Pressure Plate Project

[EzcurraRuiz]

Hi, I am starting a project for the first time and need a little help.

I am currently looking at making a pressure plate with a couple of parameters. Firstly I want to be able to put the weight on and have a switch to stop a light from turning on. But when the weight is removed the light will turn back on automatically. I know I need a force sensor and its a fairly simple circuit, but all the force sensors I've seen are for very lightweight projects. I only need to know if the weight is on or off, with no measurements. BUT the weight will be up to 250kgs! and I need the project to be as compact and small as possible . I am creating this for my school project so any help you guys can give me would be amazing!.

Thanks!

 

[duke37]

Use a strong spring with stops to limit the movement and use the movement to operate a microswitch. You do not say how sensitive it must be.

 

[EzcurraRuiz]

It doesn't need to be sensitive, just need to register a minimum of 50kg being lifted off. It's basically a vehicle pressure sensor, it just has to survive a maximum weight of 250kg.

 

[duke37]

Your main problem will be the mechanical design and build.
You could use an antique balance as used to weigh sacks of grain or coal.
You could consider the use of Bellvile washers as a spring which has a self-limiting movement. This could be quite small.