Oscilloscopes For Modern Engineers? 337
Every few years someone asks this community for advice on oscilloscopes. Reader dawning writes "I've just graduated with a degree in Computer Engineering (and did a Comp Sci one while I was at it) and I'm finding myself woefully under-equipped to do some great hardware projects. I'm in major need of a good oscilloscope. I'm willing to put down $2,000 for a decent one, but there are several options and they all seem so archaic and limited. I'm happy to use something that must be controlled through a PC if that gives me more measuring features. What would you, my esteemed Slashdot colleagues, get for yourself?"
dumpster diving (Score:2, Insightful)
Tek 1012B (Score:4, Insightful)
I'm rather fond of the low-end Tek scopes. The LCD screen is a little slow, and there's only 2 channels, but these are not huge limitations for most basic work. I use these teaching physics and intro electronics to undergraduates - they're easy to use, lightweight, and can store data through USB or pen drives. 100 MHz for about $1200, which is OK for general use.
cheap old used analog and some storage digital (Score:1, Insightful)
you need two. you do.
some old analog one, 10 or 50mhz should be cheap and easy.
then some digital storage scope with pc interface. I have a semi-cheap BK 2532 that is a low end but affordable unit for home use. (noisy fan, though).
tektronics is great but at the low end (your range) they all kind of suck. they do! that's why you need analog to 'see' the wave you can't quite see on those cheap a/d converters that $2k and less buys you.
ie, don't expect much from cheap digital on analog wave viewing.
plan to get 1 of each.
Ebay (Score:4, Insightful)
Scopemeter 199C (Score:3, Insightful)
My take (Score:5, Insightful)
Don't skimp. Get a good one, name brand (Tek, Agilent, LeCroy, etc.) at least 100 MHz bandwidth (the higher the better), 4 channels if you can afford it, some way to get data off the scope and onto a USB drive/network. Everything else is fluff and you can pay for it if you want, but I'd say the above are non-negotiable.
Don't even think about a PC-based scope. A scope is a standalone instrument, always has been, always will be.
Re:My take (Score:3, Insightful)
I disagree about "Don't skimp". I've got a 100MHz 2-channel scope from Owon in China, and it is great. Only set me back $300. I could buy ten of them for the price of a single Tek. I also have an old analog Tek but it never gets used.
After almost forty years in the business (Score:4, Insightful)
An employer. Seriously. Every piece of test equipment I've ever owned (some costing upwards of $5000 1978 dollars) was a lousy investment.
Especially when you consider that I have a lab at $WORK with scores of tools costing more than I make in a year, it's stupid to spend my own money on them.
Re:My take (Score:1, Insightful)
"Don't even think about a PC-based scope. A scope is a standalone instrument, always has been, always will be."
I hate to break it to you but most scopes already are PC-based.
Re:Buy a cheap digital scope and a good analog sco (Score:4, Insightful)
Before plunking down good $$, I'd wait and see what sort of equipment is *really* needed. Scopes are a nice tool, but there are other tools like good spectrum analyzers (with waveform analysers) and other gear that can add up quickly. I'd say, let the need present itself, then invest to the need.
Re:What do you need it for? Frequency range (Score:3, Insightful)
Not just funny, also correct. What is your application?
Digital or analog?
What speed signals?
how many channels?
Do you need any fancy triggering (often needed for digital)?
Are you using to for data acquisition or to debug circuits?
I'm not trying to make this tough, but the more you know about your application the better you can do at buying what you need and not a lot more.
Re:An old Tektronix is fine for a modern engineer (Score:5, Insightful)
Ah, but you are likely working as an electrical engineer. This fine young man will most likely get a job in IT. My suggestion to him is to hold off on the hobby scope for a couple years. By that time, his soul should be crushed sufficiently that he gives up on ambition entirely and has no need for the device.
Re:dumpster diving (Score:5, Insightful)
What lab will reject an instrument "due to it being fixed"?!
You used a 10% resistor that seems "close enough" the original was 1%. The calibration lab is used to making "minor tweaks" but having to twist all those trimmers practically all the way is going to take forever and piss them off. On the other hand, in Moms Basement, watching a Star Trek movie marathon while calibrating a scope is considered fun, not a waste of time.
You used inductive metal film resistor which screws up the high frequency performance instead of the specified non-inductive carbon comp resistor. It'll never work above 90 MHz again. The calibration lab will throw a fit because it won't calibrate at 100 MHz. However in Moms Basement you are thrilled to own a "90 MHz scope" even if the front panel label claims its a 100 MHz scope, especially since the highest clock frequency you'll likely subject the thing to anyway is probably low double digits.
You used the totally wrong temperature comp capacitors, and trimmed the rest of the scope so it'll work fine at 70 F. Unfortunately the industrial specs say it has to be calibrated from 32 F to 125 F so it simply can't pass calibration. The calibration lab will throw a fit, although it works fine in Mom's temperature controlled Basement.
That's before you start trying to mix old Tektronix scope silver bearing solders with traditional Pb/Sn and with modern lead free. I understand old fashioned Pb/Sn solder will corrode the plating off the Tek silver solder ceramic things.
Re:It depends on what you're designing. (Score:4, Insightful)
- If you're doing higher speed analog, lower-frequency RF or switching power supply design, I'm a huge fan of the Tektronix DPO series. I use a TDS3032.
If you're doing RF you're going to want a spectrum analyzer sooner rather than later.
If you're doing low freq / high power discrete analog (aka SMPS) you're going to want a curve tracer sooner or later, to fool around with if nothing else.
The original article poster has it all wrong, in that a lab that has nothing but an empty desk and a $2K scope simply can't handle the jobs that are easy in a lab with a $500 spectrum analyzer, $250 scope, $750 worth of Hakko (de-)soldering gear, a universal eprom/uC programmer, a logic analyzer, maybe a low end HP protocol analyzer... etc. Don't forget the "obvious" material handling equipment like $500 worth of lights on arms, magnifying glass on arm, low power binoc microscope, ESD protection gear, etc.