oscilloscope calibration

M

Mike

Guest
Hi there,

Does anybody know of a place somewhere in southern NJ (or closeby area) that
calibrates oscilloscopes? How much does this usually cost? I tried searching
for some places but the closest place is in philly, pa.

Thanks.
 
On Sun, 12 Dec 2004 21:11:08 -0500, "Mike" <no_spam@comcast.net>
wrote:

Hi there,

Does anybody know of a place somewhere in southern NJ (or closeby area) that
calibrates oscilloscopes? How much does this usually cost? I tried searching
for some places but the closest place is in philly, pa.

Thanks.
Click to expand...
I assume you are talking about the voltage and frequency
ranges. If so, you can probably make your own calibrator.
Many scopes have a simple calibrator built in, just a square
wave at 1 volt and 1 kHz or some such. You can use a
crystal and some frequency dividers to get a whole
range of frequencies. Use them to chop the output of a
precision voltage reference. You can also make a
precision divider by matching a series of resistors, or you
can use digital PWM to produce a high-frequency pulse
train with a duty cycle that you can set in steps.

Not only is this a good project, it's a handy thing to have
around the lab.

Best regards,



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
Subject: oscilloscope calibration
From: "Mike" no_spam@comcast.net
Date: 12/12/2004 8:11 PM Central Standard Time
Message-id: <9-ednR1MwIyJZCHcRVn-1g@comcast.com

Hi there,

Does anybody know of a place somewhere in southern NJ (or closeby area) that
calibrates oscilloscopes? How much does this usually cost? I tried searching
for some places but the closest place is in philly, pa.

Thanks.
Click to expand...
Hi, Mike. You might want to call the local junior college or trade school and
ask them where they go for calibration services.

Good luck
Chris
 
On Mon, 13 Dec 2004 11:01:21 -0500, "Mike" <no_spam@comcast.net>
wrote:

Hi Bob,

That definitely does sound like a good project. If I could do it myself, I'd
rather not pay someone else. One of the sellers I came across says that the
frequency of the calibration is 975mhz, and the book actually calls it a
1khz signal. Is that true? Is it bad if the person modifies the internal
circuitry to reflect closer to 1khz?

I have zero experience with scopes... please excuse the ignorance.

Thanks.
Mike
Click to expand...
I don't think the built-in scope calibrators should be relied on too
much for frequency. Their primary purpose is to provide a nice square
wave that you can use when setting the probe compensation on a 10X
probe.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
On Mon, 13 Dec 2004 11:01:21 -0500, "Mike" <no_spam@comcast.net>
wrote:

Hi Bob,

That definitely does sound like a good project. If I could do it myself, I'd
rather not pay someone else. One of the sellers I came across says that the
frequency of the calibration is 975mhz, and the book actually calls it a
1khz signal. Is that true? Is it bad if the person modifies the internal
circuitry to reflect closer to 1khz?
Click to expand...
I'm not sure what device the 975 Hz (probably not milliHertz) refers
to. I don't advise messing with the internal circuitry of the scope,
but of course if you build your own it will be as accurate as the
reference crystal you use. Since scopes are usually just for visual
comparisons (unless you have one of those fancy ones with
counter circuitry built in), you only need to make is as good as you
can resolve on the scope face. The raw accuracy of any crystal
you find will probably be much better than that.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
Hi Mike,

I cobbled one together some years back.

http://www.davidbridgen.com/calbox.htm

If I were to do it again I would probably chop the reference voltage
as suggested by Bob.
 
Thanks.

<dmb06851@yahoo.com> wrote in message
news:1103039623.318051.197550@z14g2000cwz.googlegroups.com...
Hi Mike,

I cobbled one together some years back.

http://www.davidbridgen.com/calbox.htm

If I were to do it again I would probably chop the reference voltage
as suggested by Bob.
Click to expand...
 
Hi Bob,

That definitely does sound like a good project. If I could do it myself, I'd
rather not pay someone else. One of the sellers I came across says that the
frequency of the calibration is 975mhz, and the book actually calls it a
1khz signal. Is that true? Is it bad if the person modifies the internal
circuitry to reflect closer to 1khz?

I have zero experience with scopes... please excuse the ignorance.

Thanks.
Mike

I'm pretty familiar with voltage dividers, series, and parallel circuits, so
I'm sure it's something I can handle. Also, I came across a seller on ebay
that retrofitted the scopes crystal to
"Bob Masta" <NoSpam@daqarta.com> wrote in message
news:41bda716.2084257@news.itd.umich.edu...
On Sun, 12 Dec 2004 21:11:08 -0500, "Mike" <no_spam@comcast.net
wrote:

Hi there,

Does anybody know of a place somewhere in southern NJ (or closeby area)
that
calibrates oscilloscopes? How much does this usually cost? I tried
searching
for some places but the closest place is in philly, pa.

Thanks.



I assume you are talking about the voltage and frequency
ranges. If so, you can probably make your own calibrator.
Many scopes have a simple calibrator built in, just a square
wave at 1 volt and 1 kHz or some such. You can use a
crystal and some frequency dividers to get a whole
range of frequencies. Use them to chop the output of a
precision voltage reference. You can also make a
precision divider by matching a series of resistors, or you
can use digital PWM to produce a high-frequency pulse
train with a duty cycle that you can set in steps.

Not only is this a good project, it's a handy thing to have
around the lab.

Best regards,



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Click to expand...
 
Great idea... thanks.

"CFoley1064" <cfoley1064@aol.com> wrote in message
news:20041213120814.06621.00001757@mb-m15.aol.com...
Subject: oscilloscope calibration
From: "Mike" no_spam@comcast.net
Date: 12/12/2004 8:11 PM Central Standard Time
Message-id: <9-ednR1MwIyJZCHcRVn-1g@comcast.com

Hi there,

Does anybody know of a place somewhere in southern NJ (or closeby area)
that
calibrates oscilloscopes? How much does this usually cost? I tried
searching
for some places but the closest place is in philly, pa.

Thanks.

Hi, Mike. You might want to call the local junior college or trade school
and
ask them where they go for calibration services.

Good luck
Chris
Click to expand...
 
Yes, I meant 975hz -- doh.

Thanks for the input. I wouldn't think of modifying any of the scope
circuitry; I was just baffled by someone else doing it.

Cheers,
Mike

"Bob Masta" <NoSpam@daqarta.com> wrote in message
news:41beebf8.2151000@news.itd.umich.edu...
On Mon, 13 Dec 2004 11:01:21 -0500, "Mike" <no_spam@comcast.net
wrote:

Hi Bob,

That definitely does sound like a good project. If I could do it myself,
I'd
rather not pay someone else. One of the sellers I came across says that
the
frequency of the calibration is 975mhz, and the book actually calls it a
1khz signal. Is that true? Is it bad if the person modifies the internal
circuitry to reflect closer to 1khz?


I'm not sure what device the 975 Hz (probably not milliHertz) refers
to. I don't advise messing with the internal circuitry of the scope,
but of course if you build your own it will be as accurate as the
reference crystal you use. Since scopes are usually just for visual
comparisons (unless you have one of those fancy ones with
counter circuitry built in), you only need to make is as good as you
can resolve on the scope face. The raw accuracy of any crystal
you find will probably be much better than that.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Click to expand...
 
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