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Author Topic: Question on a very old Oscilloscope newbie  (Read 760 times)
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I picked up a very old oscilloscope(http://www.ebay.com/itm/150704628673?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_500wt_1145) with some history behind it. I never used one so I bought it to mess around with to get my feet a little wet.. I really have 2 questions, this device was modular, the dual trace(mistyped in the ad) is a 3a72 with a speed of around 600 khz, and the time base is 2 mhz. So what do these different speeds mean and what speed would this scope be generally called speedwise?

In general what can this oscope really draw out, with what it has can it see things like pwm, I dont have any expectations that a arduino flipping a pin high and low as fast as possible will really show up but I really dont know much about this stuff..


Thanks
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Nice find!

600KHz is the bandwidth of the vertical amplifier.  This is the the max signal content the scope is capable of drawing.  The signals from the arduino board will look rounded because their slew rate is faster than 600KHz.

The time base should be stated in seconds, not Hz.
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for the time base I dug up this article here http://www.barrytech.com/tektronix/vintage/tek2b67.html
so if I understand it seems to operate at 2 microseconds

would all this mean this oscilloscope would sample voltages at 600khz, and the timebase would allow a changing the view down to a view of 2 microseconds?

yeah it seemed a little neat the rm561a seemed to be made from 1962-1969 which would line up with this possibly being purchased and used in the development of the Saturn V for the Apollo program.
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The bandwidth of the trigger path is 2MHz. 

The time base runs from 1µs/div to 5s/div.  The "sweep" is how long the beam spends lighting up the display as it moves across the screen.  So the fastest sweep you can do 10µs (1µs * 10 divisions). 
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okay thanks for all your information, I'm about to work on a IR repeater project and the box I'm working on has a ir sensor for 56 khz, maybe I can use that opportunity to really sit down and figure out how to use this :-).
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A nice buy at the price, especially for a beginner.  Get hold of a booklet on how to use a 'scope and you'll be amused for hours on end discovering how many interesting things you can use it for, not simply "looking" at basic waveforms.

Be aware that you should NOT consider looking at any form of mains or line voltage until you are fully conversant on how to do it safely.  Incorrectly connected you could end up short-circuiting the mains and blowing fuses or, worse, making the scope casing live and hence potentially fatal to the touch.

The 'scope is one of the most useful pieces of test equipment, in many cases even superior to a DVM.
« Last Edit: December 13, 2011, 03:51:39 pm by jackrae » Logged

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I don't think you connected the grounds, Dave.
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One of the best things about analogue scopes is turning off the time base, and going into X-Y mode (and sometimes even Z), when you can create Lissajous figures.
A digital scope will do the same, but analogue scopes give a much nicer display.
Somewhere I have 8080 code for the original Space Wars game, using a pair of 8 bit R-2R DACs.
Hmm, I wonder...
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ohh, once you have an oscilloscope you wont know how you lived without one. i picked up an old leader 20Mhz oscilloscope for $45. just happened to ask the right person at the right time. invest in some good probes. nothing sucks more than looking at the screen only to have your wires fall off.
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What a nice find. Have fun learning to use your new scope. I would encourage you to invest in a set of probes and set them to 1:1. Then poke them on to the various pins of the Arduino to practice viewing the signals. Even though the digital signals from the Arduino will have sloping or rounded edges due to the limited bandwidth of the scope you will still be able to see the changes in the waveform of pins such as the PWM pins as they vary in duty cycle. Just setup the Arduino to slowly vary the brightness of a PWM connected LED and then observe the waveform on the scope. Try setting up a 595 shift register and some leds and then outputting various patterns to the shift register and look at the waveforms on the clock and data pins of the shift register as well as on the led outputs. If you scope is a dual channel model you can display the shift register clock and data lines simultaneously to get a real good look at the timing of the signals.

Please heed the advice on not poking around with mains or other HV circuits until you have had some experience using your scope. The bit about the chassis of the scope becoming 'hot' when probing mains operated equipment is very real. Using an isolation transformer (and the one-hand-in-your-pocket rule ) helps to mitigate the risk when probing live circuits. Stick to the low voltage signals of the Arduino while you are learning. If your Arduino is powered by a wall-wart (or your PC's USB port) then you are safe as well as these device must provide isolation from the mains (at least in North America, not sure about other parts of the world).

As AWOL suggested, put your scope in X-Y mode (or X-Y-Z if it can do it) and drive the horizontal and vertical amplifiers directly with the Arduino PWM pins. I remember doing this using discrete counters and analog amplifiers (way, way before Arduino's) to make various patterns. If you want to delve more into the electronics end of things there are tons of circuits to make simple sine-wave oscillators that you can use to drive the inputs and make the lissajous patterns.

The main thing is to have fun and try lots of different things. You will see your circuits and your software differently through the eyes of your scope. Enjoy!
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jumping in the thread here. =)

I am new to Oscilloscopes as well...

in fact outside of seeing a few on benches at schools 'back in the day'...  I have zero experience with them.

That being said, I was recently given one of those digital DSO nano/pocket scopes.

Sits on the bench.. no clue on even the first step to begin playing with it.


Figured I'd pop in here and see if anyone has some steps or direction for me?

THANKS
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I don't think you connected the grounds, Dave.
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Get your Arduino, and program it with a simple pot driven PWM.
Code:
analogWrite(LEDpin, analogRead(potPin) / 4);
Connect your scope probes to the LED output, and fiddle with the controls until you get a stable trace. Then start playing with the pot.
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