LDM
This video shows the teardown of an encoding altimeter ARC EA-401A. The functioning is described in the US Patent 3,867,680 dated 02/18/1975
https://www.freepatentsonline.com/386...
The static air pressure is converted into a displacement using an aneroid capsule. The displacement is measured using a servo control mechanically linked to the pointer. The zero detector uses a bulb and two photo-cells. The linearity correction which is the topic of the patent mentioned above is performed using a baffle in the detector assembly. The baffle permits to modify the zero condition and therefore permits to change the altitude indication from a given static pressure. The position of the baffle is a function of the static air pressure. The baffle is positioned using a non-linear cam which can be adjusted in order to have the correct altitude indication from the static air pressure.
00:00 - Intro
01:10 - Short description of US patent 3,867,680
04:00 - Teardown
10:45 - Power up and Magic Smoke
11:30 - Servo control amplifier