When did you first really use an oscilloscope?
Jeff Dege
Posts: 85
When did you first really use an oscilloscope?
I've used them in class exercises, and run through the examples in the manuals, etc. I bought the Parallax USB Oscilloscope and worked through the examples.
But in truth, I've never actually had a question that I recognized as being answerable by an oscilloscope until today.
I'm playing around with using a Javelin in photography. I've rigged a circuit by which it can trigger the shutter on my digital camera, and used this in doing some time-lapse photography. (Not with a great deal of success, yet. I have some issues regarding lighting and post-processing I have to resolve. But the electronics worked perfectly.)
Time-lapse doesn't need a great deal of precision. If you're taking one picture every three seconds, you don't care much about microseconds.
But I intend to extend this to use with high-speed photography. I.e.:
1. Javelin opens camera shutter (in the dark)
2. Javelin moves a stepper, which releases a marble.
3. Falling marble breaks an IR beam.
4. Javelin waits a set time.
5. Javelin triggers short-duration flash strobe.
6. Javelin closes camera shutter.
If you want to catch the marble just as it splashes into a glass of milk, the timing becomes critical - and the lengh of the delays in your control circuits matters a lot.
So when I have the flash trigger built, I'll be using a photodiode and the Parallax USB Oscilloscope to measure that delay. Right now, I'm just testing how long it takes the Javelin to raise a pin. I put channel 1 on pin 1, channel 2 on pin 2, set the trigger on channel 1, then have the Javelin do "CPU.writepin(CPU.pin1, true); CPU.writepin(CPU.pin2, true);" - and measure how long the delay between the rise of channel 1 and channel 2.
The answer is 114.0 microseconds. If my marble has fallen six inches, in an additional 114 microseconds, it will fall an additional 7/1000ths of an inch. Which isn't a lot, but it's twice the duration of the flash itself.
It's not really very exciting, but it's the very first time I used a scope to answer a question I had, instead of a question from a book.
I've used them in class exercises, and run through the examples in the manuals, etc. I bought the Parallax USB Oscilloscope and worked through the examples.
But in truth, I've never actually had a question that I recognized as being answerable by an oscilloscope until today.
I'm playing around with using a Javelin in photography. I've rigged a circuit by which it can trigger the shutter on my digital camera, and used this in doing some time-lapse photography. (Not with a great deal of success, yet. I have some issues regarding lighting and post-processing I have to resolve. But the electronics worked perfectly.)
Time-lapse doesn't need a great deal of precision. If you're taking one picture every three seconds, you don't care much about microseconds.
But I intend to extend this to use with high-speed photography. I.e.:
1. Javelin opens camera shutter (in the dark)
2. Javelin moves a stepper, which releases a marble.
3. Falling marble breaks an IR beam.
4. Javelin waits a set time.
5. Javelin triggers short-duration flash strobe.
6. Javelin closes camera shutter.
If you want to catch the marble just as it splashes into a glass of milk, the timing becomes critical - and the lengh of the delays in your control circuits matters a lot.
So when I have the flash trigger built, I'll be using a photodiode and the Parallax USB Oscilloscope to measure that delay. Right now, I'm just testing how long it takes the Javelin to raise a pin. I put channel 1 on pin 1, channel 2 on pin 2, set the trigger on channel 1, then have the Javelin do "CPU.writepin(CPU.pin1, true); CPU.writepin(CPU.pin2, true);" - and measure how long the delay between the rise of channel 1 and channel 2.
The answer is 114.0 microseconds. If my marble has fallen six inches, in an additional 114 microseconds, it will fall an additional 7/1000ths of an inch. Which isn't a lot, but it's twice the duration of the flash itself.
It's not really very exciting, but it's the very first time I used a scope to answer a question I had, instead of a question from a book.
Comments
KK
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Just tossing my two bits worth into the bit bucket
KK
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The LCD will allow me to program some menus and configuration options, so that I don't, for example, have to redownload just to change the delay between shots when doing time-lapse. But that's a ways away.
All I have right now is the Javelin plugged into a breadboard, with a program that waits for a button to be pressed, and then takes 900 pictures with a three second delay between each.
I first used an Oscilloscope in graduate school, where I was working with sub-picosecond time resolved laser spectroscopy.
My thesis work involved measuring the electron transfer rate of a DNA repair protein called photolyase.
4 seperate lasers were involved in generating the pulse train.
Throw in a lock in amplifier, a CCD array, a couple of boxcar integrators, and all of a sudden you realize how important the Oscilloscope is!
I would love to get my hands on a decent 400 MHz dual channel scope, but my budget is limited.
Do you have any suggestions on where to get a used one?
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I wonder if this wire is hot...
www.visi.com/~jdege/ice-melt2.mpg
awesome!
What did you use to compile all the stills into a single mp3?
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Just tossing my two bits worth into the bit bucket
KK
Post Edited (Kaos Kidd) : 3/28/2006 3:36:54 PM GMT
I have been 'playing around' with oscilloscopes my whole life. I think it started in either a Junior High summer school class of electronics [noparse][[/noparse]about 1960]·or a high school electronics class.
But, have I ever actually used one?
It is embrassing to answer, but no, not really.
I have had a few scopes.
The last one was an old Textronics 'tube scope' with dual inputs and 20Mhz bandwidth, but it was huge and hard to either set up or bring to things.
Recently, I have begun to realize that many of the issues in digital are far more 'scope dependent' than analog and that I should really buy one in order to be able to clean up noise on a circuit and in order to actually get the timing right.
While a VOM is a very useful and important tool, it cannot give you an image of serial data and how clean it is.
For over I year I have been pondering making the investment in a modern up-to-date oscilloscope because my interest and commitment continues to grown as I learn more.
In other words, I am a bit weary of operating with that 'blind area' in my use of microcontrollers.
Still I wonder how many features, what bandwidth, and how many channels are enough?
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
My scope either sits idle or goes through a period of extensive use. It tells me answers I can't get any other way. When my main experimental focus was ham radio, an analog scope was fine because everything was a repeating pattern. However, I needed more bandwidth once I got beyond 30mhz signals.
Moving to microcontrollers changed all that. I considered buying a logic analyzer. But I realize I rarely need to track more than a couple of signals. However, single event tracking is essential when I'm trying to figure out why something isn't working. The tradeoff was that my processors use lower speed clocks so 100mhz is adequate for my work.
I hope the new Tek scope will last me for the rest of my life.
That is the central problem. You can actually see noise rather than guess what is going on. And you can see the rise and over-shoot, too.
So, you are saying 100mhz and Dual Channel is good. What about options?
I was thinking of a computer scope, but I fear that I might have to fool with code and documentation all at the same time. I know I could just jump around in Windows, but are there advantages to 'real' rather than 'virtual' gear?
BTW, the time-lapse photography is Great! ! !· Just another reason to consider buying a scope.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Post Edited (Kramer) : 3/29/2006 2:22:08 PM GMT
I considered and decided not to buy one of the software driven scopes and instead decided for a complete separate unit.
Computers are a source of electrical noise and there are times when I want my scope to operate without that input. Computer, off.
The bigger issue is the "service life" of software. Five year old software is ancient. Operating systems change. Previously supported capabilities aren't. I bought the Tek with the expectation it will meet my needs for at least 15 years. I won't buy a computer operated scope with that expectation. What happens five years from now when Microsoft announces their new XZ operating system and the Stanley Schultz company decides they will no long upgrade software for their old "Schultz II" plug in scope? Maybe Mr. Schultz dies and there is no longer any Stanley Schultz company. You are stuck with a software orphan. Even if I never upgrade the software in my Tek it will continue to work.
I'm confident my Tek scope will continue to provide service well into the future. Tek is the only instrumentation company with a cult following that continues to provide support after the official service life has ended. HP used to have a similiar following. That ended when they began to outsource their equipment and after the Agilent split.
Parallax has shown itself to be very sensitive to customer support. If the past is any indication they will continue to support the Optascope for years to come.
Try this thread, it may answer questions for the hobby user:
http://forum.microchip.com/tm.aspx?m=144413
Post Edited (bobledoux) : 3/29/2006 4:39:49 PM GMT
Absolutely.
I have an old Hitachi analog sitting on the equipment shelf at my desk, holding up a triple output DC power supply.
I use the power supply all the time - in every single circuit I've built since I bought it. I never use the Hitachi scope at all. But it has a visual presence to it that the Parallax USB scope does not - it's an essential part of the decor. Come the annual Halloween party, I turn it on and feed it a signal, so guests can watch the trace.
No evil genius could call his lab complete without one.
(Now I just need to figure out how to build a Van de Graff generator and one of those spark-gap thingies.)
... The Van de Graff generator is simple... and easy... when your ready... [noparse]:)[/noparse]
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Just tossing my two bits worth into the bit bucket
KK
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You can build a Jacob's ladder too. But all of that will play havoc with your computer and test equipment.
I suppose the older and larger, the better presence, like having an old MaxIntosh stero. Lots of heat to.
I personally get nostagic for black phenol plastic and brass electrical fittings. The colors are subdued and sensual.
Useful life is a consideration and the software issue is ever present. Symantec is once again begging their virus up-date and my System Mechanic needs the anual renewal too.
I suppose I should consider the Parallax Scope for a 'virtual' scope in the interim and shop for a good real - best of both worlds and more presence, more status.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan