USB hubs in the lab, any caveats?

My experience is that it's pretty much impossible to fry anything with USB; even cheap implementations do provide current limiting.

A non-powered hub will limit its "downstream" devices to 100mA each, in almost all cases (I've seen a few "hybrid" design where one port gets more current and the rest get very little, but it's uncommon); you'll want to check to make sure your various peripherals will work with that. (Anything with its own power supply generally will, of course, as will mice, keyboards, joysticks, and some webcams... anything else you just have to try it.)

I would make an effort to use decent quality cables -- some of the cheap ones seem to leak noticeably more, and I very much suspect the USB certification stickers on them are counterfeit.

I was playing with a receiver design last week that didn't want to work with low input signal levels, and the problem turned out to be that one of our newer Agilent network analyzers puts out a birdie at exactly 45MHz -- the same as one of my IFs. @#$#$%(@$

---Joel

Thanks, Joel. Ok then. I'll get a hub and just connect it all up. USB is amazing, no addresses to set or worry about, it just works. Usually. The only thing that sometimes doesn't are RS232-USB kludges. But to my surprise the new scope was the 2nd piece of gear that came with a RS232 that wasn't mentioned in the advertising. So if it all goes wrong I know I can still talk to it the old-fashioned way.

Yes, I buy brands like Belkin or Targus. The good stuff.

Another reason why I shunned the big mfgs for this new scope. My first encounter of this kind was also an Agilent analyzer. An EMC analyzer no less and one of the more expensive kind. There was a small stand of trees on the screen that remained stubborn. I was slowly beginning to worry whether I still had all my marbles, at least in terms of EMI fixing. Then I found the source: The screen of that very analyzer ....

The latest one was a TDS220 which sent so much conducted EMI into a new circuit that I got fooled into believing my PID loop was slightly unstable. I mean, it could happen. Finally I hooked up a real scope, a Tek 2465, back from when they built the good stuff. Bingo, the noise was gone. Turned out it also originated at the screen, probably the backlight inverter.