Ok let me start off with this - I am very new to this, I know next to nothing about programming or any of this.
I have a very very important project I am working on and I need to measure and graph high G-forces. I only need 1 axis, this is the accelerometer I want to use http://www.sparkfun.com/products/9332. What all do I need to go from this accelerometer to graphing the G-forces on my computer? I can use Mac or Windows. Are there any programs or whatever that are going to need to be written or are there programs that will do this for me? I have heard that they change voltage output depending on the forces, if I cant graph the G-forces, can I graph or record these voltages and then convert those to G-forces?
Thanks, i'll be sure to read thoroughly through the post and maybe contact him.
Very very important means if the real world numbers are close to my numbers "on paper", well.... I would be able to retire.
The part you referred to has a very large range of 125g, something that I have some doubts that the mounting PCB will be able to endure especially during an impact. With a constant acceleration, say in uniform circular motion, it's a different story. What experiment are you doing? Something too secretive to discuss?
Here's what I do with a 18g accelerometer:
The middle of the page has a POV display which registers 9.71g
You're right. It's big. My point is, does a PCB like that sold by SFE survive 250g if the OP intends to measure an impact with it? Normally I read from parts that survives xx g of impact. How much impact in terms of g can that PCB withstand?
I will be testing a new technology for car crash safety. The sensor will only handle these forces momentarily and should't ever reach that 250G rating, I would assume no more than ever reaching 80Gs. I could even run wires to that the only thing experiencing these forces is the sensor itself and all the other circuitry is stationary.
That was exactly what I was concerned, a sudden change of acceleration. Plus, do you know the time scale of the crash? I guess in milliseconds. Hope the response time of the accelerometer is fast enough.
The device outputs an analog signal that you read as fast as you possibly can (Once every 100us typical with an Arduino, that's 10K samples per second) and record it for later analysis. If 10K samples per second is Ok... you're good.
As for the G-force. What kills you isn't solid objects like the PCB, it's air trapped in places, like under a chip. When that chip hits the wall, it's going to drive down onto it's pins, focusing the force on the much smaller area. The PCB, a solid object, pushes back, crushing the solder joints and underlying plastic structures with amplified force. Think about a typical QFP package... Only a tiny percentage of the total area is the actual pins. The connections from the chip to the pins becomes the weak link if there is any air under the chip.
If I was going to make a sensor I thought would have to walk away from A 25Og hit over and over and over again, I would vacuum encapsulate the entire sensor in epoxy.
that's not that hard. Vacuum pump, bell jar (Or other sealable container), mold for the epoxy. Put the PCB in the mold, mix the epoxy and put it in there, then close the bell jar and turn on the pump. If this can be worth what you think it is, then doing it right is the way to go.
