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1  Using Arduino / Sensors / Re: Measuring joules/watts? on: March 01, 2011, 11:21:51 pm
Sweet! I should have known SparkFun would have something. That looks just about perfect.  Thanks so much!
2  Using Arduino / Sensors / Re: Measuring joules/watts? on: March 01, 2011, 06:20:23 pm
Cool.  So, measure the volts and amps coming out of the panel, because W = V*A.  Makes sense.

Being an electronics NOOB, can anybody recommend some Arduino-friendly parts / circuit diagrams for the ammeter portion? 
3  Using Arduino / Sensors / Measuring joules/watts? on: March 01, 2011, 01:15:35 am
I would like to do a little project with a solar panel, something to measure the actual watts coming out of the thing, and an Arduino to integrate the panel's output over time.

However, I haven't any idea of how I would build a circuit to measure the actual amount of power the panel is producing.  Is there an off-the-shelf component that will measure that for me?  Or measure some  related value(s) through which I can calculate the watts?

Any pointers to circuit diagrams, wikipedia pages, or anything to help me get going would be greatly appreciated.
4  Using Arduino / Sensors / Re: Advice for sensors with LONG leads? on: February 23, 2011, 07:09:10 pm
Thanks, Grumpy_Mike.  The AD537 looks like a good option.  The datasheet even includes a helpful two-wire schematic with frequency-to-voltage conversion on the receiving end!  Looks like that, plus some experimenting, calibration, and a bit of software will do the job.
5  Using Arduino / Sensors / Re: Advice for sensors with LONG leads? on: February 23, 2011, 05:37:10 pm
Well, the sensors I happen to have on hand (well, at home) are Phidgets sensors; I don't know specifically what part numbers they are.  But, they come with an easy-disconnect connector, giving access to the sensor board's raw analog +/-/ground lines.  I was planning on plugging these straight into the Arduino's analog inputs.  I'm certainly willing to buy something else if it's affordable and is in some way just the thing for the job.  Basically, I'm open to anything that will help me just get the job done.

I would, ideally, like as few wires as possible running over that 70 foot span.  I would DEFINITELY like to avoid the complexities of separate power et cetera for the remote location.

Given that I haven't the slightest idea how to do voltage/frequency conversion but am willing to learn, can somebody point me towards specific parts, schematics, tutorials, or whatever that can at least get me started down the right road of research?  At the moment, I know little enough that I feel like I'm fumbling around in the dark.  Thanks!
6  Using Arduino / Sensors / Advice for sensors with LONG leads? on: February 23, 2011, 04:51:22 pm
The project I'm working on needs to monitor temperature in two places. One, at the location of the Arduino.  Two, about 70 feet (20+ meters) away.

Can I just solder reeeeealy long lead wires onto that temperature sensor, or will goofy electronics effects I know nothing about come into play to mess me up?  And if long lead wires aren't going to work, what should I do?

Any and all advice greatly appreciated.
7  Using Arduino / Project Guidance / Re: Automatic Fan Control: advice needed on: February 22, 2011, 05:48:22 pm
Thank you.  That helps.

I do not plan on varying the fan speed.  No PWM, just on/off.  I know I'll be using a standard 120mm PC case fan or CPU fan (whatever I can find that's QUIET and inexpensive), something that moves about 70 CFM, and while most of those support variable speed use these days I don't see why I'd really need that.  Worst case, that'll be a version 2.0 improvement I can make.

Looks like SparkFun makes an "Ardumoto motor driver shield" that is what I need to switch the fan on/off while powering it separately.  Here's a new block diagram:

Anybody have any ideas about the LONG sensor leads issue?
8  Using Arduino / Project Guidance / Automatic Fan Control: advice needed on: February 22, 2011, 02:43:25 pm
This is my first post here, so please be gentle.  :)

So I'm building a solar furnace up on my roof to help heat my house in the winter.  Basically, one of these:

Except not made of pop cans, and running the full 60 foot length of my roof's ridge line.  Whatever.   

Here is a high-level block diagram of what I'm thinking:

The idea is pretty obvious: I want Arduino to monitor the indoor house temperature and the temperature inside the solar box, so it can turn the fan on automatically when it makes sense to do so.  Basically, turn on when there's enough of a temperature difference for it to be worth running the system.

In the end I want to mount all this permanently.  I'll fashion a housing to mount the display, control buttons, and Arduino board behind a nice wall panel.  I am BRAND NEW to the whole world of Arduino (last time I dabbled in hardware, everybody was still building their own HC11 boards, and that level of electronics was beyond me), so don't assume that I know anything.  Here are my issues and questions.  Any and all advice is very much appreciated.

1. What should my approach to power be?  Since it's going to be mounted inside the wall, obviously I want to run the whole thing off of house current.  Does an Arduino kit come with an appropriate wall wart or something else I can hack to permanently join it to my house current?  (I told you I'm brand new at this.)  Can I power the fan _through_ the Arduino somehow, or will I need to supply the fan with its own 12V supply that the Arduino merely switches on and off?

2. Sensors.  The indoor temperature should be easy, right?  It seems like there are plenty of samples and tutorials for temperature measurement using Arduino, all of which have the sensor itself positioned very close to the board, and that's the same situation for me.  Measuring the temperature inside the solar box, however, is another matter.  That's up on the roof, and the way this thing is going to be mounted in practice, the ideal location for measuring the box temperature (that is, at the output end), is roughly 70 feet (20+ meters) away from the Arduino.  Will the normal methods of hooking up a thermistor to an Arduino work at that kind of distance, or will the cumulative resistance of the sensor wire itself become a problem?  Less optimally, but likely still acceptable, I could measure the temperature at the closer end of the solar box, which would only be about 10 feet (3 meters) away from the Arduino.  So, is there a way I can get reliable temperature readings from 70 feet away, or should I give up and measure at the near end of the box?

3. Control buttons. Is there anything weird I need to know or plan for about hooking up buttons (momentary contact switches)?  Do we de-bounce buttons in hardware or software these days?

4. Status display. It seems that the Arduino crowd is pretty fond of the HD44780 style character displays, which is just fine for my purposes.  Besides the display itself, what other parts will I need to hook it up?

5. What Arduino should I use?  It seems there are quite a number of models out there; what models are going to have enough inputs to deal with two buttons and two sensors, and outputs to control the display and the fan?  Or is this a non-issue?

6. What else should I have asked about?  Since I'm brand new to all of this, there's probably something all you experienced folks know I should be worrying about, but I'm still too clueless to ask.  Help a brother out, yeah?

Thanks in advance!
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