Useing Analog Speedometer with Arduino

Projects General Guidance
1

Hi, I´m trying to understand about how to use an analog speedometer with arduino, so far as I have study the analog speedometers use a wire that moves a magnet and it creates a current depending on how fast it moves.

Now I´m not working on it at any special speedometer, just would like to understand how to do it so I can implement it then.

Please if some one has done it before would it be possible to receive any advice?

Regards

2

I know mechanical speedometers, where the rotating magnet pulls the needle against the force of a spring.

An electronic equivalent supplies not much current, less than you can measure. At least the wire should be replaced by a coil, best with an iron core, to get a higher signal. An electric generator would be the right sensor, an AC (or DC?) motor can be used as well.

3

I think most newer electronic speedometers read a '"pulse" signal, not a voltage. The signal is generated by a Vehicle Speed Sensor (VSS) that generates so many pulses per mile. I am using a hall effect sensor attached to the front wheel of one of my cars and sending the signal to an Arduino to calculate the vehicle speed. The same signal could be used to drive an electronic speedometer.

4

Hall effect sensors are so tiny you can put them almost anywhere. Counting the bolt heads on a drive shaft or brake disc is very easy.

You could put a sensor inside the speedometer itself. In that case I would use a QRE113 optical sensor and paint a black or white line on the spinning disc.

5

joamanya:
Hi, I´m trying to understand about how to use an analog speedometer with arduino, so far as I have study the analog speedometers use a wire that moves a magnet and it creates a current depending on how fast it moves.

Now I´m not working on it at any special speedometer, just would like to understand how to do it so I can implement it then.

Please if some one has done it before would it be possible to receive any advice?

Regards

By "wire" are you referring to the multi-wire, twisted steel cable inside the flexible housing that is clamped/screwed to the back of the speedometer mechanism?

Paul

6

Are you trying to read the speedo or make the speedo work as some kind of prop or something (eg steampunk).

If the second then you will be using PWM and a transistor.

Mark