Extech 461893 Digital Photo/Optical Tachometer

four AA batteries and a carrying case. Model 87700-00 includes one convex tip, one flat tip, and one surface wheel. Model 87700-01 includes a 23" (58.4 cm) roll of reflective tape.

All tachometers are microprocessor based with limited memory capabilities. Memory stores the final reading, as well as the last minimum and maximum—recall readings at the touch of a button. Both the contact and optical tachometers feature a large, five-digit LCD.

Contact Tachometer
Use this digital contact model with either a concave or convex tip to measure the speed of rotating objects (rpm measurements). Use unit with the linear speed wheel to measure surface speeds (ft/min or m/min measurements). Tachometer automatically suppresses insignificant zeros to provide precise rpm readings.

Optical Tachometer
Use the digital optical model to take noncontact speed measurements of rotating objects (rpm measurements). Tachometer uses a reflective mark and an integral light beam to provide precise readings. Display updates once every second. Autoranging function switches between two ranges: 5 to 999.9 rpm or 1000 to 99,999 rpm for greater accuracy.