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16  Using Arduino / Project Guidance / Re: Read a frequency from 0 to 2700Hz with the arduino on: July 16, 2014, 09:23:35 am
At your max frequency of 2700 Hz there would be about 6000 clock cycles between peaks so the processor has more speed than is needed which is a good thing.

If the peaks are well-defined like a square wave input you could attach the signal to one of the interrupts and increment the counter every time the interrupt is triggered.  Use a comparator with a variable threshold if the peaks are not well defined and then attach the output of the comparator to the interrupt pin and count them as defined above.

Hope this helps,
wade
17  Community / Gigs and Collaborations / Re: PCB design support wanted on: July 14, 2014, 03:05:57 pm
I have seen some of Crossroads PCB designs and can say you will get a very good design.
18  Using Arduino / General Electronics / Re: Questions about an amplifier circuit on: July 09, 2014, 05:56:46 pm
I thought I was addressing his questions about the caps and the resistors, so I reread my post and I still think that is what I answered.  I was not answering a question on non-inverting or inverting amps, so your response brings me pause.

19  Using Arduino / General Electronics / Re: Questions about an amplifier circuit on: July 08, 2014, 02:11:22 pm
The first capacitor acts as a blocking cap it blocks the DC component of the signal passing the rapidly varying portion of the signal.  The role R10 is too act as impedance to the rapidly changing signal the cap then provides a path, the DC component of the signal just goes to ground through R10, the value of R10 is arbitrary.
20  Using Arduino / Project Guidance / Re: Sun position calculator - i'm looking for good code to calculate values on: July 04, 2014, 09:12:30 am
One common mistake when using code to estimate angles and such is that the computer generally does it's trig calculations in radians and us humans think about angles in degrees.  Maybe this mistake is not common to the rest of the programming world but for me unfortunately that mistake has been common for me in the last 30 or so years.
21  Topics / Science and Measurement / Re: ph-logger from cheap ph meter from DX on: July 02, 2014, 12:11:43 am
Since it is known that the chip driving the LCD is a ICL7106CM44 why not build a buffer circuit with an Op-Amp which would provide a high impedance input to apply the signals coming from the In-High and In-Low pins (from the datasheet) and read the output of the buffer using the Arduino's ADC, or an external ADC if you want higher resolution. 

Don't get me wrong I applaud AlexShu's solution as he did some very fine work of decoding the output of the LCD driving chip I am just thinking about starting at the other end, the input side of the ICL7106CM44.

wade
22  Using Arduino / Project Guidance / Re: closure logger on: July 01, 2014, 11:02:31 pm

Dave,

Thanks!
23  Community / Gigs and Collaborations / Re: Gig and possible employment opportunity. on: June 30, 2014, 03:06:30 pm
I sent you a PM.

Thanks
wade
24  Using Arduino / Project Guidance / Re: closure logger on: June 30, 2014, 02:44:18 pm
For the life of me I can not find the example I am looking for but there are inexpensive linear scales http://www.ebay.com/itm/12-DIGITAL-DRO-TABLE-READOUT-SCALE-for-BRIDGEPORT-/310224430119?pt=BI_Heavy_Equipment_Parts&hash=item483ad12427 that people have written libraries to read them.  The scales provide pretty decent 0.001" accuracy and hold the readings for long periods of time under power.  Sorry I think in inches but 0.001" is about 0.025 millimeters so I believe your requirement is met and I am pretty sure they come in at least 25 cm lengths.

Someone else can probably chime in and direct you to the the code examples to read these scales.

Hope this helps,
25  Using Arduino / Sensors / Re: Material Transparent to Ultrasonic on: June 29, 2014, 01:37:12 pm
Or you could try using special thin latex or rubber that is commonly sold as "something for the weekend"

I imagine one should not go for the french ticklers but just the old plain ones.
26  Using Arduino / Project Guidance / Re: minimal 24h weather forecaster on: June 27, 2014, 08:54:48 am
How about monitoring the output of the panels and using them when the output is above some threshold.  You could buy a smaller solar panel that you monitor in real time for output then you would only turn on the larger array when the smaller one is above some threshold.

wade
27  Using Arduino / Project Guidance / Re: is there any anti jamming arduino module for GPS and GSM modem? on: June 25, 2014, 04:05:43 pm
The best way to help keep a GPS from jamming is to first realize that the GPS signal is below the noise floor and is exploited through coding so any noise in-band will cause problems.  I worked on early small UAVs and we used a lot of ripstop nylon that had EMI shielding on it, we would shield the noise emitters and the GPS module seaprately.

28  Community / Gigs and Collaborations / Re: Help save the Vultures with a 10DOF on: June 17, 2014, 12:08:59 pm
That is a face that even the mother couldn't love.

Even with the above comment I am willing to pitch in on this project.  I am an engineer by training so I try to frame any project early on with the requirements.  I understand that the requirements first route is kind of boring because we all would like to do something because that is exciting and fun, no chance of letting the magic smoke out when you are just working with pencil and paper.  Here are some questions I have after thinking about this project for 5 minutes:
  • Does the egg have to weigh roughly the same as other eggs to spoof the Vulture?
  • Can the egg be replaced if the battery life is a problem, you put the original in why not a second one?
  • Given the real eggs and the fake egg will have different weight distribution the fake will move differently from the real eggs, is this error going to be too high for the study?  One being liquid changing to a bird with structure makes it difficult to make a fake egg close to a real egg.
  • What is the maximum distance allowed between the egg and the RF recorder or repeater?
That sums up my concerns after giving the project a very small amount of thought, if you would like to have me help out leave me a PM.

Thanks
wade
29  Using Arduino / Project Guidance / Re: i need help for my graduation project on: June 16, 2014, 11:55:48 am
I would hate to be the test subject in the wheelchair during the test phase, or for that matter at any time in the life of the chair.
30  Using Arduino / Project Guidance / Re: eye blink sensor on: June 16, 2014, 11:45:17 am
I would urge caution on using an IR LED shining into the eye for long periods of time.  I know most of the IR LEDs you can buy are considered eye safe but I am not sure those thresholds take into account long exposures.
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