Sensor signal modifier, is this possible?

5.0Rick

Hello Everyone,

· Is it possible to create a microcontroller cirtuit that can take a sensor signal (say a MAF Mass Air·Flow Sensor - 0v to 5v as air flow increases) and output a signal that is inverted (5v to 0v as air flow increases)? Basically would like to be able to modify the signal + - throughout the operating range in order to fine tune the output. I want to replace the restrictive flap door style Air Flow Meter with a Hotwire Mass Air Meter. Someone has already developed a circuit with an Op-Amp (LM324N)·that can do this, but it has very limited adjustability. Can someone please point me in the right direction?

Thanks,

Rick

Tracy Allen

You could do that, but the Stamp will require external circuitry, including an analog to digital converter on the input and a digital to analog converter on the output. It would make sense if you need additional processing and control functions.

But if you simply need to invert the signal so 0->5 volts becomes 5->0 volts, a simple VCCS circuit built from an op amp could do that , and easily to swing 0->4.5 volts to give 5->0.5 volts.



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Tracy Allen
www.emesystems.com

Post Edited (Tracy Allen) : 3/25/2006 7:42:28 PM GMT

5.0Rick

Thanks for the response Tracy. I am a complete newbie. Do you know of a beginners kit or can you suggest the best way to learn? or samples that I can use to make my own circuit?

Thanks,

Rick

rockin_rick

You could do this, but the transfer 'curve' of the flap door sensor is most likely very different from the MAF. You'll end up with poor A/F ratios due to incorrect sensed air flows. An error of just 0.1V will make your A/F's way off, and it is completely possible that the difference would be much greater. Unless you are planning on retuning the ECM, you'd probably be better off with an A9L conversion or such.... (if my suspicions of your application are correct...)

Rick