Looking to buy an oscilloscope

[WelshWonder]

Hi all,

After a short time on here and learning rapidly, I am ever finding the need and use for an oscilloscope to study waveforms of the pedals I am building and to debug pedals where there are problems. I've found these handheld one that I think are pretty good for the money,

http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=1270135
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=4283909
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=1056459

What do you guys think? Will they do the job? I read somewhere that a 2 channel O-Scope will inevitably come in handy when I become more advanced but I'm not sure if these ones are single or double channel.

[brett]

Hi
I used the one second on the list for a few years and found it very good.  They are single channel, which may eventually become a limitation.  On the other hand, they offer factities that some fancier scopes don't have, such as RMS, peak, average and dB voltage calculations, and trace "holding" and "sampling".

I bought mine on e-bay for about 2/3 of the new price, and sold it for about $10 less. (Bought and sold in as-new condition)
cheers

[GibsonGM]

Hey Welsh,  (my family is from Wales, about 150 years ago ;o)

A scope, like any other tool, can be useful & indispendsible - or sit there looking at you and collecting dust.  I make all kinds of stuff, and rarely use one.  That said, the times I really want a scope, I have to use a program called "Visual Analyzer 8" that I  got free on the web (search Google).  You input thru your soundcard (don't put DC into the input!).   If you haven't used a scope, I recommend trying this program out...it's pretty close to "real world", has many useful features, and will show you what you can and can't do with an Oscope.  It gets the job done for me, since I am not actually measuring phase angles, voltages can be "pretty close" for what I do, etc.   For a visual representation of things going on in a ckt, it works just fine for me.  Over time I've learned other ways of measuring parameters; simulation software does a lot more before something is even built, IMO.

Using a scope, you CAN see your wave, but you Can't hear it, which is the 'proof of the pudding' in my opinion.  Our DIY stuff is simple enough to not REQUIRE a scope.  They're like a luxury...

If you have extra $, the ones you're looking at seem pretty cool, with decent resolution (sampling speed).  I'm partial to a bench-top model with a CRT, myself, and would get one used if I bumped into one    But you could make 3 new pedals with the money you'd spend....

So I guess the reality of the oscilloscope is similar to what you choose for an input or output cap...it's a personal decision based on your needs, choices, preferences....if you are building complex things and you really need to see the waveform, or doing a lot with inductors and phase angles, one could be very useful.  Or you might sink those pounds into something that is a very impressive, neat gadget, but isn't too useful to you! Ah, decisions...   

[sfr]

I've been borrowing my Dad's scope - (well, until the horizontal stopped working again) originally to tweak the trims on the ADA flange, but then I got some ideas, and started measuring things, and then I started working on a trem, and having it there on the bench, I ran into all these things where it was incredibly useful - I think it's one of those thigns where you never really realize how useful it is until you have one sitting there ready to use.  Certainly, working with modulation pedals and LFOs, it turned out to be a godsend as I started tweaking things.  (Of course, I kept coming up with more and more ideas as a result, and now I can't stop adding knobs and switches to things I'm working on)

That said, I don't know what sort of specs you should be looking for, as I can barely use the darn thing (a lot of calls to my father about which knobs I'm supposed to be turning again) but I think if you're seriously into this stuff and you think you can afford it, you will find at least one "god how did I live without this" situation and plenty of times when it's a huge hand.  Particularly if you're looking to create your own things.  But if you're building from schematics and layouts already on the web, you can certainly get by without one.

Plus, it's just an absurd amount of fun actually *seeing* how you've destroyed the signal.

[brett]

Hi
a cool thing to do is to input the signal from the probe into both a scope and a Ruby amp, so you can see and hear the waveform.  Especially if you're messing with distortion, it can be interesting to both see and hear things when you tweak values.

I've used a PC scope, too, and it was fairly good.  They are certainly vailable at the right price (ie free) and might be a good tool for evaluating whether a fancier scope will be useful to you.
cheers

[puretube]

came across THIS scope-primer, yesterday;
maybe of interest...

[Ronsonic]

Don't overlook the bargain prices on used scopes these days. As more and more household and industrial / commercial gadgets run at higher and higher frequencies, manufacturers and repair shops are ditching 'scopes we couldn't dream of using for hobby purposes at dirt cheap prices. Good probes cost almost as much as used scopes now.

Ron

[Meanderthal]

 Bout 5 years ago I passed up buying a rather nice one for $25.00.  I thought I'd never need it; I'd been getting along fine without one, the occasional DIY electronic gizmo I built wasn't at the level of having a use for it. Or so I thought.
Now I kick myself every time I think about that. What can I say, I'm an idiot.

[MKB]

Actually a good triggered sweep calibrated scope has the potential to be the main tool on your bench, as it can measure DC volts as well as AC.  A scope and a signal generator will allow you to troubleshoot most problems in a pedal.  I never work on a pedal without having a scope nearby, can't get by without one.

Be sure to check at hamfests and swap meets for scopes as you can often find older CRT models there for cheap.

[R.G.]

All very good advice, especially about the older analog scopes. I was recently offered an HP portable dual trace 60MHz analog scope for ... $10. I didn't even haggle, just opened my wallet. Get yourself an older analog scope by HP, Tektronix, Hitachi, or others while the getting is good. You need dual trace, triggered sweep, 20MHz or better.

You need probes. Haggle hard to get probes free with the scope, because good probes are going to cost you $20 to $300 new. Get switchable 1:1 and 10:1 probes if you have a choice. And mark scope probes down on your list of "If I find them, I buy them."

For purely audio stuff, a PC soundcard scope program is better than nothing. It will guaranteed give you erroneous results if your signals have much over audio frequencies in them, but mostly you get away with it.

I just bought my first entirely new scope - a Picoscope USB scope. It was about $650, but it gives me dual traces, storage, high speed, 12 bit sampling and 20Ms/Sec. It plugs into a USB port and is powered from the port. The same outfit offers a 25Mhz standalone bench scope for $399 and a low-cost Picoscope USB scope good to 2MHz for $359.

If you're going to play with effects in more than a paint-by-the-numbers way, you need a scope of some kind. If you're limited in funds, get the soundcard programs and build some front end stuff to improve it. If you need more frequency than that, get an older analog scope and be very, very happy with the performance, even if you have to live with some oddities of some of the switches not working great. If you have to have really good performance, get a USB scope. If you're much more of a pro than I am or have much more money than I do, get a Tektronix DSO for about $3500.00.

[caress]

you can always buy old busted scopes for a wealth of parts, too!  i bought two old tektronix scopes that were not working for $30 and pulled out a ton of tubes, including some good-condition (on a tubetester) telefunken tubes (ecc83's, 12ay7's, etc), a lot of old ge transistors, fun knobs and pots and switches, etc, etc...definetly worth it.

[WelshWonder]

Thanks to everyone for their advice, now I may have made a bad move, but I just won this scope on ebay ----> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=009&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=190080669222&rd=1&rd=1

Are there any shortcomings with this device that will limit me when using on diy pedals?

[Ronsonic]

Other than the risk to your eyesight from trying to read it, it'll be fine.

The one really nice thing about eBay, is that even if you don't like it once you get it, you KNOW that there's someone willing to pay just about as much as you did for it. You'll certainly be able to learn on it and it won't take a lot of room.

Enjoy

Ron

[Paul Perry (Frostwave)]

Now is *DEFINITELY* the time to grab old analog scopes. And grab plenty, because while you might be able to get a big old scope in perfect shape for $50 (in the USA), you won't be able to find anyone to repair one under $xxx, even if the parts existed...
It's almost impossible to imagine a scope that wouldn't be good enough for general DIY pedal work.