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91  Using Arduino / General Electronics / Re: altitude detector on: April 05, 2013, 11:08:32 am
If all you want is relative difference in altitude between your location and some other location, say a low-altitude weather balloon, you can use a MPL115A2 on the balloon and one at your location and the difference in atmospheric pressures will tell you the difference in height.  Using the differential pressure method reduces the effects changes in the weather, note I said reduces the effects not eliminates.  After working on systems like this I can tell you the baro method of height estimation will be more accurate then the GPS method in the majority of cases.
92  Using Arduino / Project Guidance / Re: Building a Spring Tester on: March 22, 2013, 09:48:42 am
Have you thought of interfacing to a digital linear scale to make the linear measurements of the spring position?  There are quite a few web pages that discuss interfacing an Arduino to linear scales, I have not checked whether they have the requisite resolution.

To get the required motion you could use a linear actuator rated for the force required and use the arduino interfaced to a motor control board.

Free advice and worth every cent!
93  Using Arduino / Project Guidance / Re: Load sensor amplifier on: March 05, 2013, 12:11:56 pm
I would buy this IC http://www.ebay.com/itm/INA125-Instrumentation-Amplifier-w-precision-voltage-reference-INA125PA-OpAmp-/181049159026?pt=LH_DefaultDomain_0&hash=item2a275eed72
I have used INA125's for load cell amps in the past and this has the benefit of a precision voltage that you can excite the load cell with.

For schematics get the datasheet for the IC and read it.
94  Using Arduino / Sensors / Re: Sound Sensor on: March 02, 2013, 01:53:37 pm
I think you could build a small sensor board that would trigger an alarm based simply upon the volume.  The false alarm rate would probably be very low given that the ambient noise level in the kennel probably rarely gets to a volume close to that of the dog barking.  I do not think you need a noise canceling system given the relative volumes. 

You could set up the sound sensor to light an LED and monitor it to see if you have a false alarm problem so as not to confuse the dogs.  Running just the LED with the sensor would also be required so you could set the threshold at a level to ignore ambient but trigger on barking.  A filter on the sound sensor based on frequency could further reduce the false alarm rate.
95  Using Arduino / Sensors / Re: Self-Levelling with MPU 6050 and 2 servos on: March 02, 2013, 11:55:36 am
Search this site directly or Google the world and you will find places to start and then you can help us by asking direct questions about aspects that you do not understand.  Starting out with the broad type of question like you have will neither help you or us.
96  Using Arduino / Project Guidance / Re: arduino +100Mhz radio jammer on: February 23, 2013, 03:19:11 pm
I am getting great chuckles that anyone over the age of 10 years of age would except what is said on any Wiki page when it comes to laws.  I do not think the I read on Wiki-XYZ would be a very strong defense, at least not strong enough to bet on. 

But hey go for it! You could be setting precedents and if not you may get to meet a bunch of people that you normally don't in your normal walks of life.
97  Community / Products and Services / Re: PCB online service - best price - fast delivery - NO TOOL cost on: February 22, 2013, 11:54:55 am
PCBoards,

It is dangerous to advertise things like the best prices especially in the Google age, I used your online pricing tool to estimate the cost of a small board and it was at least 10 times more expensive than some of favorite vendors like Seeedstudio.com.

Good Luck
98  Using Arduino / Project Guidance / Re: Senior Project (Kickstart) on: February 22, 2013, 11:24:26 am
I worked as the technical director for the Desert Hawk UAV product while at lockheed and one of the difficult problems for small UAVs is an accurate altitude solution.  Actually I should say the height above ground mainly when coming in for a landing, if you have an altitude that is accurate within say 10 feet you can localize your landing much better and reduce damage also from landing.

People have thought of laser range finders but they are a hard nit to crack given the timing and expense of the APD.  Radar is a possibility as is differential baro altimeters, the GPS vertical error is too high to work for this app.  The differential baro would entail putting one of the high accuracy MEMS baro on the bird and one on the groundstation.  The mission time is too long for you to rely on the original baro reading that you took off with so as you approach for landing you send the current baro at ground level in the landing area to the bird.  The height above ground is a simple calculation based on the difference in baro readings, thus the term differential baro. 

Building a small radar altimeter may be a better approach as then you do not need any changes to the ground station and is a little sexier than measuring the air pressure.  The folks over at DIYDrones may help you on test flights if you share some of your completed hardware, trust me that is very cheap flight testing.

wade
99  Using Arduino / Project Guidance / Re: Temperture/humidity sensor ? on: February 19, 2013, 11:06:33 am
Do you really need to measure the humidity to a resolution of 0.1%, I ask because if you do absolutely do the sensor is going to cost you a lot of money.  Maybe you could tell us what you are using the measurements for we may be able to help you on your requirements.
100  Using Arduino / Sensors / Re: Pressure Sensor help on: February 07, 2013, 11:02:24 am
If it has to stay within its threshold put one under each leg of the coach.
101  Using Arduino / Project Guidance / Re: Doppler Speed Radar on: February 07, 2013, 10:58:28 am
Russ,

If I can ask what did you pay for the MDU1720 modules and where did you get them?

Thanks
wade
102  Community / Products and Services / Re: PCB Service, less than $100.00 for prototype orders. No tooling cost for reorder on: February 06, 2013, 04:28:07 pm
Real-PCB,

You mention in your subject line and in a post that there is no tolling cost for reorders but do not tell us what the toolong cost is so we can determine what future orders will cost, if you want to be considered for real you should let us know what the tooling cost is.  You say factory costs in China are more than $9.90 for 10 boards maybe you should just contract with Itead.com or seeedstudio.com and making $90 per order that is pretty good money for transferring orders.

103  Using Arduino / Sensors / Re: X-Ray detector/sensor on: February 03, 2013, 04:07:51 pm
What good comes out of X-raying a car, I would think the metal skin would either absorb or scatter all of the radiation leaving little to image with?
104  Community / Gigs and Collaborations / Re: Help wanted on hardware,software for pay on: February 01, 2013, 05:46:49 pm
Have you chosen a method to measure the sound pressure level (decibels)??  In general the SPL is not as easy as just measuring the output of the amplified output of the mic, many methods require the analysis to be done in the frequency domain and Arduino may be over tasked depending upon the rate that you want the measurements made.

I would be interested in implementing a method for measuring the SPL and the force (load) sensor, if you have researched and determined the best way to measure the SPL for your application.  I want you to choose the method for two reasons; 1)  I am not an acoustics engineer and 2) your concern about repeatability concerns me as it may be hard to deliver if the method does not match the environment enough.  I would also require you to quantify what the repeatability requirements are, by doing this we both have the same threshold for completion and this is important for both parties to be happy at conclusion of the project.

Send me a PM if you want to discuss this offline and I will give you my direct contact information.

It may sound like I am being a PITA I just want you to understand what I need to complete the project satisfactorily,

wade
105  Using Arduino / Project Guidance / Re: torque sensor on a bike on: February 01, 2013, 03:29:53 pm
I think a load cell on the pedal would be the way to go.   To get the signal off the pedal either use Bluetooth or a slip ring to directly get the electrical signals, power and ground off the rotating pedal.
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