Sorry, Yogi

I used those coax inserts pretty successfully 20 or so years ago. The big difference was that I was using RG-188 and not hardline. With flexible coax, the connectors self-aligned great, but I suspect that the stiffness of hardline didn't permit that, leading to connector damage or displacement.

Cheers

Phil Hobbs

And those fancy mixed-function connectors cost an order or two of magnitude more than doing it simpler ways.

Well, they're cheaper than LEMOs. ;)

I did rather like having the coax connectors protected by the plastic body self-aligning. Blind mate coax connectors (e.g. Microdot) can be pretty vulnerable unless the mechanical tolerances are tight. What would you use in a VME cage instead of the mixed-function things?

Cheers

Phil Hobbs

Some of the multi-pin LEMOs cost kilobucks. My European customers love to specify LEMO connectors; can't imagine why.

Our VME modules (and our little timing boxes) generally use D-subs or SCSI 50/68 connectors for slow multi-pin i/o, or SMBs and SMAs for coax connections. We like SMBs because they are fast to mate and unmate. SMAs are for really fast stuff, or because a customer wants them.

Micro USB is a nice power connector, if you can run a box off 5 volts.

I've been meaning to look into FAKRA, which is basically protected SMB.

I wouldn't be brave enough to try blind-mating an SMB, though, so it would have to go on the front panel. Doesn't take too many manual mating-and-unmating cycles to equal the price of a $20 connector, let alone repairing squashed SMBs.

Interesting. I (ab)use a lot of HDMI cables, because you can't beat the signal integrity and versatility for the price. The two problems is that they tend to be quite stiff and heavy, and may vibrate loose if you don't clamp the cable. DVI connectors are more secure but larger, and may get harder to find with time.

Cheers

Phil Hobbs

yeh, and don't make the mistake of thinking that you can use DVI-I, i.e. dual link + analog, you can get connectors but cables don't exist

-Lasse

You can practically mate SMBs with your toes in the dark. To unmate, just yank on the cable. Beats looking for an SMA torque wrench.

Yeah, HDMI looks interesting for fast differential signals. I'll have to use them some day.

PCI Express cables are good but expensive.

But if you try using them on the backplane, the ~40 thou slop of the card in the guide will pretty much guarantee destruction. No?

Cheers

Phil Hobbs

That was pretty much my experience too. Semi-rigid coax probably would have been flexible enough to work, but what we actually used was "conformable cable" which replaces the copper tube outer of semi-rigid coax with solder-soaked braid.

And they make it several orders of magnitude more difficult for half-witted graduate students/technicians to connect the wrong coax cable to the wrong socket.

If you've got to fly a service engineer half-way around the world to correct this kind of mistake, good connectors pay for themselves rapidly.

VME backplane? That's defined, uses DIN connectors. We don't have coax connectors on that side of our modules.

Here's a VME...

Fakras are also keyed so they can be used for several incompatible functions on the same equipment. Auto companies love 'em. We use them by the box car load.

Like this one?

Or this one?

...or?

But you're right, they aren't as common as I would have thought.

IIUC VME uses Eurocard-style boards and connectors, so it's the same connector body outline as the ones with inserts that we were discussing, and the card cages are the same, so the mechanical tolerance issues are similar. The floating coax connectors make the mating very reliable.

Cheers

Phil Hobbs

er

Is marijuana legal where you are? It's a dandy mood-improver.

(Rich Grise isn't here any more, so somebody has to do the pot jokes.)

So it's 100% connectors, and the other half is thermal?

the

Except for metal boxes that also handle the shielding and/or ground retur n. And except for touchscreens. And except for IR windows. There are other exceptions, but I have a life.

al

he

Connectors indeed need mechanical support if for no other reason, to prov ide strain relief when the (ab)user connects/disconnects them. What else ar e you going to support them with, the board/chassis? Suppose there isn't on e?

That's nice when you have that option, but mass-market branded products o ften start with the packaging- form factor, material, color, dimensions, an d all- and connectors are more and more often custom-made to fit. Some are apparently deliberately designed so the user can't use it for anything othe r than the manufacturer's intended use. And you often don't even get to spe cify spacing from other connectors.

Have you examined a recent smartphone lately?

In industry it's worse- there are many generations of connectors in commo n use where I work. We have one machine with a WWII-vintage cannon plug nex t to a (recently installed, to interface with a newer temperature controlle r) USB socket.

Then there's military gear. Oh, and the scientific equipment you find in educational institutions.

I haven't actually *seen* a Fahnestock clip mounted next to an optical fi ber jack yet, but somebody's probably considered it if not done it.

t it

In your "dialect", are transducer (windows) part of the package or are th ey connectors? How about human interfaces- manual controls like knobs & but tons, touch devices, visual displays, speaker/mike grilles...?

What do you call those flexy bits of some packages (cellphones, some vide o devices and music players, etc.) that *are* the buttons?

hey

Then rating connectors isn't part of his job, is it? It does save him fro m having to (re)design *all* of their stuff.

It would be nice if we could all choose what we think is the ideal connec tor for a given application. I have never even visited that world, much les s lived in it, except occasionally when doing hobby "work".

I don't think you've done a lot of package design, from what you've said. Hell, we haven't even gotten into heat sinks/vents (where "packaging" meet s "thermal"). Or waterproofing. Or dustproofing. Explosion-safety, anyone?

Mark L. Fergerson

e:

ther

I tried it once or twice when young, and found that the main effect was as next day soporific, which is not an effect I need.

Thermal is something you can worry about after you have got the connectors right.

s the

urn.

None too well. Buried ground and power planes do those jobs a lot better.

xceptions, but I have a life.

If you had, you wouldn't be wasting your time here.

ical

the

ovide strain relief when the (ab)user connects/disconnects them. What else are you going to support them with, the board/chassis? Suppose there isn't one?

Jim Williams built circuits by tacking together discrete devices by their leads - my friend in Edinburgh once built the electronics for a prototype c olour TV camera that way, then scrunched it down until it fitted into the h ousing available. It can be done, but not all that many people can do it.

em.

often start with the packaging- form factor, material, colour, dimensions, and all- and connectors are more and more often custom-made to fit.

The marketing department is prone to think that it can dictate how big a de vice can be. From engineering's point of view they were convinced that noth ing would sell if it wasn't half the price of the competition, half the siz e and twice as fast.

thing other than the manufacturer's intended use. And you often don't even get to specify spacing from other connectors.

But you can specify that a particular demand is impracticable.

Is a Samsung S4 new enough?

mon use where I work. We have one machine with a WWII-vintage cannon plug n ext to a (recently installed, to interface with a newer temperature control ler) USB socket.

I worked in process-control for a while ...

n educational institutions.

The last hold-out of the BNC connector.

fiber jack yet, but somebody's probably considered it if not done it.

er

but

they connectors? How about human interfaces- manual controls like knobs & b uttons, touch devices, visual displays, speaker/mike grilles...?

If it's no providing an electrical or fibre-optic connection, it's not a co nnector. Switches, knobs and touch devices are manual controls, displays ar e displays and speaker/mike grilles are part of the packaging.

deo devices and music players, etc.) that *are* the buttons?

Manual controls.

st

they

rom having to (re)design *all* of their stuff.

But makes the design of his stuff rather simpler, though its performance ma y suffer in consequence. He does seem to be more into putting together besp oke electronics for people who can't or won't design their own than into de signing stuff that's state of the art.

ector for a given application. I have never even visited that world, much l ess lived in it, except occasionally when doing hobby "work".

Ground-breaking design work is tricky, but you can be less constrained by h istory.

d. Hell, we haven't even gotten into heat sinks/vents (where "packaging" me ets "thermal"). Or waterproofing. Or dustproofing. Explosion-safety, anyone ?

I do know what "intrinsically safe" is - from my process control days - and one of the units I've worked on ended up using heat pipes to connect the s tuff that needed cooling (the exhaust side of a Peltier) to a big blown hea t sink. Mostly we just stuck heat sinks on the boards and made sure that th ere was an adequate air-flow through the rack.

Don't start debating Sloman. He doesn't.

John Larkin does have a problem processing the responses. If he'd paid more attention during his undergraduate lectures, he might now be able to do better.

Because of how the hardline was routed, it had a little slop up and down, but not much side-to-side. Of course, the card guides tended to misalign the card connectors in the side-to-side direction.

In version 2, the EE guys eliminated the need for those co-ax connectors completely, by combining two cards into one.

Matt Roberds