How much fuel in the tank! This question always bothered And the driver of the car, and the motorcyclist and the pilot of the glider. And if the car with varying degree of accuracy to this question can be answered, then the rider or pilot single-engine aircraft that is a lot harder.
Offer device for signaling on the minimum fuel remaining in the tank - based reed relay with contacts working on the circuit. As you know, when exposed to the permanent magnet on the reed switch contacts they are closed, and is used to horn switch and warning light.
The principle of operation of the indicator: 1 - fuel tank; 2 - tube, 3 - float with a permanent magnet, 4 - reed
The sensor of the detector is made of a glass or plastic tube, inside which can freely move the float attached to it a permanent magnet. The reed switch is mounted on the outside of the tube. Tube fixed directly in the fuel tank or installed outside, not far from it.
When the tank is full, the float is at the top of the tube and accordingly, the contacts of the reed switch open. As the generation of fuel float is lowered, and in a position corresponding to the minimum level fuel, the influence of the magnetic field makes actuate the reed switch contacts and the circuit is closed.
In principle, you can install multiple reed switches according to the height of the tube, and then to get more information about the availability of fuel in the tank.
Author: V. Maslyak