Right behind a decent handheld DMM, a scope is about the second piece of bench gear I recommend to anyone. Old used digital scopes are so darn cheap anymore (my TDS340A that I've had for 18 years can now be had for $250-400 on eBay), and they really help you visualize what's going on in the circuit. I'd give up just about every other piece of real lab gear I own to keep my scope, because the rest is either for specific past projects, or is just nicer to work with, but could be substituted with lesser quality gear. There's no substitute for a decent scope in my opinion, but I do a lot of pure analog or serial stuff where being able to capture and stare at a waveform can go a long way towards finding a problem. Plus, all that digital eventually gets down to the real world, where ugly analog problems eventually rear their head again (slew rate, parasitics, transmission line uglies, etc.)
I'd bet I have my scope fired up 80% of the time that I'm not strictly working on firmware, and probably 20-30% of the time that I'm just working on code.
My main bench gear:
- Tektronix TDS340A scope
- HP 33401 bench DMM
- A couple various portable DMMs - one Fluke 87V, a couple cheapo Chinese, and a couple super cheapo Harbor Freight
- Saleae Logic16 logic analyzer (awesome tool, by the way...)
- Four old Lambda LLS lab power supplies
- Old HP 3310B function generator
- For soldering, a Hakko 936 iron, modified toaster oven for reflowing, and a hot air rework station
- a pile of other strippers, crimpers, pliers, screwdrivers, tweezers, magnifiers, and assorted hand tools including my favorite Xcelite MS-545-J cutters
- USBtinyISP for programming AVRs, Picstart 2 for programming PICs
- Mendelmax 3d printer for printing out parts and prototypes
- And a pile of other stuff to make the work more pleasant - my dev PC, a beer fridge, a TV, a Blu-ray player, a mythtv frontend box, a laser printer, bins of electrical and mechanical parts, datasheets I use frequently, etc.
I like all of the stuff, and wouldn't trade any of it, though I keep thinking about one of those new Agilent DSOX2024 scopes. I probably won't, though - my old Tek does well enough, and it has a great deal of sentimental value for all the years and projects we've done together. The only thing I'd really like is waveform capture on something that wasn't a 3.5" floppy...