When is the right time for buying a Scope?

Discussion in 'General Electronics Chat' started by penguin, Sep 14, 2005.

  1. penguin

    Thread Starter New Member

    Sep 4, 2005
    2
    0
    Oscilloscope is must-have test equipment for electronics?

    Then, when is the right time to buy it?

    I'm studying electronics myself for fun and career development. I began to start in automotive service area after finishing a college.
     
  2. n9xv

    Senior Member

    Jan 18, 2005
    329
    1
    When the wife or significant other is away on a buisness trip and OOOPPPS! - - - she left the credit cards behind!

    But seriously,

    Buy a scope at the point when you feel it would greatly enhance your knowledge and learning ability. Really just a matter of what you can afford, and what you expect to do with it. A simple scope good up to 5-MHz can be picked up at a flea market for under $40. A midrange 20-MHZ scope can be had for $150 range. And on up to the lattest tecknologe for well into the $1000 mark.

    1 - - - What type of circuitry do you want to look at?

    2 - - - What frequency range will cover that type of circuitry?

    3 - - - Will it be used for precise measurement "on the job", or just for tinkering/self learning etc?

    That should at least point you in the right direction.
     
  3. Brandon

    Senior Member

    Dec 14, 2004
    306
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    There are programs you can buy for the PC that come with a probe and you basically turn your computer into an oscilloscope. If you have a laptop, you're good to go, light portable oscilloscope. Not only do you have the data there, very easy to export it from the program and into say excel to do some analysis or what not since its all on the PC.
     
  4. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    Sounds a good idea. Any recommendations?
     
  5. Brandon

    Senior Member

    Dec 14, 2004
    306
    0
  6. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
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  7. tonykuphaldt

    Member

    Jan 10, 2004
    14
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    As a teacher, I'm a big fan of having students first learn on an "old school" analog (CRT-based) oscilloscope first before touching a digital scope. My reasons are as follows:

    (1) Cheap analog scopes are usually quite a bit more capable than cheap digital scopes. More bang for the buck on the low end of the price scale, especially if you are considering used equipment.

    (2) Every control is immediately available for viewing and tweaking on an analog scope. Nothing hidden in pull-down menus.

    (3) Analog scopes do not suffer from signal alias (too-slow sampling of input signal), as digital scopes do. This can be VERY confusing for people just learning to use a scope, as it makes high-frequency signals look like low-frequency signals if the sweep speed is set wrong. I've used $1500 Fluke digital scopes that alias, so price is not an assurance you will be immune from such "artifacts" of a digital instrument.

    I've used the free software that turns a PC's sound card microphone input into a crude scope. CRUDE is the operative word here. The resulting "oscilloscope" has a usable frequency range of (only) about 40 Hz to 10 kHz, no DC coupling option, an inherent phase shift between left and right stereo channels (at least with common sound cards), no overvoltage protection for your PC, and no calibration whatsoever on the vertical axis, just to name some of the more significant limitations. There are times when I use this in classroom demonstrations, but only under carefully "rigged" conditions where none of these limitations will be noticed. In other words, you already have to know how to use a scope in order to make sense of what the sound card scope is telling you.

    Having said all this, a good digital oscilloscope is a fantastic instrument, capable of doing things that analog scopes simply cannot. Capturing transient events and generating logs of the same is but one example. However, you will have to have a firm understanding of oscilloscope "basics" before you will be able to appreciate and use the advanced capabilities of a quality digital scope.

    Consider your first oscilloscope the same way you would consider buying your first car: get something simple and cheap that you can learn well on. When the time comes you will be ready to trade up to something better.

    Hope this helps!

    - Tony
     
  8. Brandon

    Senior Member

    Dec 14, 2004
    306
    0
    Web tronics specs for their PC osc. They aren't as limited as you think.

    Specifications

    * Minimum system requirements
    o IBM compatible PC
    o VGA display
    o Free Printerport LPT1
    o Mouse
    o 400 kB free conventional memory
    o Technical data
    o Vertical deflection
    * Sensitivity : 10mV ... 5V/DIV
    * Frequency range : DC to 16MHz
    * Input impedance : 1MOhm // 30pF
    * Input coupling : DC - AC - Gnd
    * Input voltage : max. 100V (DC + peak AC)
    * Horizontal deflection
    o Timebase : 100ns ... 100ms/DIV
    * Triggering
    o Trigger mode : single automatic or free running
    o Slope : positive or negative
    o Level : adjustable in steps of ½ division
    o Trigger channel : channel 1 or channel 2
    * Digital storage
    * Resolution : 8 bit
    * Sampling rate : max. 32MHz
    * Memory size : 4kB/channel
    * Interpolation : linear or smoothed
    * Power supply : 9 - 12VDC / 0.8A
    * Dimensions (W x H x D) : 200 x 70 x 180mm
     
  9. tonykuphaldt

    Member

    Jan 10, 2004
    14
    0
    Sorry, I should have been more specific: there are many high-quality scopes that use a PC to display. It's just that a *sound card-based* osciloscope is horribly limited in features and functionality -- enough so that a beginner may very well be more confused than enlightened by trying to use it.
     
  10. jwheat

    New Member

    Sep 27, 2005
    7
    0
    I have been looking for a scope and discovered I can buy a good Tektronics 453 on eBay for less than a PC based unit. The advantage is a real, 50MHz scope with good triggering, AC or DC coupling, and probes to allow monitoring of higher voltage inputs.
     
  11. Johnwilliams

    New Member

    Oct 19, 2005
    1
    0
    For those who do go with the new pc based route id like to let everyone know that I bought mine from www.pc-oscilloscopes.com these guys seemed to have the best tech support around. for my application it was very worth the money. Much better than buying a used scope and not knowing how long it would last.

    Johnnie
     
  12. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Link Instruments has a nice pico oscilloscope.

    I've had mine for about 5 or so years now.
     
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