Oscilloscope advice

[dern]

I want to learn more about electronics for my car project and have bought a book which takes me through the basics. However, it says that an oscilloscope is an essential bit of kit and I don't have one... can anyone give me a brief run down of what they do, what the differences between them are and the cheapest way I could pick up something that would do the job for me.

I've got an a-level in physics and an o-level in electronics but that was all a very very long time ago now. Things I'm interested in playing with are pulse counters for creating shift lights and that kind of thing but really need to work through the basics first.

Thanks,

Mark

[apache]

you use them to give visual representation of electrical properties, ie a line on a screen will display a straight line above a reference as DC and sine wave for AC, chopped, etc etc. You can measure frequency and amplitude, see the output from devices switching on and off.
Or you could buy a couple and build them into a dodgy sci fi set complete with an old ejection seat for the pilot

[dern]

Is the frequency that is frequently mentioned in the specs the maximum frequency of the waves I can display on the screen or is the maximum sample rate and the actual maximum frequency substantially lower?

Are the pc based ones any good?

Thanks,

Mark

[TheExcession]

[redacted]

[GreenV8S]

I bought a cheap PC scope that consists of parallel interface 'dongle' thing plus some software. It's crap compared to a proper scope, but a fraction of the cost and doesn't need mains.

[dilbert]

You can get some really nice clobber on e-bay.

I was looking at an HP (Agilent) storage scope a month or two back. IIRC it was 500Mhz analogue bandwith, and 200MHz sampling. I think it went for about three hundred quid.

[Pigeon]

dern said:

Is the frequency that is frequently mentioned in the specs the maximum frequency of the waves I can display on the screen or is the maximum sample rate and the actual maximum frequency substantially lower?

It is the bandwidth of the circuitry that connects the inputs to the tube - basically the highest frequency which the scope's electronics can handle without registering a voltage which is lower than what you're really getting. It may be that on a cheap scope you run into difficulties in reading the display before you actually hit the limits of the electronics.

dern said:

Are the pc based ones any good?

They're useful if you want to record or do any processing on the waveform data, but generally a "real" one is a better bet for general-purpose use. It's somewhat similar with analogue vs. digital scopes - if you don't need the extra facilities that a digital one makes possible, an analogue one is easier to use. Certainly early digital scopes could be a right pain in the arse when you're used to analogue ones, though they're better these days.

Publications like Electronics World have adverts for places that supply second hand test gear, tested and calibrated. My scope came from one of these - "Telford Electronics, Old Officers Mess, Hoo Farm, Humbers Lane, Horton, Telford, TF6 6DJ, tel. [phone], fax [phone]", says the label - as you can see it was a while ago but I'm pretty sure they're still going, and they were a helpful bunch.

[AtomicRex]

I got in trouble for playing with the 'Wave machine' whilst working at Toshiba. I set the scale so that the signal received actually used the entire screen.

Unfortunately it then broke, and everyone pointed and told me Id broken the 'Wave Machine' I was never forgiven!

All those years at School and Uni wasted!

[dern]

Thanks for all the great advice, I'll keep an eye on ebay for oscilloscopes and wave generators and bide my time.

All the best,

Mark