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A microcontroller based automobile digital RPM meter

Some of the smaller cars available today does not have an RPM meter on them – this would be some trouble since you wont be able to determine the actual speed of the car’s engine, thus will have an impact on the fuel consumption since engines are efficient at a certain range of shaft speed. This project makes use of an AVR microcontroller and a signal conditioning circuit that makes use of an LM324 operational amplifier (Op-Amp). The input signal was taken from the High Voltage (HV line) of the main distributor of the engine. This specific point was chosen since all (gasoline) engines have an HV line. The signal from the HV line is fed into the signal conditioning circuit before being fed to the microcontroller’s PB1 pin. The Timer/Counter1 External Counter Input mode of the PB1 pin is used as an external clocking source for the MCU’s timer1 making it able to do frequency measurements. While another timer (timer0) is used to measure the elapsed time. If you wonder whats in the HV line that makes it a good… Continue reading

PIC based Digital RPM counter

Digital RPM Counter

Digital Tachometer or RPM (Revolutions Per Minute) counter is a tool telling the speed of some object rotation. In real world tachometers often can be fount in most cars panels. RPM indicates rotation of engines crankshaft. It usually gives some information to drivers on throttle and gear usage. So PyroElectro have built a digital RPM counter that can be used for most setups like fan motors or other spinning parts. It is based on optical detector where infrared diode is directed to receiver and moving object interrupts signal at some rate. Having this information RPM can be calculated by microcontroller. Particularly this project was aimed for measuring RPM of PC fans. So The RPM scale is limited to 1200 – 3200 RPM. Digital RPM value is displayed on standard LCD. Be sure to check out another great PC fan speed tester. Continue reading