Simple Circuit Design : Car Accelerator calculator

[Agent 009]

The topic is simple, but I really need a hand on the design:

I have a car that has a velocity sensor, and what's needed is the acceleration. Well, from Newton's law of motion (or somethin' like that) we have:

a = dv / dt

So I thought a simple voltage differentiator would do the job, assuming that the velocity sensor give the speed as an increasing (or decreasing) voltage. But that's just nice so far. And that's how far I got: I have to use just capacitors, resistors (variable or not) and an op-amp (of course). Guys, if any of you know a good method to board this kinda problem, please I need some help! :lol:

 

[Roff]

Check out National Semi's AN-20:An Application Guide for Op Amps. There is a section on differentiators. You might want to use a modern op amp.

 

[Klaus]

Do a google search for accelerometers. There are quite a few available in chip form, needing very little by way of external components.
The output is straight acceleration, some chips do more than one axis.
Get the application notes too, to find out how to correctly orient the chip.
I have used the Analog Devices ADXL05 but that may have been replaced by newer versions.
Its the simplest way to get an accurate acceleration output.
Klaus

 

[Roff]

Do a google search for accelerometers. There are quite a few available in chip form, needing very little by way of external components.
The output is straight acceleration, some chips do more than one axis.
Get the application notes too, to find out how to correctly orient the chip.
I have used the Analog Devices ADXL05 but that may have been replaced by newer versions.
Its the simplest way to get an accurate acceleration output.
Klaus

Good advice, Klaus, but this looks like a homework assignment to me. Here's a quote from Agent 009:

I have to use just capacitors, resistors (variable or not) and an op-amp (of course).

 

[Agent 009]

Man! The site was very instructive.
Thx, Ron H!! :wink: