Avionics + mil-spec teardowns

Added photos and a high-level speculative analysis (not the normal detailed circuit-level analysis) about a mystery Martin-Marietta digital board.  It may be a string of shift registers for serializing/de-serializing data as part of the telemetry or radio-control system on a Titan rocket....or it may not.  It depends on a government contract number that I don't have info on.

Posted analysis of some old 70's mystery computer(?) cards from IBM Federal Systems Division, with nice gold hybrid modules, and an attempt to interpret the comparator(?) circuitry inside each hybrid:

https://www.eevblog.com/forum/projects/reverse-engineering-old-aerospacemilitary-computer-peripheral-boards/

I also have extra copies from the same batch for sale.

Added some analysis (2 out of 3 boards) for some Rocketdyne PCBs I picked up from an industrial surplus seller - really special stuff here, with lots of gold, hybrid-circuit modules, and heavy-duty construction.

Added photos of an Interpoint aerospace DC-DC module, along with an analysis including a high-level schematic.  Lots of interesting colorful parts inside, with multiple ceramic substrates.

Added analyses of the SINCGARS frequency synthesizer and transmit frequency modulator / up-converter ("exciter").  It's interesting seeing the different functional blocks broken out into visible components, vs. using an all-in-one modern commercial approach that does most of it on one or two chips (not that the die photography on those isn't great in its own right!).

Added photos and some descriptions of SSI (small-scale integration; logic-gate-level) IC-based computers from the 70's; both the AN/UYK-7 standard Navy computer, and a Marconi-Elliott board from an aircraft navigation computer or system.  It's fun to see the amount of logic in a CPU split out into so many individual parts, along with the old insect-looking flatpack IC packages, and the winding hand-drawn traces.

Added BAE Systems Audio Signal Discriminator, whose circuitry is simple but whose workings are a total mystery to me.  Any insights or outside knowledge welcome here in decoding what this is supposed to do.

Added the Elliott Air Nautical Miles Indicator: this is one of the very occasional convenient devices where someone else (the Le Labo De Michel youtube channel) has already done the hard work of figuring out how it works!  The photos are mostly there for anyone wanting a better static, high-resolution view than can be done in a video.

Added an entry for the (existing) Raytheon UHF receiver writeup; made the title a bit more general as there's going to be more future material that falls outside the strict definition of aircraft electronics, but is similar in spirit.

Added the McDonnell Douglas Voice Warning Generator from an F-4; hoping to look inside the hybrids at some point.