The BinMaster Vibrating Rod Level Sensors are piezoelectric devices with a single rod shape vibrating element. The rod of the sensor vibrates if there is no material covering the active rod. When the rod is covered with material, the vibration is dampened and the electronic circuit forces the relay to switch. When the rod becomes uncovered, the vibration will restart and the relay will switch back. The rod is fixed at two points in a way that it forms a perfect swinging system with very little mechanical losses. In action, the vibration is driven by a piezo system, which gets electrical pulses from the electronics. These electric pulses enlarge the size of the piezos which lead to a bowing of the rod. Since the pulses are exactly on the frequency where the rod is in resonance, the entire rod starts to swing. A second piezo system works as a swinging detector. If the piezo gets distorted, it gives a voltage signal to the electronics. This way, the electronics can check if the rod is vibrating or not.