NDJ series digital viscometer (NDJ-1S-5S-8S-9S) is an intelligent instrument employing 16-bit high performance single chip micro processing technology. Different with the old method of gear speed regulation, it uses stepping motor to ensure stable operation based on set-up program. Torsion sensor drives rotor rotating in a constant speed. When rotor encounters viscous resistance in the tested liquid, after detecting and processing, the viscosity of the tested liquid is shown on the screen.