Re: [AH] buying an oscilloscope (was [AH] Visual patterns from analogue

From bagofskin
Sent Sat, May 11th 2013, 23:09

Awesome advise. Thanks man!

Scott

On 2013-05-11, at 2:53 PM, "cheater00 ." <cheater00@gmail.com> wrote:

> The "vector rescanning" technique is not possible on DSOs because they
> alias waveforms. DSOs also suck for stuff like Lissajous patterns and
> in general x-y display. But unless you get a bistable analog storage
> oscilloscope like one of the Tektronix 7000 series bistable storage
> scopes that start at around $400 used you have to use a digital scope
> to see slow signals like CVs. Those are, however, well suited for
> analysis via line-in - just get an analogue volt meter with recorder
> output, select the right range, and take the output into your sound
> card.
>=20
> When buying any scope, make sure it can do XY mode, that it's at least
> dual trace, that it can subtract signals (A-B), and that it has
> 1Megohm inputs, not 50 Ohm ones.
>=20
> Try to go for scopes where the CRT uses at least 20 kV acceleration voltag=
e.
>=20
> When buying a scope from ebay, ask the seller if it has any burn-out
> (don't buy one where there's something burnt into the phosphorus, like
> on an old TV). Ask the seller to use the scope's callibrator (most
> scopes have one, if not ask him to use an external one). The
> callibrator is a square wave generator. Ask the seller to take a
> picture of the scope displaying an image of the calibration signal on
> each channel at once, such that the waveforms cover 80% of the
> screen's height. Make sure the square waves aren't lopsided or curvy,
> that there's no ripple, and that the traces aren't thick (a sign of
> noise).
>=20
> When buying in person, make sure to plug it in and see if it works,
> use the procedure above.
>=20
> Always ask if probes are included. It's a hassle to get extra probes.
>=20
> Once you get it, let it run for a couple days without shutting it off.
> Make the trace very dim (just barely visible) so that it doesn't burn
> anything in to the phosphorus, or even turn it down completely. See if
> it still works afterwards. Don't give out any ratings until you've
> done that.
>=20
> Learn what triggering is and check if it works. It's useful. A scope
> with external trigger is useful for displaying synth waveforms and how
> they react to filters etc, but only if you have a modular with a
> counter.
>=20
> Cheers,
> D.
>=20
> On Thu, May 9, 2013 at 1:54 PM, Thomas Strathmann <thomas@pdp7.org> wrote:=

>> On 08.05.13 21:31, Nicole Feeder wrote:
>>> I bought an oscilloscope a few years ago. I looked around a lot for a
>>> used one, but it was tricky for me to find something at the time. I
>>> ended up settling on a small, new digital scope - Rigol DS1052E 50MHz.
>>> I've been happy with it. It isn't quite as nice as some of the
>>> Tektronix's scopes I have used, nor as sensitive and whatnot as some
>>> analog scopes, but I was spoiled in the physics department for years.
>>> For under $400 it is a nice, reasonably sized scope that fits on my
>>> bench well and has good functionality.
>>=20
>> Seconded. I've got the 100MHz version which is basically the same
>> machine. Compared to other (often fancier) digital scopes in the same
>> price segment I'd say that the Rigol definitely feels sturdier and not
>> as wobbly in day to day use. Although it should be noted that there are
>> probably some DSOs that are quieter in operation. The fan in the Rigol
>> is not the best possible one (a small, high-speed, low-cost thing). All
>> in all I don't regret buying it and wouldn't go back to analog for most
>> measuring tasks I do.
>>=20
>>        Thomas