Digital Tachometer kit


Range: 100- 9000 revs per minute. 2 digit display


    • 2-digit LED display
    • Adjustable display brightness
    • Suitable for 2- and 4- stroke petrol engines
    • Configurable for engines of between 1 and 12 cylinders
    • Simple installation and calibration
    • Front panel included
    • Contact bounce suppression


    • Supply voltage. 10 to 15V DC, unstabilsed
    • (built-in regulator)
    • Supply current: 200mA (maximum)
    • Display range: 100 to 9,900rpm
    • Resolution: 100rpm
    • Display type: 2 x 0ᄋ5in., 7-segment LED (static)
    • Input sensitivity: 3V (minimum) 20V (maximum)
    • Input impedance: 30kW (typical))
    • PCB Dimensions: 80x45mm (3.2″x1.8″)+ 80 x 60mm (3.2″ x 2.4″))
    • Front Panel Dimensions: 70 x 90mm (2.8 x 3.5″)

The majority of modern cars, and practically all ‘high performance’ models, are equipped with a tachometer, or rev counter, which gives an indication of the number of revolutions per minute (rpm) that the engine’s crankshaft is turning at. This is a very useful instrument to have, since it enables the driver to maintain the engine turning at its most efficient rate for the maximum production of either power (BHP), or torque (the pulling force being exerted), factors which coincide with specific engine speeds (the values for which may be found in the vehicle handbook, or magazine road test reports). Hence, this can be used to give maximum acceleration, or optimum flexibility, particularly useful when climbing steep inclines or towing caravans, boats, etc. An additional use for a tachometer is as an aid to servicing, since it enables the engine idling speed to be set to the value specified by the manufacturer, in the event of it idling too fast or slow, as is often the case. However, many older, or ‘base-spec’ vehicles, are not equipped with a tachometer. This situation is easily rectified, by installing the digital version presented here, which is simple to fit, calibrate and use. Furthermore, by using a suitable sensor (ie. one that simulates the switching action of the contact breaker), the unit allows rpm measurement, or the number of movements per minute, of any rotating or moving mechanical part – it does not necessarily have to be an engine!