[Glen Akins] experienced a WW2-era aircraft engine cowl flap indicator lying about (as you do) and considered it would make a jolly good USB-connected indicator. The product in dilemma is a Basic Electrical design 8DJ4PBV DC Selsyn, which was meant for 4-engined aircraft. For these not familiar with the goal [Glen] explains in his in depth writeup, that piston-engine plane of that period were being air-cooled, and all through circumstances of utmost engine electrical power — these kinds of as during choose-off — flaps on the facet of the engine cowling could be opened to admit added cooling airflow. These indicator dials ended up linked to a sender device on each of the flap actuators, delivering the pilots an sign of the flaps’ positions.
The method of operation in the DC electrical power environment of WW2-era aircraft utilised the strategy of variable magnetic discipline orientation. The sender is a potentiometer, sending a voltage down the wire among 24V and ground. The indicator unit has a pair of coils set at 120 levels all around a ring, with the coils wired in collection, and
To interface this detail to contemporary know-how, a personalized PCB was constructed leveraging the USB functionality of the PIC16F1459 microcontroller, that [Glen] was already familiar with. Four Microchip MCP31HV41-502 electronic potentiometers ended up pressed into services instantly driving the coils of the indicator models. That may seem like an odd if not viable way to drive such a thing, but [Glen] goes into some substantial concept and some modeling to figure out which gadgets would have sufficient margin, which is worth a examine for the unfamiliar. Immediately after little bit-banging the SPI relationship to the digipots (even while the PIC has hardware SPI) [Glen] goes on to describe how the USB endpoints function, ending off with a .Web application to drive it all.
We’ve found a great deal of hacks bringing retro hardware back again to life, connecting to fashionable computing. Here’s a job that goes the other way, building custom made aircraft instrumentation from modern day areas.
