Where can I buy an Oscilloscope locally?

Discussion in 'General Electronics Chat' started by davidGG, Sep 23, 2013.

  1. davidGG

    Thread Starter Member

    Dec 22, 2012
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    I am looking for a digital or analog oscilloscope to buy from a near by store.
    Does any one know of any stores that sell oscilloscopes (used or new)?
    I live in Southern California, United States, very close to Downtown Los Angeles if that helps.

    I understand I can easily buy one online but that option is out of the picture at the moment.

    I've checked Craigslist but they are all very old/have problems.

    Thanks.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Got a Fry's nearby
     
  3. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Good luck finding new oscilloscopes in stores. You're much better off ordering them directly from the manufacturer.
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    Check with businesses that lease/rent measurement equipment. They often have units for sale ranging from stuff they picked up and are just looking to make a quick profit on to units that they are willing to sell new and everything in between. I would imagine there would be many such places in the L.A. area.
     
  5. killivolt

    Active Member

    Jan 10, 2010
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    http://www.ebay.com/bhp/digital-oscilloscope

    I went to my friends TV repair shop, and visited another. It's not much time they will be getting out of the business.

    One is a bit younger and struggling. He said he hardly uses a scope nowadays. The other is just old enough to retire.

    I think you can find them at a good price.

    kv

    Edit: Listening to WBahn, maybe you can find them in your area?
     
  6. w2aew

    Member

    Jan 3, 2012
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    I believe there are several Fry's Electronics in your area.
     
  7. davidGG

    Thread Starter Member

    Dec 22, 2012
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    Thanks for the suggestions, I found a 150MHz scope at fry's by for a decent price (used).

    One last question, I have probes made for 40MHz, is it okay if I use them for my scope as long as my signal frequency is less then 40MHz?

    If it is okay, what will happen if I use a signal frequency higher then 40MHz?
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    In general, you don't want to use probes that are not intended for that make/model of scope. The compensation circuitry in the scope probe is matched pretty closely to the input impedance of the scope and the capacitance of scope channel inputs varies quite a bit.

    Having said that, IF you can get the scope probe to compensate properly then you should be okay (big IF) and you should then be okay as long as you don't exceed the bandwidth of the probe. If you do, you will get progressively more bogus measurements.
     
  9. davidGG

    Thread Starter Member

    Dec 22, 2012
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    Alright, so these are the specifications of my scope
    [​IMG]

    and these are the probes I have
    [​IMG]

    So I need to match 1M/15pf on the probe right?
    So when I look for a probe do I need to match the input resistance/capacitance or the compensation capacitance?

    What's the difference?
    And is there a website where I can type in the specifications of my probe and it will give me a list of possible probes?

    Thank you.


    Also when I look at many probe specifications, the 1X probe capacitance is very high and 10X is near 15pf. Does this mean only the 10X mode will be accurate? and the only probes I can find with 15pf are with 10M resistance, I can not find any 1M/15pf probes. This is confusing stuff.
     
    Last edited: Sep 24, 2013
  10. davidGG

    Thread Starter Member

    Dec 22, 2012
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    anybody :)?
     
  11. killivolt

    Active Member

    Jan 10, 2010
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    What you should do is get the Manual in a PDF if you can find it and download it. Look for the replacement part #, then go to the manufacture of the probes, to see if you can buy them.

    That way there will be no chance of getting the wrong probe.
     
  12. #12

    Expert

    Nov 30, 2010
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    1) Wrong.
    2) No.
    2a) They are all built like that. The compensation is not for the 'scope, it's for the probe.
    3) The probe will be accurate if the circuit you are measuring can deal with the resistance and the capacitance of the probe.
    4) The probe will be accurate to the frequency listed for the probe.

    You're over thinking this. If you aren't working on multi-megahertz circuits, there is nothing to worry about. If you WERE working on multi-megahertz circuits, you would already have some clues about the limitations.

    For instance, if an oscillator uses a 1 meg resistor or a 50pf capacitor, the 'scope probes are going to throw it way off. If you're looking for an accidental oscillation on a voltage regulator and all you see is fuzz, that's all you need to know...it's oscillating. If you're looking for the rate of rise of a gigahertz square wave on a computer board, you shouldn't be in there at all. It's way too fast for a 150 Mhz 'scope.

    Buy the best probe you can afford, up to the frequency limit of the 'scope. It's going to last until you are a lot more experienced, and your needs will only get more sophisticated. By then, you will know what 15 pf is going to do to the circuit you are measuring.
     
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