You don’t want to use this stuff in any new design. It is decades past obsolete. Use nice 7-segment LEDs. The only drawback is that the nice SMT ones (we use We are using DSM7UA30101) are all common-anode (unusual) and not many driver chips do that. We use an STLED316S driver chip. The data sheet is crap and it takes a while to get the software working though.
And if you are repairing old avionics, try to do a LED replacement board. If you are based in a certification regime where this can be done off the books, that’s the way to go. Then you can sell the board to others.
Peter wrote:
And if you are repairing old avionics
Peter wrote:
I am surprised the former USSR didn’t grab the opportunity to make these displays – they are good at making vacuum technology and are really printing money making valves like the KT88 etc for the western hi-fi market
I have a box full of Soviet made nixie tubes (or maybe just post-Soviet) date stamped 1991. Nixie tubes were obsolete in the west by the mid 1960s I think, but with the old Soviet system the factory probably just kept making them till someone told them to stop (or the USSR finally collapsed). They are good tubes, they have a small amount of mercury added so they last hundreds of thousands of hours even continuously illuminated.
AOA sensor teardown
Some of you may be aware of AvE. His videos are pretty entertaining on home workshop and general engineering discussions.
One of his viewers sent him a scrap AOA sensor from a herc. Interesting and entertaining. His surprise about the content of some of the internal components of “aviation grade” electronics may be familiar.
Inside an Ameri-King altitude encoder (AK-350). Date code on the ICL7109 ADC looks like 1998, week 40.
Construction (2 layer PCB, all through hole) seems similar to early 80s microcomputers like the Sinclair Spectrum.
Inside a Garmin GTX320 mode C transponder of late 90s vintage (mechanical rotary knobs on the front)
Solder side of the 2 layer PCB:
Component side – most stuff is SMD apart from the large electrolytic caps.
Inside one of the screened boxes (the PCB traces are likely filters, once you start getting into the GHz range it becomes a practical way of making them)
Inside the screened box with the TCXO:
View of component side with the boxes open:
Nice.
The encoder probably uses the EPROM / PROM to convert the 7-segment data from the 7109 to gray code.
Don’t you just love RF stuff? Probably anybody who knows this today has a beard (I don’t mean a hipster one; they are mandatory now) and wears sandals
I posted the innards of the encoder previously but they are all the same inside; I reckon they all just ripped off each others’ designs.
Peter wrote:
Don’t you just love RF stuff? Probably anybody who knows this today has a beard (I don’t mean a hipster one; they are mandatory now) and wears sandals
Or is Chinese. Don’t underestimate them – see some of the teardowns of things like spectrum analyzers that are coming from China now (where low cost = around 3k, rather than 25k you’d expect to pay with something from Agilent)
Sure; they prob99 just copied the American stuff from the 1960s and 1970s. Fancy RF construction like that is very labour-intensive but they can do it for peanuts.
Agilent/HP have the problem that they can’t drop the price from 25k to 3k even if they could.
Well, there’s also that Huawei are the only manufacturer of 5G equipment that’s really 5G and outperform by orders of magnitude the stuff from Nokia, Ericsson etc. and that’s why there’s this controversy at the moment, because if you want to make a worthwhile 5G network there’s only one game in town for the stuff in the cellular towers, and why the UK government wants to set aside with as little fuss as possible any alleged security problems with Huawei. The Chinese are just three leagues ahead in terms of technical superiority with this stuff at the moment.
Many people closer to the subject would differ
One view is that their software is crap. If Huawei is anything like the “higher end Chinese” routers e.g. Draytek, they are full of bugs and back doors – in fact exactly what the GCHQ has reported. They leave “factory” passwords in, etc. For example the older Draytek routers whose port 443 had a password of “drayteker” and unchecking the “remote admin” box didn’t disable remote admin; the only solution was to forward port 443 to an internal IP on which nothing was (hopefully) listening A back door? More like a front door.
