To convert an old cockpit instrument into a clock, one can create a circuit that imitates the experience of being in the air. This process of transforming a King KI 266 DME into a clock was quite challenging, given that working with avionics is usually complex. The DME, also known as Distance Measuring Equipment, is a component of the radio navigation system commonly found in aircraft. It determines the line-of-sight distance from a plane to a ground station by calculating the time it takes for a signal to return after the plane sends out an inquiry. This plane-mounted equipment consists of a UHF transceiver and a display for the cockpit instrument panel, which receives an analog voltage signal from the transceiver and converts it into a readout on the Panaplex digital display.
Rather than making significant modifications to the instrument and directly controlling the display, [porkfreezer] opted to design a circuit that generates the necessary signals for the DME. The board, equipped with a PIC16 and an MCP47C dual 10-bit digital-to-analog converter, generates the required voltages, while a USB-powered DC-DC converter provides the ±15 volt supply needed for the DME display.
The entire assembly conveniently fits on a PCB at the back of the instrument. However, due to the high cost of the connector required to match up with the one on the instrument, the board had to be soldered directly to the DME’s pins. Nevertheless, this is an intriguing reuse of an unconventional piece of equipment, while endeavoring to retain the original design as much as possible. This approach is certainly praiseworthy.
Image Source: VladyslaV Travel photo @ShutterStock
