The first Instrument – Altimeter

Another thing on my todo list for the sim are fully working analogue instruments.If it’s not possible to work in the shop I’m using the time in the livingroom to create things in FreeCAD or build some electronics.
A perfect example for this situation is the creation of the analogue instruments: 3D printed housing, controlled by an Arduino – two things that can easily be done on the desktop.
So I started to design the altimeter in FreeCAD, make the electronics side working and also to program the firmware for the Arduino.

First step is always a CAD model:

After the first design I printed the parts and put it together with my real faceplate and glass – fits! 🙂

  • Everything will be controlled by an Arduino Nano, which also will controll the ASI, AOA, VVI and Markerbeaconlight
  • The needle is driven by an X27.168 stepper motor by a 1:2 gearing mechanism
  • Hundreds/Thousands/Tenthousands and the barosettings are done by 7-segment displays controlled by a MAX7219 LED controller chip
  • The PNEU-flag is controlled by a servo motor

After the first fitting test was positive, I continued working on the CAD model and now the whole mechanism is done, except the connector between the PNEU-shaft and the servo.

I’m still waiting for the displays for the barosettings, but everything works perfectly together with Falcon BMS

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