Reed sensors require no added circuitry; once activated they will directly switch the circuit or load that is needing actuation. Hall sensors need additional circuitry to carry out a switching function. They require a means of electronically amplifying the small voltage signal that is generated by the magnetic field. Once it’s amplified, it can then be used to turn on a power semiconductor device, which then carries out the switching operation. Electromechanical sensors require no added circuitry; once activated they will directly switch the circuit or load that is needing actuation.