Will Pay for Help Need Design

What sort of impact/pressure/sensor?

For that price you might be able to get the bare bones of a simple analog design, including full adjustability, but I'm pretty sure that a digital design will have a higher design price tag. In fact, you could probably get an analog design here on s.e.d. for free. Or at least a conceptual design, perhaps requiring a few nitty-gritty details to work.

Money! $$$$ :) This project reminds me of this:

Didn't somebody already post that chip... not sure. Anyways.. I program PIC microcontrollers the long hard way...in assembly language so it's going to cost more than $200.00 (Sneaky smiley :) ) Also, I have a $1000.00 min. Maybe you'll luck out and a student will make this a term project for $200.00. D from BC

Not too sure. Anything to get the job done i guess. it's will be used to sense impact rather than pressure.

I would really prefer a digital design. And i am looking for more than just a design i would like a prototype. It's for my sons science project. I Can pay $300 for digital.

Are'nt there easier ways to program a PIC microcontroller besides assembly?

Yes.. For your application , doing the code in a high level language like C would be preferred to reduce software development time. I'm only set up for assembly coding and didn't learn C compilers for PIC uC's yet.. Goofy me... D from BC

Your biggest challenge is finding the right sensor. What kind of impact (in G, PSI, N) and how (soft or hard contact)? How are the sensors arranged in the application?

What will he learn from this?

Connect a cheap crystal microphone (Radio Shack) to an oscilloscope (eBay) and you're done except for mounting the mic.

I'm thinking PSI sensor would be best. the application is complicated but i guess the closest application would be a light saber that would flash the different colors based on the impact.

It sounds like you need to measure shock, not pressure. Something like the murata shock sensor PKS1-4A10 would seem appriopriate. Its cheap and available from FARNELL or other such electronics stores. Its a Piezo ceramic element that generates voltages when deformed. Of course you still need to attach the processing electronics. As the others have suggested in this post, I'm thinking an analog solution would be better, unless you know how to program microprocessors. As to paying someone to do it, I doubt you'll find anyone who'll do it for that sort of money. I'm forever seeing potential clients walking in to my design office thinking I can just whip something up in a few hours. Theres a lot of pain staking detail to any project that few people ever know about. Besides I think you're doing your son an injustice. He needs to do this himself. How else is he going to learn anything and grow through the experience.

Regards Robert

Thanks Robert. I'm willing to do the work myself I'm just very new to this and most of the experience i have is moding Ps2s and Xboxs. As for my son, it's a small part of the project that has nothing to the with his actual research, i would buy it in the store if i could. It's like making a pen to write his research or just buying a pen. The murata shock sensor PKS1-4A10 seems like a good idea and i would be willing to go analog.

As far as the force; think of a baseball hitting a bat. Thats the kinda force i'm talking about.

Hai iam job Mathew. I have been 10 years experiance in the field of electronic designing. I can help you Your requirement is simple. First you have to identify the maximum pressure that you want to meassure. then select suitable transducer for converting pressure to corresponding electricl signal. We can controll the brightness of the LED,s using PWM schem. The duty cycle of the signal is corresponding to the input signal which is from transducer. The PIC series microcontroller is suitable for this type project. If you want any help pls contact to me. Regards, Job Mathew

Well, what you already may have learned from this thread is that no one is ever going to be able to pull this off for $300.

The other thing that you may or may not have learned is that people, however willing, may not be able to help you with your problem if you're so unwilling to spill a few facts about the project. Go ahead and tell us the application; what object is hitting what other object & at what speed etc. insted of using idiotic pictures like "pen to write the paper" or "light sabers". The only way to come up with a good solution is knowing the whole problem.

Mind you, in this group there are people who are working on big $$$ projects that they can't talk about, yet they reveal a lot more of what they're working on than you with your kid's "science project".

robert

Gawd - for school project it has to be simple so $KID can explain how it works.

1) Buy a piezo-electric gas igniter or one of those throw-away piezo lighters. 2) Rip out the piezo element (a ceramic thingy, usually excited by an impact mechanism) 3) Stick a capacitor in parallel with the element. A piezo element will give off a charge proportional to the force it is compressed with *so* the voltage across the capacitor will depend on the capacitance and the force. Experiment. Possible put an EHT rectifier diode in series with piezo and capacitor so you get peak clamping fer free. 4) Build a comparator stage to drive a LED depending on the capacitor volatage. 5) Build two more for the rest of the LED's

5a) maybe you need a buffer amplifier before the comparators.

Make a suitable plate to hit that will transfer force to the piezo element.

>

Get a balloon, or whatever... Something to catch the "pressure" and convert it to a volume of air.

Then, get a supply of World Magnetics pressure switches (~$15 each, in low quantities from Digikey). They come in different pressure ranges, from 1 to 50 PSI, and even some that are adjustable. Search Digikey Part#: 384-1015-ND for example, or just "World Magnetics".

Parallel a few these with a bunch of 1/4" plastic tubing (like for a fish tank). The switches are Form-A output, and rated for enough current to light LED's no problem. Wire a battery and some dropping resistors. You don't even need a circuit board.

Done!!

Hi, Just to sense the impact and pressure we can use the strainguage in the bridge circuit and for the display we can very well use LM3914. Calibrating the sensor would be a tricky issue in my view. The whole circuit will not cost more than $30.00 best of luck.

On Wed, 07 Feb 2007 18:48:17 -0800, ezbuyy wrote: ...

Whaddaya, some kind of Yuppie Repugnacrat?

You want to pay money to short-change your own flesh-and-blood's education?

Get the kid to the library, and make him learn what he needs to do to accomplish this; otherwise you're just buying him a ticket to a lifetime of ignorance and probably burger-flipping or management.

Is that your goal? Train the kid to be a manager by teaching him how to cheat?

Or maybe you want to guide him into a career as a politician.

If that's the case, I'll do the project for you for two hundred fifty million dollars, half in advance, and half at completion.

Cheers! Rich

It could be done with three comparators and a sample-and-hold, but I thought we had a policy around here of not doing people's homework for them.

Thanks, Rich