Tachometer Project

Using Arduino Project Guidance
1

I am using an arduino for a tachometer project. It will have outputs for several LEDs (green, yellow, and red corresponding to different engine speeds). The car has a factory RPM gauge, but I am adding a second tach using LEDs for this project.

The signal that goes to the factory tachometer is a 0-5v pulse for each revolution.

I was wondering if I could tee of this signal line and feed it into the arduino input, and use the PulseIn() function to do this? Could I use PulseIn somehow to take this signal and use it to output my LED tach?

Thanks, any input is appreciated.

2

I would try feeding that 5V tacho signal through a 22K resistor to an Arduino input pin that supports interrupts. Position the resistor at the Arduino end of the wire to avoid noise pickup. Then I would time the interval between pulses in the interrupt service routine, and work out the RPM from the interval. See Hall Effect Sensor Question - #3 by dc42 - Sensors - Arduino Forum for an idea of the code you need to implement this.