There is described a system comprising mechanical equipment and an apparatus for monitoring and/or controlling the mechanical equipment. The mechanical equipment vibrates at a frequency fvibration in use, and the apparatus is attached to the mechanical equipment such that the apparatus also vibrates when the mechanical equipment is in use. The apparatus comprises an electronics module and a resonant electric generator. The resonant electric generator has a resonant frequency f0 comparable to the vibrational frequency fvibration of the mechanical equipment. The resonant electric generator comprises a magnet having an associated a magnetic field, a coil electrically coupled to the electronics module, and a resilient member. The resilient member is configured, when the apparatus is vibrated at or around the resonant frequency f0, to cause relative oscillation of the coil and the magnet so as to induce an electric current in the coil to thereby power the electronics module.
The present application also relates to the apparatus for monitoring and/or controlling the mechanical equipment, and to a method of use of the apparatus with mechanical equipment.