Frequently Asked Questions about Electromagnetic Detector

When MP series electromagnetic detectors are connected to tachometers, FV converters, etc., if noise interferes with the signal and causes unstable display, a capacitor may be added to the input signal receiving terminal to mitigate the noise. Adding a capacitor creates a low-pass filter, which effectively reduces high-frequency noise.

Malfunctions caused by noise superimposed on the signal are particularly noticeable when the signal is near zero, as shown in the diagram below. MP series electromagnetic detectors are especially susceptible to noise at low rotation speeds because the signal amplitude is small.

The voltage sensitivity of TM series tachometers and FV converters is 0.2Vrms (=0.56 Vp-p) for AC signals. The capacitor capacitance is selected based on the balance between the signal amplitude in the operating rotation range and the sensitivity of the equipment.

With MP series electromagnetic detectors, the signal amplitude changes depending on the rotation speed and mounting gap. Furthermore, considering the influence of stray capacitance in the signal line and the receiver-side circuitry, it is impossible to predict the exact amplitude characteristics. Capacitor adjustment is necessary while monitoring the signal with an oscilloscope or similar device.