Perhaps one of the bigger challenges in using older avionics is that most of them are deeply rooted in analog technology. More precisely, many avionics instruments form the 70s and 80s extensively use synchros and resolvers. Here is a picture of what a typical set of synchros in an instrument from the early 70s looks like:
Synchros are actually pretty old technology but are super resilient to noise and other external factors. They are still pretty common on just about all aircraft today, however, digital avionics have pretty much pushed them out of the cockpit. However, for the L-1011 sim project I will need a lot of synchro input to drive the avionics with. The good thing is that there are quite a lot of digital to synchro converters out in the surplus market that can be used for testing. The ultimate goal, of course, is to build some basic converters.
Below is a short video of my reference Digital to Syncrho converter. It's made by Shadin and actually designed to drive DME indicators ... however, it can be bent to control just about any synchro. It takes ARINC 429 data packets on one side and outputs an X, Y, Z synchro signal on the other side. What you see in the video is Label 251 data from 0 to 360". The really tall wave (enlarged by a factor of 2x) is the reference wave, I use it to trigger the scope with. The two small waves show the phase shift on the X and Y phase:
Synchros are actually pretty old technology but are super resilient to noise and other external factors. They are still pretty common on just about all aircraft today, however, digital avionics have pretty much pushed them out of the cockpit. However, for the L-1011 sim project I will need a lot of synchro input to drive the avionics with. The good thing is that there are quite a lot of digital to synchro converters out in the surplus market that can be used for testing. The ultimate goal, of course, is to build some basic converters.
Below is a short video of my reference Digital to Syncrho converter. It's made by Shadin and actually designed to drive DME indicators ... however, it can be bent to control just about any synchro. It takes ARINC 429 data packets on one side and outputs an X, Y, Z synchro signal on the other side. What you see in the video is Label 251 data from 0 to 360". The really tall wave (enlarged by a factor of 2x) is the reference wave, I use it to trigger the scope with. The two small waves show the phase shift on the X and Y phase:
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