Hello, I have cool idea for a device and one hardest part of it is to detect the movement of the object. I think I can use a wire coil, and a small magnet attached to the moving object. When the object passes the wire coil (up or down), there will be small voltage inside the wire coil. It will be positive or negative voltage depending on the direction of the movement. When no movement, no voltage generated. This is my understanding so not sure it is correct or not :D Then, the wire coil is connected to a circuit board with few transistors on that, if positive voltage (object move up), led 1 turn on, if negative voltage (object move down), led 2 turn on. When no movement, no led on. I'm IT developer, physic and electronic are not my strong fields so I am seeking for help from you guys to confirm my knowledge and help in calculation, also the PCB design. I want to mass produce this device and may be we can be partner in future. Thanks a million !