Re: OT: sound speed depends on frequency on mars

On Sun, 1 Sep 2024 20:37:29 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>
In the 1980's we had NIM-format boxes with binary-weighted-length cables
and cheap slide switches, and CAMAC modules with basically the same
cables, but with fancy miniature DPDT relays in metal TO-8 style
packages. Physicists would invariably mess up the relay contacts.
>
Jeroen Belleman

 
I was thinking of using the cute little $1 Fujitsu telecom relays,
which are good up to about 3 GHz.
 
https://www.dropbox.com/scl/fi/bvcnqnvb4euc7pqw7wzab/DSC06884.JPG?rlkey=q1op81z1bumkfxoq8d5mtzi91&raw=1
 
I don't know if anyone would buy a PoE switched delay line box, but it
would be fun. Isola has some pretty good PCB laminates that aren't
expensive like the exotic Rogers stuff.
 
I never did any NIM, but we did a bunch of CAMAC.  It was a strange
bus, 24 bits of open-drain read data and a separate 24 bits of write
data. Design by physicists!
 
But the geographical addressing was great. Too bad VME didn't do that.
 

>
The modules I mentioned had coiled-up coax inside. You can't
squeeze much delay into PCB traces. I've come to think of
32ns as a really long time...

A delay box could be a hybrid, some coiled-up coaxes and some PCB
wiggle traces.

>
I used to spend most of my time with CAMAC in the 1980s, but I
haven't touched it since more than 30 years. It was a weird and
wasteful bus system, but lots of physics experiments used it at
the time.
>
NIM was simple and stupid. Just a crate with sturdy power supply
connectors in the back, with +/-6, +/-12 and +/-24V supplies.
There was more, but no one ever used that. Crates with lots of
analog would always exceed the current available on the +/-12V,
and for I/O, you were on your own. Other than that, it was handy
because it was everywhere. It's still used at CERN, whereas CAMAC
has vanished. Simple is better.
>
Jeroen Belleman

We invented this for aerospace test

https://highlandtechnology.com/Category/MPS

but there's no reason it couldn't be a NIM/CAMAC sort of thing, given
the right modules.

PCI/PXI boards don't have the panel space, power, or cooling to do
serious stuff.