Tachometer is a device used for measuring the number of revolutions of an object in a given interval of time. Usually it is expressed in revolutions per minute or RPM. Earlier tachometers purely mechanical where the revolution is transferred to the tachometer through mechanical coupling (cable or shaft) , the rpm is determined using a gear mechanism and it is displayed on a dial. With the advent of modern electronics, the tachometers have changed a lot. This article is about a contactless digital tachometer using arduino. The speed of the motor can be also controlled using the same circuit. The RPM and all the other informations are displayed on a 16×2 LCD screen. The circuit diagram of the digital tachometer using arduino is shown below.

REQD. Components:


01) Arduino UNO or Simillar [x1]
02) USB Printer Cable for Arduino [x1]
03) Solderless Breadboard [x1]
04) 9V Battery [x1]
05) 9V Battery Clip for Arduino [x1]
06) DC Motor (4.5 VDC) + 0.1uF Capacitor [x1]
07) Rectifier Diode (1N4148) [x1]
08) npn Transistor (P2N2222A) [x1]
09) Resistance (220 Ohm) [Red-Red-Brown] [x1]
10) Character LCD Module (16*2) [x1]
11) Potentiometer (10 kOhm) [x2]
12) Jumper Wires