How good is the parallax usb oscilloscope?

Comments

• Martin Hebel Posts: 1,239

  2005-01-11 06:20 edited 2005-01-11 06:20

  Hi Lee,
  For the money and portability, it's a great little scope!
  
  I use it often during class on a touch projection screen for discussing various issues with scope - adustments, triggering, etc - and it relates very closely to a standard scope.
  
  About the only downsides are that it's not extremely fast - 1MHz sampling with a single channel.· Since sampling must be at LEAST twice highest the frequency you want to measure, and typically many more samples for good reproduction, you are looking at maybe a 100KHz maximum frequency. But this far fast enough for any BASIC Stamp or other simple analog/digital applications.
  
  Second:· The input impedance is fairly low· - I think 1Meg ohm.· So your scope doesn't load down your circuit, you want the probe to be at least 10x the impedance of the circuit, which would be about 100K ohm.· I have had problems on occasion where the scope would degrade the signal level, but I do a lot of odd things [noparse]:)[/noparse]
  
  Also, a standard scope, with a 10x probe can measure household voltages (115VAC) - DON'T try it with this scope.· It's great for standard digital levels (5V) and up to 12V or so, but that's about it.
  
  All in all, for $149, I've found it invaluable.· When I was a student I forked out $600 for a scope for home studies.· I wish this had been available then!
  
  All specs were off the top of my head in this reply, so look them over yourself!
  
  
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  Martin Hebel
  
  Electronic Systems Technologies
  Southern Illinois University Carbondale
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  ·
• trend Posts: 112

  2005-01-11 06:40 edited 2005-01-11 06:40

  hmm.. yeah, I don't think I would need to monitor any large loads.. so <12v would be fine.
  
  How is the book that comes with this? Honestly I -thinnk- I understand what a DSO does, I have read a large pdf or 2 on them.. but really lack the knowledge of why I would use them.. so I would need the book to eaase me in , but I would like it to cover some ground also.
  
  thanks for your help! that does bring out some great points [noparse]:)[/noparse]
  
  Lee
• Jon Williams Posts: 6,491

  2005-01-11 13:34 edited 2005-01-11 13:34

  The nice thing about (most) Parallax books is that you can download them and check them out at now charge. Why don't you download our "Understanding Signals" book and see for yourself.
  
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  Jon Williams
  Applications Engineer, Parallax
  Dallas, TX· USA
• Chris Savage Parallax Engineering Posts: 14,406

  2005-01-11 16:42 edited 2005-01-11 16:42

  I think the Parallax Scope is a great entry-level scope, and is perfect for BS2-related applications, since it's specs are well-within what the stamp can do, and most of the things you might connect to the stamp.· That said, at the price, you can't really beat it, either.· About the only problem I have is I need a Powered Hub for my laptop, since running an Optical Mouse, the FTDI USB-232 converter AND the Scope seems to be too much for my crappy Dell's 3-USB ports.
  
  
  
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  Chris Savage
  
  Knight Designs
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• tma Posts: 27

  2005-01-16 16:56 edited 2005-01-16 16:56

  I have found the Parallax scope and Understanding Signals text to be excellent value.
  A great scope for the experimenter and would be hacker
  tma