Oscilloscopes - Questions, Comments and WTF? (and NOLA too!)

laatsch55

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#1
I know more about what's going on at the moon than I know about the everyday use of scopes. I'm sure I'm not the only one here. And I know there are some well versed in scope usage. So instead of having little scope nuggets buried in a 123 page build thread......here we are...
I was hoping this thread could be a general discussion on terminology and understanding. Separate threads for specific procedures or tests may bode well for folks searching for that only....
 

oldphaser

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#2
Here is a list of books and articles. Many have active hyperlinks.

Hopefully, you will find something of use.

If you are interested in specific methods to measure rise time, slew rate, phase, etc using oscilloscopes, I have a list of books and articles for that as well.


Books:

Encyclopedia On Cathode-Ray Oscilloscopes And Their Uses by John Francis Rider and Susan D. Uslan First Edition 1950 or 1955 998 pgs, Second Edition 1959

How To Use Oscilloscopes and Other Test Equipment by R. A. Penfold 1989 112 pgs ISBN: 0859342123 (pprbk)

Know Your Oscilloscope by Paul C. Smith 1958: 1st ed 5th printing 1963
3rd edition 1974 ISBN: 0672211025

Oscilloscope Techniques by Alfred Hass Gernsback Library No. 72 (1958) 224pgs
http://www.tubebooks.org/Books/intro_haas_oscope.pdf

Servicing with the Oscilloscope: A Guide to Testing, Adjustment, and Fault Location in Radio, Television, and Audio Equipment by Gordon John King 176 pgs 1969, 2nd edition 208pgs 1976 ISBN: 040800195X (hrdcvr)

Servicing with the Oscilloscope by Gordon John King
260pgs 1980 ISBN: 0408004835 (pprbk)

Troubleshooting with the Oscilloscope by Robert G. Middleton 1st ed 2nd printing 160pgs 1962 Howard W. Sams Cat No. TOS-1 (see Chapter 12 Testing Audio Amplifiers), 4th edition 256pgs 1980 ISBN: 067221738, 5th edition 256pgs 1987 ISBN: 0672224739

Working With The Oscilloscope by Albert C.W. Saunders 1959, 104pgs 1963, 1968, 2nd edition 104pgs 1972, 112pgs 1975 ISBN:0704200457, 104pgs 1978

99 Ways To Use Your Oscilloscope by Albert C.W. Sanders 1974 ISBN: 0704200783

101 Ways To Use Your Oscilloscope by Robert G. Middleton 2nd edition 192pgs 1968 Howard W. Sams Cat. No TEM-2, 2nd edition 6th printing 192pgs 1971


Articles:

Take The Mystery Out of Probing: 7 Common Oscilloscope Probing Pitfalls To AvoiD 5992-2848

Oscilloscope Fundamentals - Tektronix

Oscilloscope Probe Circuits by Joe Weber First Edition First Printing November 1969 062-1146-00

Power Supply Measurement and Analysis with Bench Oscilloscopes Tektronix Application Note

The XYZs of Using A Scope 1/82 41AX-475B
http://njarc.org/books/XYZs of Using a Scope/XYZs_of_Using_a_Scope.pdf

XYZs of Analog and Digital Oscillocopes
070-8690-01 1st printing February1993

XYZs of Oscilloscopes
http://denethor.wlu.ca/pc320/scope/XYZs_of_Scopes.pdf
http://ecelabs.njit.edu/student_resources/XYZ-Scope.pdf

Oscilloscope Fundamentals Primer Rohde & Schwarz

Using Your Oscilloscope by Leslie Solomon Popular Electronics March 1976 pg 83

Getting the best from your Oscilloscope, Part 2 by D. J. Griffiths Radio Constructor June 1968 pg 700-702

Getting the best from your Oscilloscope, Part 3 by D. J. Griffiths Radio Constructor July 1968 pg 746-750

All About Oscilloscopes Part III Radio Electronics August 1975

All About Oscilloscopes Part IV Radio Electronics Sept 1975 pgs 40-42

What You Need To Know About Oscilloscopes Radio Electronics May 1975 pg 69-81

Getting the Best From Your Oscilloscope Part 2: harmonic waveforms and a.f. amplifier testing with sine waves by D. J. Griffiths The Radio Constructor June 1968 pgs 700-702
http://www.r-type.org/articles/art-125.htm

Getting the Best From Your Oscilloscope Part 3: a.f. amplifier testing with square waves by D. J. Griffiths The Radio Constructor July 1968 pgs 746-749
 

MarkWComer

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#4
I want one, and I also don't know much about them.
I see them on eBay, I'm sure that whatever I buy will need to be serviced.
 

oldphaser

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#5
Don Imlay sent me this link 2 weeks ago:

Vintage scopes are better part 2 by Jim Williams
http://readingjimwilliams.blogspot.com/2012/02/vintage-scopes-are-better-part-2.html


Vintage scopes are better part 1 by Jim Williams
http://readingjimwilliams.blogspot.com/2012/02/vintage-scopes-are-better-part-1.html

I did some additional research and found that Jim's link to the application notes: http://www.linear.com/doclist/?dt=2&au=Jim+Williams no longer works.

So I did a search on archive.org and came up with:

https://web.archive.org/web/20160124234009/http://www.linear.com/doclist/?dt=2&au=Jim+Williams

Ed
 

laatsch55

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#7
I want one, and I also don't know much about them.
I see them on eBay, I'm sure that whatever I buy will need to be serviced.

Mark, years ago (9), I bought a Leader 308LS Dual Trace 20mhz scope for 58.00. And it hasn't mised a day, still a good unit. They're out there, keep shoppin..
 

WOPL Sniffer

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#8
I want one, and I also don't know much about them.
I see them on eBay, I'm sure that whatever I buy will need to be serviced.
Mark, if you were doing like me and Jerry were (Troubleshooting electronics out of a Jet Aircraft), then diving into an old Analog 100MHZ scope may be necessary but for the average dude working out in the shop on amps and pre's etc etc...... A cheap digital scope is MORE than enough. I have yet to NOT be able to signal trace or do general troubleshooting with the Chinee scope I bough in the bay for $100 and it's portable with battery. Pair that with a couple 10:1 (switchable to 1:1) and you'll be able to tackle most anything that comes along.
 

mlucitt

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#10
Here is a simple "how to" as a partial answer to Lee's question (also an attempt to get out of the homework assignment).
1. Power on the scope with no probes, and hopefully get a trace (line) on the display. If no trace, use Beam/Trace Finder or turn up the Intensity.
Make sure Magnifier is off, you may have to adjust Astig if the trace is still fuzzy, or Trace Rotation if the trace is not flat.
2. For Triggering (the trace) select + Slope, place the Level control in the middle, Mode to Auto, and Source to Ch1/Ch2 or Internal. If your scope has Triggering Holdoff, turn it to minimum and select AC Coupling. Play with all the Triggering controls to get a steady trace.
3. Using your scope's controls, get the trace as sharp (usually Focus) and centered (usually <-> or horizontal position) as possible.
4. Adjust the brightness of the line until it is easy to see, but not to bright (usually Intensity).
5. Add a little bit of background light to see the squares (usually Graticule or Screen Brightness).


You should never have to adjust these controls again, they will serve you well if left alone.

6. In Vert Mode, select Channel 1 (this aligns Channel 1 to the Vertical Amplifier), under Volts/Div with the input signal set to Ground, adjust the trace to be in the middle (usually vertical position) of the display.
Speaking of Ground, you will also see DC and AC. DC coupling allows you to measure DC voltage levels and look at AC riding on that DC voltage level, this is good for checking Power Supply rails, but ensure you are using a 10:1 probe and your Volt/Div is set high enough to avoid damaging the scope (usually 100VDC is max). AC coupling puts a small capacitor in line with the input to block the DC level and keeps the trace in the center of the display. So, if your signal is entirely DC, use DC coupling. If you signal is mostly AC, use AC coupling or 'capacitive coupling' to eliminate the DC offset.

7. Repeat step 6 for the other channels (select Channel 2, etc.) but offset the vertical position just a bit so you can see both/all the traces when you select Alt or Chop on the Vert Mode on analog scopes (Alt just alternates between Ch 1 and Ch 2, Chop is more like time sharing of both channels).
8. Once you get the traces calibrated you can calibrate your probe. No calibration for a 1:1 probe, but a 10:1 needs calibration. Set Channel 1 for AC coupling as above. Set the Volts/Div to .1 Volt. Use your 10:1 scope to touch the Calibration or Probe Adj point and you should see a square wave of 1 or 2 Volts (1 grid) on the screen. Use the Time Base (usually Sec/Div) to make the square waves align with the small squares in the display grid. Adjust the collar on the 10:1 probe to make the square waves as 'square' as possible.

9. Finally, to calibrate the display use the Calibration level to display the proper voltage level. Use Vertical Position to get the Channel 1 Trace in the middle of the display. If the Calibration level is 1 Volt and you are using a 1:1 probe, the number of grids the signal covers should be 5, if Volts/Div is set to 5. If you are using a 10:1 probe select Volt/Div to .5 to get the same display. If the grids do not measure 5 vertically, use the ADJ or VAR small red knob to bring the trace equal to 5 grid divisions.
10. Then adjust the period of the square waves. If the Sec/Div period is set to .5 Sec, then each horizontal grid is .5 Seconds of time. Divide one by the Period (.5 Sec) to determine the frequency. If the period is .5 Sec, the frequency is 2 cycles per second or 2 Hertz. If the Calibration level is 2 Hertz, then the square waves should be each covering one grid in the horizontal direction. If your Calibration level signal is a different frequency, adjust the Time Base (Sec/Div) appropriately. Use the small red knob on the Sec/Div control to align the signal horizontally to the correct number of grid divisions.

10. When approaching a circuit with your probe, use AC coupling, set the Time Base to just show a continuous line (rather than a dot moving across the display) and set the Volts/Div to the highest level and work down just like you would with a meter. I like to use Channel 1 to show the input signal to the amplifier and Channel 2 as my probe as I trace the signal path. I expect signal inversion at the Phase Splitter, and signal increases (compared to the input) on the outputs of each of the amplifier sections. When the signal disappears or shows distortion, the output of the component under test becomes suspect.

I hope this helps someone. And if anything is wrong (my dyslexia) let me know.
 
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jbeckva

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#11
Mark, if you were doing like me and Jerry were (Troubleshooting electronics out of a Jet Aircraft), then diving into an old Analog 100MHZ scope may be necessary ...
What'd we need one for anyway? Oh yeah.. those dreaded, nasty, 69B-mutilated scope cards with the big ole square "thing" on one end..

(yuk... LOL)

Don't forget the disc drive 'alinin... :thumbright:
 

laatsch55

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#12
Ok, on a 10X probe attached to the Cal points on the scope for probe compensation, the output on the cal point says 5 volts, it appears on the scope screen as 5 volts.....but that can't be the real square voltage, a 10X probe will need to fed with a half (.5) VOLTS CORRECT????
 

orange

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#13
The manual for the Tek 455M is long and written like rocket science because I think rocket scientists used it...but I think Mark summed it up pretty good.
 

mlucitt

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#14
Yes, the 10X probe has a 9 Meg resistor in series and a 1M resistor in parallel to attenuate the input by a factor of 10. This let's you touch a 100V line and only send 10V to the scope input. With Volt/Div set to 5V, the signal waveform or DC level would take up 2 divisions on the scope display 5V x2 = 10V. Some scopes light up the Volts/Div knob values depending on what type of probe is being used, 1X or 10X.
Some people say unless you are measuring extremely small voltage levels, a 10X probe is preferred because of the attenuation and the better capacitance which allows a higher bandwidth. The rule of thumb there is the probe should have 1.5 times the bandwidth of the scope.
 

orange

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#15
It's only a 200 MHz scope in this case. Which is probably enough for most things, unless you now really want to build rockets.
 

laatsch55

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#16
What I'm asking is, the cal or compensation point on the scope labeled 5 volts is not 5 volts....correct?
 

mlucitt

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#17
Ok, on a 10X probe attached to the Cal points on the scope for probe compensation, the output on the cal point says 5 volts, it appears on the scope screen as 5 volts.....but that can't be the real square voltage, a 10X probe will need to fed with a half (.5) VOLTS CORRECT????
Lee, first put a VOM on the cal point to verify it is outputting 5V peak to peak. 5V at the calibration point with a 10X probe can only be .5V at the scope input (unless the probe is shorted, but you can measure the .5V output at the probe BNC connection before you plug it in). The only way you can read 5 full divisions is if you are 1) in magnify, 2) the CAL knob is turned off of the CAL position, 3) there is a problem in the vertical amplifier.
 

laatsch55

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#18
Ok, because my AP is reading 625 mv at that same cal point, but my Fluke 179 is reading 2.3, granted it's a square wave , so the Fluke should have trouble, although it recognizes 1KHZ

So, you're saying the 5volt tag at the cal point is really 5 volts?
 

Gepetto

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#19
Mine is on my Tek Lee. It says ~5V @ 1KHz so it is approximately 5V. It does not have to be deadly accurate because it is really only there to compensate your probes properly.
 

mlucitt

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#20
The Fluke should be reading less than 5V on the AC scale because the VOM is reading RMS, by calculation it should be 3.54V. The AP may need a ground reference, see if you can connect the AP signal input ground to the ground point on the front (or rear) of the scope.
 
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