According to the design principle of magnetic sensors, they can be divided into two major types: contact (reed switch) and non-contact (electronic solid state).

Contact (reed switch Reed) magnetic switch principle is, through the reed switch within the two reeds, inducted into the magnetic field magnetisation and mutual attraction, and then mechanical contact conduction circuit, and send out electronic signals; and when the magnetic field strength is weakened, lower than the strength of the reed to keep the reed suction, then the two reeds popped open, the switch is disconnected. Advantage is able to adapt to a wide range of voltage, withstand voltage to 240 volts, and can be applied to AC / DC; disadvantage is that the reed switch's glass is thin and fragile, the slightest collision will make the sensitivity of the variation, the switch is also a result of the failure of the stability of the poor.

Non-contact magnetic switch is composed of electronic components, the principle is to detect the position of the magnetic ring in the cylinder through the characteristics of the special magnetoresistive IC, and output drive and switching signals. Compared with the reed type, electronic magnetic switch has the advantages of higher sensing accuracy, no false operation, vibration resistance, shock resistance and long service life, etc.; its disadvantage is the lower voltage tolerance, most of the non-contact switch can only be applied to DC 30 volts.