Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

Eric R Snow wrote:
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

I'd check the calibration with a DVM (you have to assume that is
reasonably accurate). Simply put the scope across a 9 V battery, and
compare the deflection with the voltage indicated by the DVM.

Leon

Hi Eric, the following website might be of interest to you.
http://www.eng.yale.edu/ee-labs/morse/probe/probe.htm

-------------------------------------------------------------
Eric R Snow - Fri, Feb 10 2006 12:58 pm

The display shows the square wave with 6 divisions vertical and just
over 10 divisions horizontal. Using the VAR knob in the center of the
time/div knob I can adjust the display to show exactly 10 divisions.
When this is done is the display correct? Or is it the calibration bar
that is wrong?
Thanks,
Eric

Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions.

Once you move the VAR knob off the cal position you have
lost the ability to measure time on the X axis or peak voltage
on the Y axis.

So in your case you really don't know how long each division is.
Put the VAR know back on its detent and select the best scale.
Then you can read the period off the X axis. If you vertical
knobs are in the cal position you can read the peak voltage
off the Y axis.

You really should find a book that shows you how to do this.

Eric R Snow wrote:

Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

Assuming that the time base is correct your scope timebase is off. You
should be able to set the sweep knob in the 'cal' position and have the
thing line up exactly. There will probably be an internal adjustment.

I'd try to get a manual for that scope, and a time standard that'll give
you a second opinion.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

On Fri, 10 Feb 2006 13:01:06 -0800, Tim Wescott
wrote:

Eric R Snow wrote:

Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

Assuming that the time base is correct your scope timebase is off. You
should be able to set the sweep knob in the 'cal' position and have the
thing line up exactly. There will probably be an internal adjustment.

I'd try to get a manual for that scope, and a time standard that'll give
you a second opinion.
I have ordered the manual. And downloaded a copy from Ig. I am still
looking for a book that is all about using oscilloscopes and is aimed
at beginners.
ERS

Eric R Snow wrote:
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

The time division is correct only when the VAR knob is clicked off.

GWE

On Fri, 10 Feb 2006 11:58:14 -0800, Eric R Snow
wrote:

Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

Your vertical sounds right. Either your reference calibrator, your
sweep timebase or your horizontal gain is off a tad. If you set
the variable timebase to show exactly 10 divisions, then the
horizontal scale really is 0.1 ms/div if the calibator is accurate.
You could check it with a counter if you can borrow one.

The timebase on the calibrator says ~1KHz, so it's probably not
crystal controlled. My counter says mine is running at 986.37 Hz.

Household power is a pretty good reference at 60 Hz. Use a
transformer.

If you have an old digital watch, it'll contain a 32768 Hz
crystal-controlled timebase that is accurate to 50 parts per million
or better, usually considerably better.

Eric R Snow wrote:

The display shows the square wave with 6 divisions vertical and just over
10 divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this is
done is the display correct? Or is it the calibration bar that is wrong?

Do me one favour:
Please don't connect your scope to the mains or then genset. It might
kill you, judging from the questions you ask here.

This bar is labeled as 300 mV 30mA ~1KHz.
~
This means "about". And you will get only about. Noone cares about the
frequency. The rect-wave is for calibrating the Vpp and the compensation
of the probe. Nothing more.


Thanks,
Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Eric R Snow wrote:
Thanks all for the info so far. Now another one. [...]

http://groups.google.com/advanced_se...rb=q&as_qdr=m&

The calibration bar is to calibrate the 10X scope probes. There is a
capacitor on the probe that gives you an adjustment to get a near perfect
square wave. The voltage should be very close but the frequency is rarely
exact. The capacitor probably will have little effect at 1X.
Glenn
"Eric R Snow" wrote in message
...
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

Eric R Snow wrote:

Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric

The var knob should be turned full clockwise for the vertical scale to
be correct. Tektronic scopes have a detent when the var is turned full
clockwise. It seems to be correct from the numbers you gave. If you
assume that the calibration voltage is right, 300 mv., and your
sensitivity is set for 50 mv per division, 300 mv will deflect the
display six divisions.

John

"Eric R Snow" wrote in message
...
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?

I've no clue about the correct answer but you might want to download the PDF
file found here and look it over:

http://www.tek.com/Measurement/cgi-b...=oscilloscopes

which is a primer on scopes by Tektronix. Here's another on probes:

http://ece-www.colorado.edu/~mcclurel/tabcprobes.pdf

Mike

On Fri, 10 Feb 2006 17:12:33 -0800, "Glenn"
wrote:

The calibration bar is to calibrate the 10X scope probes. There is a
capacitor on the probe that gives you an adjustment to get a near perfect
square wave. The voltage should be very close but the frequency is rarely
exact. The capacitor probably will have little effect at 1X.
Glenn
"Eric R Snow" wrote in message
.. .
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?
Thanks,
Eric


Thanks Glen. That makes perfect sense. The probe came with
instructions to clip it to the bar and adjust the probe with a plastic
screwdriver that came with the probe.
Eric

On Sat, 11 Feb 2006 00:47:40 +0100,
(=?ISO-8859-1?Q?Nick_M=FCller?=) wrote:

Eric R Snow wrote:

The display shows the square wave with 6 divisions vertical and just over
10 divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this is
done is the display correct? Or is it the calibration bar that is wrong?

Do me one favour:
Please don't connect your scope to the mains or then genset. It might
kill you, judging from the questions you ask here.

This bar is labeled as 300 mV 30mA ~1KHz.
~
This means "about". And you will get only about. Noone cares about the
frequency. The rect-wave is for calibrating the Vpp and the compensation
of the probe. Nothing more.


Thanks,
Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige
Greetings Nick,
Why might I be eletrocuted by plugging in the scope to the mains and
then touching the probe to the hot lead from the AC generator? If I'm
isolated from the power where does the danger come from? Look, I
respect electricity and am not going to touch any live wires. I
realize that 'scope case is grounded. I'm serious Nick. If I take the
proper precautions when working with lethal power what is the danger
that I'm not seeing?
Thanks,
Eric

Eric R Snow wrote:

Why might I be eletrocuted by plugging in the scope to the mains and
then touching the probe to the hot lead from the AC generator?

First:
Because probes normaly only have an isolation voltage of 400V. I already
hear your answer. But it is wrong.

Second:
You have to connect the probes GND somewhere. And this is where your
problems start.

Your question is OT here. It doesn't matter that much, because there is
more OT than OT (on-topic) here. But in your case, it matters. You might
get stupid answers. So please ask in an electronics group. They will
tell you solutions that are quite save.

BTW:
Don Foreman gave you a save answer.


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

For accurate calibration of the hor. sweep, you need either a frequency
counter or calibrated [crystal controlled] signal generator to sync the
signals with. A dual trace scope is handy for this.
Bugs

On Sat, 11 Feb 2006 08:39:19 +0100, (Nick Müller)
wrote:

Eric R Snow wrote:

Why might I be eletrocuted by plugging in the scope to the mains and
then touching the probe to the hot lead from the AC generator?

First:
Because probes normaly only have an isolation voltage of 400V. I already
hear your answer. But it is wrong.

Second:
You have to connect the probes GND somewhere. And this is where your
problems start.

Your question is OT here. It doesn't matter that much, because there is
more OT than OT (on-topic) here. But in your case, it matters. You might
get stupid answers. So please ask in an electronics group. They will
tell you solutions that are quite save.

BTW:
Don Foreman gave you a save answer.


Nick
I know Nick. I saved it.
Thanks,
Eric

On Fri, 10 Feb 2006 20:36:01 +0000, Chuck Sherwood wrote:

Using the VAR knob in the center of the time/div knob I can adjust the
display to show exactly 10 divisions.

Once you move the VAR knob off the cal position you have lost the ability
to measure time on the X axis or peak voltage on the Y axis.

So in your case you really don't know how long each division is. Put the
VAR know back on its detent and select the best scale. Then you can read
the period off the X axis. If you vertical knobs are in the cal position
you can read the peak voltage off the Y axis.

You really should find a book that shows you how to do this.

From reading the original post, it sounds like the time-base is spot-on,
and the cal. oscillator is a little under 1 KHz. 10 X .1 ms = 1 ms, and
1/1ms = 1Khz.

Cheers!
Rich

On Fri, 10 Feb 2006 12:20:43 -0800, Buy_Sell wrote:

Hi Eric, the following website might be of interest to you.
http://www.eng.yale.edu/ee-labs/morse/probe/probe.htm

------------------------------------------------------------- Eric R Snow
- Fri, Feb 10 2006 12:58 pm

The display shows the square wave with 6 divisions vertical and just over
10 divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this is
done is the display correct? Or is it the calibration bar that is wrong?
Thanks,
Eric

I don't know what the "calibration bar" is, but if you're talking about
that little loop, the frequency isn't guaranteed to be accurate: in
'~1000Hz', the '~' means "approximately".

If the scope is in cal, then the sweep is calibrated when the var. knob is
turned all of the way clockwise, until the detent clicks.

What it's showing you is that your internal calibrator isn't calibrated
for frequency, which it says right on the front panel: " ~1000Hz ", so
it's not "wrong", either.

Hope This Helps!
Rich