pulse signals from speedo question

[zebedy]

Ok, not giving too much away at this stage as its a winter project. If one wanted to generate an electrical signal at when a car reaches a certain speed say at 70 and again when dropping the speed at say 40, anyone know how it could be done. Been thinking of mechanical ways to do it and have a few up my sleeve, but was wondering if there are any techy's in here that could do it electronically. Ive heard something about pulse signalling but know nothing about it.

 

You've probably guessed why I've ask, but is early days yet.

[Mike_89]

Hall effect sensor or possible through GPS if your not concerned about accuracy.

[Mack]

OBD2 reader with a cellphone/tablet/computer may be an option.

 

Mine can read speed around 2.6 times per second however your will probably need some computer or smartphone programming skills to output a signal.

[Richf]

You can take a speed signal from the ecu .

[zebedy]

this is what I thought, but dont know the "know how" yet, but I will get a fully working active spoiler by next march, engineered from scratch working like the porkies, maclarans, TT.s etc. Its not going to be huge or wild coz its a roadster. It will go up, it will tilt and it will come back down into the boot area. Project Active Z. LOL