Author Topic: Learning to use an Oscilloscope (again)  (Read 1968 times)

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SparWeb

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Learning to use an Oscilloscope (again)
« on: March 13, 2021, 11:52:24 PM »
I have never actually learned how to use one of these properly, I've just "used" them a few times before.  A few years ago I bought an old one at an auction (Tektronix 422).  Could have been made in 1969. I've really just played around with it, not really set it up to take accurate measurements or even have a proper set of probes.

It came with its original 10X probe, but now I have a few more.  I got another one to compare whether I like using that. 
Some probes aren't very expensive, but maybe you get what you pay for, so I'll see how it goes.

First thing to do was to get a copy of the manual.  On an old gadget like a 60's o'scope like this, you would think that's hard to do.  Nope.  Lots of faithful followers of Tektronix gear are dedicated enough to publish wiki pages and keep libraries of the old manuals; maintenance and test manuals too (even the manuals for setting up the crazy super-isolated power supplies that o'scopes need.)

Next to figure out the scaling and the triggering.  That was something I kind of picked up as "obvious" before, but I definitely did NOT know about the scaling built into the probes, and the meaning of all that stuff.  Today I spent most of my time sifting through what I need to know about probes (especially since I have a variety of new ones). 

Eventually I found the reference signal port for the calibration square wave.  Once I learned how to set it up and adjust the probe to flatten the peak of the square wave I got my first idea of what this variety of probes is like.  The old Tek 10X that came with this unit was fine, but in learning what the settings meant I wildly cranked the adjustment screw around anyway.  Just to see what would happen.  The other new probes were fine; very slight tweaks.  Still getting used to what I'm doing, so I had already put away the new probe with the 1x/10x switch when I realized that I had only calibrated it on the 1x setting not 10x and got curious how that would affect the compensation.

Next I think I'll go slap a 555 onto a breadboard to make a few signals to be measured.

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JW

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Re: Learning to use an Oscilloscope (again)
« Reply #1 on: March 14, 2021, 01:00:29 AM »
Sparweb those CRT scopes are really hard to use. A LCD scope uses microprocessors and you can optimize your readings. I have a Fluke 123 and loved it until it needed to be rebuilt but the chip that was replaced didn't work as good, it wasn't a fluke component.

I have been looking at the Chinese scopes on ebay. Im going to buy one soon. will link to it and we can discuss pro's and con's   

Mary B

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Re: Learning to use an Oscilloscope (again)
« Reply #2 on: March 14, 2021, 02:21:41 PM »
Basically the trigger knob is used to get your waveform to freeze on the screen, not familiar with that particular scope but most have a TV sweep trigger that is automatic... for the old CRT TV's.

I just bought a new scope, a Rigol DS1202Z-E 200mhz dual trace scope. Wow is this going to have a learning curve from the Tek LCD I used back in the 2000's. WAY MORE math and other functions built in where it can do all kinds of calculations on your waveform. Displays voltage, frequency, pulse width...

My scope needs are a bit more advanced with working on RF, computers, large screen TV's...

SparWeb

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Re: Learning to use an Oscilloscope (again)
« Reply #3 on: March 14, 2021, 09:11:56 PM »
Found the right combo to trigger properly.  The scope has 2 channels and still getting the hang of what lets one channel or the other be the trigger.  Not a problem.

As I said, I built some circuits with a 555 timer and played around with resistor and capacitor values, tweeking the frequency and the duty cycle.  That worked and measuring frequency from the scope screen matched the expected frequency calculated from the RC values.  So far so good.
« Last Edit: March 14, 2021, 11:08:12 PM by SparWeb »
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
www.sparweb.ca


Mary B

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Re: Learning to use an Oscilloscope (again)
« Reply #5 on: March 15, 2021, 01:07:47 PM »
Anyone remember the Forest Miims mini books on diff subjects?

Here is his 555 timer one, great for learning.

http://www.n5dux.com/ham/files/pdf/Forrest%20Mims%20-%20555%20Timer%20IC%20Circuits.pdf

DamonHD

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Re: Learning to use an Oscilloscope (again)
« Reply #6 on: March 15, 2021, 03:25:38 PM »
Yes!  Gosh, I may still have one somewhere...

There were some others of similar simplicity at the time I think.

Rgds

Damon

PS. The other series I now remember was that by "Bernard Babani", now: http://www.babanibooks.com/bb7.htm
« Last Edit: March 15, 2021, 04:08:25 PM by DamonHD »
Podcast: https://www.earth.org.uk/SECTION_podcast.html

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SparWeb

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Re: Learning to use an Oscilloscope (again)
« Reply #7 on: March 15, 2021, 09:29:36 PM »
Probably a big part of why electronics make sense and is fun to me, I started with Forrest Mims, too.
Look carefully at the book on my desk right now:

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Not hard to find his stuff:

http://www.forrestmims.org/publications.html
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
www.sparweb.ca

JW

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Re: Learning to use an Oscilloscope (again)
« Reply #8 on: March 15, 2021, 10:10:33 PM »
I think at one time I had all the Engineer's Mini-Notebook's from Forrest M. Mims III. Think there were 7. I recently gave my Nephew the Getting Started In Electronics. I figure give it a couple years..;.

Reminds me of the encyclopedia of electronics circuits Vol 1 and 2

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Mary B

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Re: Learning to use an Oscilloscope (again)
« Reply #9 on: March 16, 2021, 01:07:55 PM »
Add in older ARRL Handbooks and you have my mid 70's book shelf in my ham shack/workshop.