The speed sensor is a sensor that converts the speed of a rotating object into an electrical output. The speed sensor is an indirect measuring device, which can be manufactured by mechanical, electrical, magnetic, optical and hybrid methods.

Low resistance speed sensor and high resistance speed sensor

The SZCB-01 series magneto-resistive speed sensor is a kind of sensor commonly used to measure the speed of rotating equipment. They can be divided into high resistance type and low resistance type.
The high resistance SZCB-01 series magneto-resistive speed sensor is a passive sensor, which does not need external power supply. They use the inherent magnetic induction power generation principle to work. When the equipment under test is rotating, the magnetic field line of the magnetic pole will pass through the magneto-resistance element of the sensor, which will produce the magnetic resistance change at both ends of the magneto-resistance element, resulting in the change of the magnetic flux, thus generating the induced electromotive force on the magneto-resistance element, and the output signal is proportional to the rotational speed.
The low-resistance SZCB-01 series magneto-resistive speed sensor is an active sensor that requires external power supply. This sensor uses the magneto-resistance effect to measure the rotational speed. Its magneto-resistance element is made of two magnetic materials, with a thin magneto-resistance layer sandwiched between them. When the equipment under test is rotating, the magneto-resistance layer of the magneto-resistive element will be affected by the rotating magnetic field, resulting in the change of the magneto-resistance value. The output signal is proportional to the rotational speed. Compared with the high-resistance magneto-resistive speed sensor, the low-resistance sensor has a larger output signal and better signal-to-noise ratio, but requires external power supply.

Difference between low-resistance speed sensor and high-resistance speed sensor

Low-resistance speed sensor and high-resistance speed sensor are two different types of magneto-resistance speed sensor. Their main difference lies in the internal circuit design and working mode.
The high resistance speed sensor is a passive sensor, which is composed of magnetic ring and coil. When the magnetic ring rotates, the magnetic resistance value will change through the magnetic resistance effect, which will cause the voltage change in the coil, and then measure the speed. Because it is a passive sensor, the voltage of the output signal is low, and a high-resistance input circuit is needed to amplify the signal.
Low-resistance speed sensor is also a kind of magneto-resistance speed sensor. Its basic principle is similar to that of high-resistance speed sensor. It also uses magneto-resistance effect to measure speed. The difference is that the internal circuit design of the low-resistance speed sensor is more complex and has a certain circuit amplification function, so it can directly output the signal of higher voltage without using the high-resistance input circuit.
Therefore, compared with the high resistance magneto-resistive speed sensor, the low resistance magneto-resistive speed sensor does not need to use the high resistance input circuit to amplify the signal, and the output signal is more stable and reliable. However, due to the complexity of its internal circuit, the cost is relatively high. The choice of speed sensor depends on the actual demand.

Active sensor and passive sensor

The sensor that converts non-electrical energy into electrical energy and only converts energy itself, but does not convert energy signal, is called active sensor. Also known as energy conversion sensor or transducer.
Passive sensor is a sensor that does not need external power supply and can obtain unlimited energy through external sources. Passive sensors, also known as energy-controlled sensors, are mainly composed of energy conversion elements, which do not require external power supply.

Difference between passive speed sensor and active speed sensor

The difference between passive speed sensor and active speed sensor lies in its power supply mode and output signal type.
Passive speed sensor does not need external power supply. It uses the principles of magneto-resistance, inductance, Hall effect, etc. to output signals by detecting the magnetic field changes of rotating targets, and usually outputs pulse signals. Passive speed sensors are suitable for some harsh environments, such as high temperature, high pressure, corrosion, etc. Because they do not need external power supply, they are more durable.
Active speed sensors need external power supply, and generally output voltage or current signals. Active sensors need external power supply, so they are relatively simple to use, and the signal quality is more stable than passive sensors. However, due to the need for power supply, it may not be durable in harsh environment.