80 mm diameter.
A turning magnet ratio measuring movement is the main component of the tachometer. It converts the current pulses from the sensor to an analogue display on a dial. An electronic circuit converts varying current pulses to unified pulses, which are fed to the turning magnet movement. The turning magnet ratio measuring movement applies the principle of the current ratio of two separate coils. Two stationary coils generate a magnetic field as a function of the current flowing through them. The magnetic field resulting from these two fields moves a two-pole magnet disc carrying a pointer. The pointer deflection is a function of the ratio of the two currents flowing through the coils.
A shielding casing prevents the effect of external magnetic fields.
The special electronic system controlling the movement permits a pointer deflection of 320
. The rotation is limited by a pin on the turning magnet moving in a groove of the coil carrier; the oposing force is generated by a spiral spring.