Vacuum controlled dimmer switch?

A customer has asked me to build in his car, a lighting system that would brighten and dim based on turbo boost pressure.

What I need: An electronic device that can receive and interpret air pressure and illuminate some lights based on what the pressure is reading.

Pressure ranges from -7lbs to 21lbs. anything below 0 will produce no light, and gradually as the pressure builds too 21lbs, the light will slowly illuminate.

0 = no light

5 lbs = 25% light illumination

10 lbs = 50% light illumination

15 lbs = 75% light illumination

21 lbs = 100% light illumination.

This will be a 12v set up. Anything anybody can offer would be wonderful.

I am relatively good with wiring but when it comes to boards and programming, I'm not literate.

Anything you can contribute would be wonderful. thank you.

Buy a sensor that is made for that. I think it is called a MAP sensor, but a MAP sensor is also to measure the pressure of the engine input, you need one that can measure vacuum.

Split it up in two.

Get a 10k pot, and connect it to Arduino's +5volt, ground, and an analogue input.
Try to write code that uses the pot value, and changes it into LED brightness.
e.g. the onboard LED, connected to pin 13.

Then think of interfacing the sensor to the analogue input.
Leo..

going from -7 to +21 means your physical device has to be able to measure on either side of zero. very hard to do.
but, since you do not care about anything below zero, you sensor choice is much easier. seems to be no shortage of sensors you can get.

I would assume that the vehicle is already fitted with some electronics. and if there is a pre-existing sensor, you should be able to it into that.

I would highly recommend that the signal come into an op-amp so that you have control of the zero, span and also be able to isolate your use from the car. hate to have your sensors pull down (up?) that and kill the boost.

I will continue to look for a device that exists already but If all else fails, I will have to buckle down for a night and engineer one. I have never let a customer down before and your comments tell me that this is within my scope of comprehension. If anyone is interested and enjoys this as a hobby, if designing one is something you are interested in, remember that this is a customer paying for the part and not my personal money. If you put it on eBay (being that transactions through eBay are secured with the option of a return policy if the item does not work) I would be more than happy to pay someone for their craftsmanship.

Get some specs for the car and find out if the boost pressure is available from the OBD port.

interesting idea

customer has accessport plugged into OBD port for continuous data logging of engine performance, thats a no go.I know Honeywell sells multiple air pressure sensors that would do perfect, but I don't know what arduino board to buy, how to write code or transfer said code onto the board, I don't know if I own a soldering gun small enough to do the job without destroying other components...

dave-in-nj:
going from -7 to +21 means your physical device has to be able to measure on either side of zero. very hard to do.

You just need a sensor that responds to absolute pressure, rather than 'guage pressure'.
Then all readings are in the positive direction.

bugeyespool:
customer has accessport plugged into OBD port for continuous data logging of engine performance, thats a no go.

OBD port splitters exist ($10 on Amazon). No guarantee your "accessport" and the assumed bluetooth interface will work together but I'd assume if only read operations are taking place that they would.

it seems that you have to read the boost pressure.
in order to do that, you need to either add an additional sensor (lots and lots available.)
or tie into one that is already on the vehicle.

e-bay pressure transducer and look for one around 30 psi.
one side is threaded so you can connect whatever you want.

as for the arduino side, the project is rather simple.
you input the analog value from the sensor. that will be broken into 1024 steps. so, if you have a 30 psi sensor, your steps are not that close. makes it easier.

using your 5 psi threshold, you would want to have it really start at say, 5.1 psi on the increase and then 4.9 on the decrease. that way, you eliminate shuttering if the pressure is sitting on 5.0. this is called hysteresis and eleminates that flip-flop when on the razor edge of the reading.

HOW you dim the lights, that is something else.
probably best if that was a separate thread.

but, you can take a NANO, connect it to a screw terminal shield ebay - 381125347737
and read your presure sensor.

I would offer that if you have room for a larger light, you could use a neopixel and control the color of the lights. http://www.adafruit.com/products/1312

If this project were to reach fruition I think it would be realized that the level of pressure cannot be determined since the level of light seen at the led has no reference. Is that led showing 5 or 10 PSI?
Well, it's glowing but how would one be able to tell just how brightly it is illuminated? Ambient light conditions will affect any interpretation. I suggest an led bar graph display. - Scotty

I should have been more clear, this light does not serve any real purpose. The car is a 2002 built wrx and it has at least 7 gauges monitoring different things under the hood. The LED lights will sit inside the air vents and are mainly for use of drivers peripheral vision so he does not need to look directly at boost gauge but rather see illumination throughout the car and know that he is within boost threshold. Its like a shift light for him, he said. He drove with it before but has lost contact with the owner of the car, otherwise we would have asked him.