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Which oscilloscope to buy?

  1. Jul 21, 2016 #1
    Hi all,

    I'm looking for an oscilloscope for hobby/diagnostic use. I'd like it to be useful for automotive and mains/power supply type stuff as well as battery-powered electronics. What would you recommend? It would have to be a used one as budget is tight.

    I've seen some simple 'build your own' kits on eBay, but these only go to 50V and seem a bit basic. Is there a better one of these about, or should I go for a CRT one?

  2. jcsd
  3. Jul 21, 2016 #2
    You usually choose and instrument based on what you want to do with it. In this case what type of signal do you want to measure. Main considerations are digital or analog signal size, frequency response, rise time, repetition rate, sample rate, trigger characteristics. For voltages higher than your instrument can handle you can get attenuation probes that will reduce the size of the signal to that which your scope can handle.
  4. Jul 22, 2016 #3
    I'm just strarting out with this, but automotive signals tend to be 0-5 or 0-12 V square wave, PWM signals. You can also measure alternator output and ripple to check for bad rectifiers etc.

    As for mains stuff, our supply is 230V AC RMS @ 50 Hz. Also useful would be the ability to probe the guts of switch mode power supplies, in the ?kHz range. Similarly, I have an IGBT-based inverter welder that may need troubleshooting.

    Battery powered stuff would fit into the above, I suppose. I'm building an electric fencing energiser based on a 555 timer so again a 0-12v square wave and duty cycle measurement would be needed.

    Does this help?
  5. Jul 22, 2016 #4
    I don't know your budget. but for about $100 - $200 there are some off the shelf items. I suppose if I where looking for a scope I would try a pocket scope like a DSO Nano or the one that uses a PC or laptop something like a PicoScope2000 . The pocket scope may not be too good for fast switching signals and is only one channel and is probably useful for frequencies to 100 KHz while the basic PC scope has two channel and might be useful to 10 MHz. Two channels would allow you to compare two signals and a higher frequency response and would be better for fast switching signals. There are some positive reviews for the DSO Nano on the web with some seeing it useful for automotive work.
  6. Jul 22, 2016 #5
    Many thanks for your replies. I've found a used Hameg HM 203-5 dual trace scope. Not exactly perfect for my purposes but not a bad deal for £30. Since it's a bit bulky for automotive use I'll see if there's a UK supplier for the DSO Nano you mention. There's room in the budget for a portable scope still! I'll soon have a collection...
  7. Jul 22, 2016 #6
    It's size is that of the usual scopes that service techs were carrying around. 20 years ago. Try it out it may be what you need. You can easily put it on the fender of your car.
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