another board

a reference to a source of medical info that's fairly hopeless on anything outside mainstream. Plonk time wasting troll slowman.

NT seems to be totally unaware that the apricot kernel scam is old, and well known. As it usually does, wikipedia presents the story that I've know about for many years neatly and briefly.

NT prefers his dangerous delusions - which is not uncharacteristic of the less useful twits who persist in posting here.

As if I could care less. NT will keep posting nonsense, and I'll keep on posting comments - at least about the more flagrant and potentially dangerous nonsense.

He won't read the comments (unless they get embedded in somebody else post) and he won't have to put up with suggestions from me that he's a gullible twit.

He's never going to recognise that he's a gullible twit - so making the observation *is* a waste of time, as far as it's effect on him goes.

mal

he

Nobody else will ask, so I will.

How exactly is the board to be mounted? If the side you're calling the "t op" is the literal top, how does cooling air get from bottom to top?

If it's just typical designerese for "what I was going to call the 'compo nent side' until I had to put some on the 'wiring side' too" and the board will actually be vertically mounted (as seems obvious, but as I said, I hav e to ask), how many watts of heat, worst case, will the "topmost" component s have to handle, even given your tricksy dissipation-limiting software?

Other than that little worry, nice layout.

Mark L. Fergerson

Notches are routed in the sides of the board to let air flow from the bottom of the box to the top. You can see them in the photo, but I admit you have to be pointed at them; contrast is low.

I'd like to output 2 watts per channel, but without the software protections and cooling a shorted output could fry a transformer.

It mounts in a box like this:

There are lots of parts on both sides, so we called the side that goes up "top."

The other hazard is that the customer can short all the channels and cave in the wall-wart and crash everything. I have a big cap in the power supply to provide enough milliseconds of storage to keep the uP and FPGA alive until the software shutdowns kick in.

We generally call the side the PTH and heavy SMT parts the "top", no matter how it's oriented in the final product.

Sychros and resolvers? I work in aviation and those are rarely used anymor e. Even most of the aircraft where they were used have had avionics upgrad es and have gone to ARINC-429. (Not referring to low end private aircraft- that is not our market and I imagine not yours either) Is this an aviation application or another application where synchros are used?

You *told* me the board wasn't masked and I mistook the blue for some sort of masking/"don't touch" marking.

(sigh)

OTOH I can see the blue is box liner, now that I finally got my cataracts fixed.

(I can see the stars with my naked eyes for the first time in my life! Joy!)

Ah.

Yes. Customer-proofing is always the hardest part of design work.

I'm assuming the usual zener/tranzorb/whatever I/O protections won't work because the signals are too fast/high amplitude?

Not a lot of room on the board for that kind of thing either, come to think of it.

Mark L. Fergerson

Of course the board is masked. What I said was that the vias aren't solder masked.

All our boards are masked blue, with yellow silkscreen. Looks nice.

Blue anodize.

I got one lens replaced, and basically everything went wrong: tear, retinal detatch, vitrectomy, secondary cataract. That's finally all fixed, so I guess I'll do the other one soon.

It's amazing how much repair work a good doctor can do on an eye.

The most common i/o frequency will be 400 Hz, for synchros and resolvers. LVDTs can run in the KHz range. The real protection that we need is from shorted loads.

I have a polyfuse and a transzorb on the 24 volt wall-wart supply connector.