Oscilloscope

[Davey]

Looking for a very basic oscilloscope on e-bay, I see lots of Hantek devices. Are these any good/bad/indifferent?

[dom]

Old analogue scopes up to a few tens of MHz cost beans these days on ebay.

I bought a perfect Tektronix 2215 (60Mz) scope for £20. Cost more for som e new probes!

[newshound]

+1 (I paid a bit more for a Phillips storage scope)

[Dave Plowman (News)]

You need to be more specific. Is it just for workshop use where size and powering ain't an issue? Do you need to be able to capture the screen output easily?

It's just that older analogue scopes can be good value used. With a much better performance than a new digital one at anywhere near the same price.

[John Williamson]

As the OP has now told us that all he's doing is tracing some hum on an amplifier, this should do the job:-

He needs a computer with a soundcard, and a handful of passive components. Two resistors and maybe a transformer to stop earth loops

[dom]

Yes, there's quite a price premium for storage - I guess because even slow storage scopes are still somewhat useful in developing small microprocessor-based devices where all you need is to capture some transitions on GPIO etc.

Low MHz analogue scopes now seem pretty much confined to either analogue applications or signal tracing in repair work, I never see them in professional settings any more - not even as old dinosaurs in a dusty corner of the office.

[Davey]

That looks very interesting, thanks. I will consider it. The max. voltage will need care to reduce.

[Davey]

Yes, I let one get away. There seem to be plenty 'for parts'.

[Davey]

The output voltage of the amplifier's transformer is 40V, and if, as suggested in the FAQs for the software 'scope, a maximum input voltage of +/- 0.7V is true for the mic input, then some serious voltage dividing is required.

[newshound]

Reminds me of the three day week in a CEGB research lab where we found it was necessary to have one of the big trolley-mounted Tektronix jobs (100 MHz?) running in the office (hooked up to a circuit board to look as though it was doing something of course).

[Martin Brown]

Not necessarily since the inputs are AC coupled. And the signal path inside an amplifier tends to be around 2v RMS max apart from very close to the final output stage where larger voltage swings may be present.

8W into nominal 8 ohms is about 12v peak to peak sine wave.

A 10x scope probe should be adequate protection for it (unless it is a valve amplifier with silly voltages inside when all bets are off).

[John Williamson]

Still only two resistors, you just need to take the input impedance of the computer into consideration. If you're *really* a cheapskate, just stick a`100K ohm resistor and a 1 microfarad capacitor in series with the wandering lead, and another capacitor in the earth side of the connection. The voltages won't be accurate, and nor will the frequency response but if all you're doing is checking for a hum signal which may turn out to be on a power supply line, then the capacitor will isolate the DC and let through enough AC to check for hum on the line. A 240 to

12 volt stepdown transformer with a capacitor in series with the primary winding would be better than the resistor, but would cost a lot more and might give problems with loading on the circuit being tested.

[Scott M]

My 2p: I've got a DSO201 Nano which is a single channel storage 'scope built into the case of an MP3 player. Works very nicely, not expensive (£40) and doesn't take up a lot of space. I've learnt a lot from it, never having a 'scope of my own before. Can't remember if it was recommended here, but I read some reviews which feted it and I've been very pleased with it.

They is a more expensive 4ch one, the DSO203 for £100.

[Davey]

I've seen that name around, too. Like you, not having owned one, only used one occasionally under supervision or instruction, there is a lot to learn (the hard way). I have never been taught electronics, just learned what little I have while working at instrumentation setup in factories.

[Scott M]

I've got a bloody degree in electronic eng, but don't recall seeing a 'scope since school. I went into software rather than EE (having had electronics as a hobby since v young) and still have yet to leverage anything useful out of 3 years at Uni. It was all very theoretical with nothing practical to speak of and I suspect a lot of people leaving couldn't reconcile a circuit diagram symbol for a transistor with a small plastic package with three legs! What I'm saying, is don't worry about a lack of being taught it!

[Davey]

Thank you, I won't! If people will help me here, I will try to learn from them. I am not too proud to be afraid to ask a question which may seem obvious to others, but not to me, and I would rather be safe than sorry. I learned a lot from my years at Engineering University, and have been to many different parts of the world using that knowledge. But my course also included lots of practical periods, which might have made a significant difference.

[tony sayer]

Got a excellent Phillips/ Fluke 4 Chanel one from here 195 and it was in mint condition :)...

[tony sayer]

Yes sad but true a lot of peeps can't;(...

[Davey]

Interesting site, thanks.

[John F. Morse]

The October, 2013 issue of QST reviewed the Rigol DS1052E and Tektronix TBS1042 oscilloscopes.

The Rigol seems to have better specs, and also $350 cheaper. I would like to own one.

Don't know if you can access the Digital QST Edition without a membership, but the link is:

If that fails, visit a local library.