Society of Robots - Robot Forum
General Misc => Misc => Topic started by: z.s.tar.gz on January 26, 2010, 01:07:29 PM
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I'm looking at getting a 'scope, but I don't know what to look for in one.
I don't have a lot of money, but I don't want to get a piece of junk either.
What would you recommend?
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Hi Zach,
There are probably many others up here that can give you a better answer than I can, but it really depends on what you wish to do with it.
The only scope I have is the Parallax USB Oscilloscope that is part of their understanding signals stuff. Real cheap and did do much of what I needed. If I were buying it now I might have gotten their new PropScope: http://www.parallax.com/Store/Microcontrollers/PropellerTools/tabid/143/ProductID/586/List/0/Default.aspx?SortField=ProductName,ProductName (http://www.parallax.com/Store/Microcontrollers/PropellerTools/tabid/143/ProductID/586/List/0/Default.aspx?SortField=ProductName,ProductName)
But for me these have limitted usefulness. There is only so often that I am looking at analog signals. What has helped me out much much more is a logic Analyzer. I purchased one from saele (http://www.saleae.com/logic/ (http://www.saleae.com/logic/)) and it was probably the best $150 I spent on a diagnostic tool...
Good Luck
Kurt
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When talking about scopes... there is pretty much a basic question....
Budget???
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As absolutely cheap as possible before it becomes not worth the money at all. I really really really don't have several hundred dollars to spend period.
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Yeah, a good and easily usable scope with nice features is going to be expensive. So budget is a big concern. But no one asked another obvious question, what do you want to see with your scope? What are you 'measuring'?
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Then get a USB scope, I don't know If there are any cheap PCI slot scopes any more nowadays...
Anyways, if you can not afford a Hameg or a Tektronix then get a cheap USB scope...
Why? because you are going to need that "save pattern" feature badly...
Don't get one with out this... It isn't worth any money when dealing with digital circuits thus
periodical phenomena are hard to achieve....
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I have seen a lot of cheap USB logic analyzers on the market now. Unless you are looking at analog circuits, not much of a reason to pay over $100 for a true oscilloscope.
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I don't really need one right now, but I don't want to wait until I need one to get one if that makes any sense.
I'd much rather buy smd soldering equipment before I bought a scope with that kind of money though...
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You don't need SMD soldering equipment! Irons are just fine ;D
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The #1 thing to ask yourself is, what frequency signal you wish to measure?
For example, lets say you wanted to measure the PWM from your mcu to a servo.
The shortest PWM width I've seen for servos is about 0.5ms long. Thats 1000/0.5ms = 2kHz.
But a single sample won't tell you the PWM width - you need to take many samples across that width. The rule of thumb is 10 samples (for accuracy within +/- 10%). So you'd need 20kHz for that (or 200kHz for accuracy of +/- 1%).
Use that example to help you calculate the sampling rate that you need.
The price of an oscope goes up with desired sampling rate, and USB oscopes tend to have very low sampling rates. I personally never needed more than ~5MHz (to measure UART), but then again, I've never needed to measure anything really hard-core . . .
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I'm using this one called DiSco http://www.hobbylab.us/ (http://www.hobbylab.us/)
PC USB Oscilloscope DiSco is a great tool for your hobby projects!
In the same box you get Oscilloscope, Logic analyzer, Spectrum analyzer, Recorder and Logic generator with a lot of potential, at an affordable price!
Simply connect the device to the computer USB port, run the Windows application and you can analyze the UART, SPI, I2C and 1-Wire interface signals.
So far its OK, crashes sometimes, but I dont think I could live without it anymore :)
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You don't need SMD soldering equipment! Irons are just fine ;D
I need a variable fine tip soldering iron and a hot air rework station if I want to go for the long haul, which is about 180 bucks.
At the moment, I could get more use out of a good soldering iron than I could out of a 'scope.