends.

That's what "differential" means.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
 
On Jan 24, 5:10 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
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
Click to expand...
Hi,

Will this be an appropiate probe

http://search.digikey.com/us/en/products/P250/290-1051-ND/274483

I am trying to measure atleast 800 Volts acorss the capacitor. I am
unable to understand that does this scope can do differential
measurement using MATH option A - B. I read the user manual but unable
to understand.

melissa
 
On Jan 27, 1:39 pm, Fred Abse <excretatau...@invalid.invalid> wrote:
On Fri, 27 Jan 2012 10:32:42 -0800, melissa walraven wrote:
I am trying to measure atleast  800 Volts acorss the capacitor. I am
unable to understand that does this scope can do differential
measurement using MATH option A - B. I read the user manual but unable
to understand.

You apply the A probe to one end, and the B probe to the other end, then
A-B is the *difference* between the ends.

That's what "differential" means.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Click to expand...
Where should I connect the Ground of the probes?

melissa
 
melissa walraven wrote:

(...)

Where should I connect the Ground of the probes?
Click to expand...
Both go to the common ground return of your circuit.
You will not need a differential probe if one end
of the capacitor is already grounded.

--Winston
 
On Fri, 27 Jan 2012 11:03:21 -0800, melissa walraven wrote:

On Jan 27, 1:39 pm, Fred Abse <excretatau...@invalid.invalid> wrote:
On Fri, 27 Jan 2012 10:32:42 -0800, melissa walraven wrote:
I am trying to measure atleast  800 Volts acorss the capacitor. I am
unable to understand that does this scope can do differential
measurement using MATH option A - B. I read the user manual but unable
to understand.

You apply the A probe to one end, and the B probe to the other end, then
A-B is the *difference* between the ends.

That's what "differential" means.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)

Where should I connect the Ground of the probes?
Click to expand...
To any convenient zero volts point, If the scope's common mode rejection
in subtract mode is good enough, which I doubt, you might get away with
leaving hem floating.

You *must* make sure that both probes are properly compensated with their
respective inputs. That really affects common mode rejection.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
 
melissa walraven wrote:
On Jan 27, 3:13 pm, Winston<Wins...@Bigbrother.net> wrote:
melissa walraven wrote:

(...)

Where should I connect the Ground of the probes?

Both go to the common ground return of your circuit.
You will not need a differential probe if one end
of the capacitor is already grounded.

--Winston

One end is connected to source and the other end is connected to
resistor.

melissa
Click to expand...
Life would be very much easier if we had a good idea
of the circuit you are using. Please consider using
either AACircuit or LTSpice to post an asciimatic?

View in Courier font:


___
Vdd---|___|-----.
|
|
|
||-+
||<-
-||-+
| Expected 800 V p-p
| || V ___
o----||-----|___|-
| ||
|
|
.-.
| |
| | 0.01 ohms
'-'
|
|
===
GND

Exactly like this, right?



(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


--Winston
 
On Jan 27, 3:13 pm, Winston <Wins...@Bigbrother.net> wrote:
melissa walraven wrote:

(...)

Where should I connect the Ground of the probes?

Both go to the common ground return of your circuit.
You will not need a differential probe if one end
of the capacitor is already grounded.

--Winston
Click to expand...
One end is connected to source and the other end is connected to
resistor.

melissa
 
On Fri, 27 Jan 2012 13:02:59 -0800 (PST), melissa walraven
<walravenmelissa@gmail.com> wrote:

On Jan 27, 3:13 pm, Winston <Wins...@Bigbrother.net> wrote:
melissa walraven wrote:

(...)

Where should I connect the Ground of the probes?

Both go to the common ground return of your circuit.
You will not need a differential probe if one end
of the capacitor is already grounded.

--Winston

One end is connected to source and the other end is connected to
resistor.
Click to expand...
---
This is fairly late to be mentioning that there's a resistor in there
too.

Can you post a sketch of your circuit, please?

--
JF
 
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