What are some good oscilloscopes? I am thinking of buing one (ebay, of course). I don't think i will need anything over 100mhz. More is better, though.

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Ok, i guess 100MHz is quite a bit...

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I really like the Fluke 199C we have at work. Portability is nice. The small Tektronix are ok too, but I always find myself using the Fluke more often.

 

Umm... maybe i should have mentioned my price range is a maximum of $150...

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I just got a Tektronix 2212 off ebay. Its only has a 60mhz bandwidth, but for me, right now, its fine. I can't remember now what I paid, but it was around 150, with 3 probes and manual.

About a month after I bought it, my dad came into a 100mhz HP scope for free figures, lol

What I would like to know, and maybe some of you can tell me, is what is the advantage of 100mhz over 60mhz or even 15mhz. What falls in that 60-100mhz range that is commonly measured? 100mhz is mighty fast, and to me is only usful in RF or computer processors. and 100mhz dosn't cover much RF past HF ham bands. And your not even talking 1 mhz there.

 

The Tecktronix 465 is a very good CRT dual channel scope. Make sure you get working probes (I say working because it is easy to blow a probe with RF/HV) and good scope probes can be pretty expensive on their own. You need an x10 and a x1 probe or a x1/10 combo and should have as many probes as your scope has channels. I don't think you'll get a LCD scope for under $150, but they are nice and compact.
Remember that a 10Mhz squarewave contains harmonics up to 100Mhz and beyond. A 10Mhz squarewave will look like a sinewave on a 10Mhz bandwidth scope.

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If you are doing anything digital with a PIC at frequencies like 20MHz then you will want 100MHz or more. A square wave has as its component frequencies at X (the base frequency), then at 3X, 5X, 7X, etc (the harmonics). It takes several of the harmonics for it to look like a decent square wave. So you'll want 100MHz minimum for say a 20MHz signal.

 

This is a HIGHLY pessimistic point of view!, the ONLY thing running at 20MHz on a PIC is the clock crystal, and there's no need whatsoever to see how square it is, it either runs or it doesn't, and the waveshape doesn't matter. I'm not even sure if it's supposed to be a squarewave?.

While a 100MHz+ scope would be nice, it's hardly essential, and is only needed in an incredibly small amount of cases - probably 0.1% or less?, for normal hobby use. A 20MHz scope will do almost everything you ever need, and a 20MHz double beam scope would be FAR, FAR more useful than a 100MHz single beam (assuming you could find a 100MHz single beam?).

But ANY scope is a lot better than no scope, don't get carried away chasing high performance you might never need.

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*shrug* I'm frequently doing things that require the bandwidth. 200ns nstruction cycles ar 5Mhz base frequency, so I'd want at least 25MHz scope, and I might be looking for things beyond that at times (looking at transition times of switching devices, for example). Or looking at the HF noise spectrum of switchers, or trying to find out why and where in the heck some circuit is oscillating. At my old job they had real scopes - 8GHz Agilent's IIRC. What I'd really like is an MSO with bus decoding ability. We had a tektronix dealer here a few weeks ago demo one and it was awesome.

Just my opinion though. I admit I am an equipment snob with a tendency towards overkill.

And nah, the crystal output is a sinewave with some small harmonics on top. I got curious one day and measured it.

 

Ok. I am really not sure what i need in a scope, so i am not sure what information to give. I am just going to use it on small digital circuits. Just looking at some waveforms. learn a bit about o-scopes.

So what would be the best bandwidth to get? 25MHz?


EDIT:

What does "double beam" or "dual Channel" mean? Does it mean that it can monitor 2 frequencys at a time? So, instead of just being one line on the display, there could be up to 2?

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Double Beam and two channel mean the same thing. It means you can use two probes and display the waveform for each at the same time. Say you were looking at a ICSP interface, you could have the clock on one channel and the data on another. Many applications.

Do not overlook the HP/Agilent scopes. They are less sought after then tech scopes but rock solid just the same.

Get as fast or as slow a scope as you can afford. But as Nigel said be sure to get a 2 channel unit.

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Yep, i see the importance of a 2 channel scope. I am surfin' ebay right now.


EDIT: What is a Digitizing Oscilloscope?

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Presumably it's a digital scope - this converts the signal with an ADC, and stores it in memory, so you can freeze and store one shot events.

As for the type of scope you need, consider it as you would a car!.

Speakerguy79's point is that you MUST have at least a Porsche 911 Turbo, because you can't do 170 miles per hour otherwise.

My point is you spend more time going to the shops, or sat in traffic, than on the race track!

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What kind of o-scope do you have, Nigel? If you don't mind me asking.

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A basic dual channel 200MHz digital scope is a Z28 Camaro at best, you can get those for 1-1.5k from a number of companies. I'm just one of those buy it once, buy it for life types.

That Tek MSO4000 I saw a few weeks ago starts qualifying as supercar territory. The memory storage and bus decoding was just awesome. It would make debugging I2C systems a joke.

Also, definitely get two channels. That is certainly more important than speed.