Car launch control ( RPM limiter)

Other Hardware Sensors
1

hello :slight_smile:

im doing a launch control to a friend car.

I want to know if we can connect and inductive sensor to arduino and how we can convert the signal to rpm;

thank for your help and sorry by the English ( I speak portuguese :smiley: :D)

2

What do you mean by "launch controller"?

Give some details of how and what you want to do.

Weedpharma

3

launch control is a system to limit the RPM of a car engine,
and to limit the RPM I need to know the current RPM of the engine,
that way I need to connect an inductive sensor to arduino

4

To be able to read the RPM, we need a lot more information such as where are you going to measure it and what type of signal is expected.

Then, how are you going to use that information to actually limit the RPM?

Weedpharma

5

The sensor produces AC current, and I will cut the ignition to be able to control RPM

6

But the only thing that I need to know is if an AC inductive sensor can be connected to arduino, i think that with an bridge rectifier and a voltage divider the problem of AC current is solved
the voltage divider is to limit the voltage (5v) going to arduino

7

You could use a Schmitt trigger circuit.

This will limit the voltage at a fixed point rather than using a voltage divider that will vary with the voltage generated by the pickup.

Weedpharma

8

If the car is fuel injected, there should be a tach signal coming from the ECM.
A lot of times it is a 5v square wave so no need for an inductive pickup.

9

weedpharma

I prefer the voltage divider, for example 4000rpm = 2,4v, in my opinion the variable voltage its better to work in arduino, more easy to use in my case

Detown

the car is from 1989, it have eletronic injection but the tach is mechanical (with a cable from de gearbox);

10

The tach signal I am referring to is not necessarily used to drive a tachometer. It is used for other systems ,such as cruise control that need to know engine speed.
Most cable driven tachs that I have seen drive it off of the camshaft or the distributor which turns at half of crank speed. They do this to keep the speed of the cable at an acceptable level.
What kind of car is this. I bet if you look at the pinout for the ECM you would see a pin that says tach ref or something similar.
Also the pin that sends the trigger signal to the ignition module will be a 5 or 12v square wave.