Wiring Diagram RPM Gauge

RPM (round per minute) is a number that shows the number of turns of a system in 1 minute. Usually used as a pointer to engine rotation on a motorized vehicle, making it easier to regulate power and fuel. This measuring device is commonly called TACHOMETER.

In a 2-wheeled vehicle, engine speed can be obtained by calculating pulses on the armature, but this is difficult because it has to open the engine block. The easiest way is to use radiation from the CDI to the BUSI which can count the number of pulses. So by using the principle of electromagnetic radiation, enough to wrap copper / email / enamel / dynamo wires to the cable near the end of the spark plug cap, then a constant voltage (pulse) can be obtained. The number of turns is not important, just approximate until the voltage generated can activate the transistor as a counter switch.