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31  Using Arduino / Project Guidance / Re: Powering Arduino from a 12v LiIon Battery on: May 28, 2011, 12:21:19 am
Hi,

Where was the Ebay seller located??

Lately China has stopped allowing Lithium based batteries in Hong Kong Post etc... Bummer! 

I'd love to get some of the batteries I see on Ebay...
32  Using Arduino / Project Guidance / Re: Interactive Art Object Using Arduino+PIR sensors, which parts to buy? on: May 27, 2011, 11:50:13 pm
Hi Mark,

Shipping to Nederlands is not a problem -- the Shipping part.

Nederlands Customs is a problem.. I try to make the value not too high, but Nederlands sometimes charges Customs duty even on the shipping cost!  I would try to mark the shipping cost on the outside of the package so they don't charge the Max.  Let's email offline on business stuff..  But if you have a good low-cost supplier inside Nederlands, I'm sad to say that might be the best option.

About Starter Sets: It depends on if you are comfortable with wiring things up on a breadboard like these: http://yourduino.com/Breadboard-Wire-Parts.htm  but the easy way with lots of different input and output devices you can quickly hook up is an Electronic Brick set like these:
http://arduino-info.wikispaces.com/BrickStarterSet
Click on the image of any device to see more about it, and example software sketches...

Let us know how we can help...  you have a cool project in mind there!


DISCLAIMER: I mentioned stuff from my own Shop...
33  Using Arduino / Project Guidance / Re: Interactive Art Object Using Arduino+PIR sensors, which parts to buy? on: May 27, 2011, 02:41:32 pm
Quote
Last question so far: Do you know how to incorporate the PIR sensor? Do I need a sensor shield? (i'm working with 5 PIR sensors, each has to work seperately from the others)

I just used one of those today for writing up in my Arduino-Info Wiki (http://arduino-info.wikispaces.com/)

Take a look here and you will see how I connected them:

See the discussion here: http://arduino-info.wikispaces.com/Brick-Pushbuttons%26OtherSwitches#Motion

A  Sensor Shield http://arduino-info.wikispaces.com/SensorShield just makes it easy to connect lots of different things to Arduino without the wiring getting out of control..  With cables that plug in etc.. like on this page: http://arduino-info.wikispaces.com/BrickStarterSet


34  Using Arduino / Project Guidance / Re: arduino to arduino - analogue input output on: May 27, 2011, 08:12:28 am
Hi wimbot,

Quote
Ive being using a flex sensor with a piece of newspaper taped on to it and it's working well so far

Can you tell us the source / info on that sensor?? Thanks!
35  Using Arduino / Project Guidance / Re: Arduino Controlled Stage Light Array on: May 27, 2011, 06:16:17 am
Hi,

Are you doing this to teach or demonstrate stage lighting techniques?  Tell us  a little more.

The 12V halogens would be good because they behave much like larger lighting instruments.  The changes in color temperature with dimming, for example, doesn't happen with LEDs.. 

Depends on your objectives....

So, will you be dimming them or doing fast fades?

You could use relays, but then no dimming and perhaps noise??

So, power FETs seem like an approach.  I have used these on 12V halogens.  They could be mounted near the lamps or power source and some distance from the Arduino if needed...
http://arduino-direct.com/sunshop/index.php?l=product_detail&p=60

Or you could build your own dimmer box...


DISCLAIMER: I mentioned stuff from my own Shop...
36  Using Arduino / Project Guidance / Re: arduino to arduino - analogue input output on: May 27, 2011, 04:50:21 am
G8HBR DE WB1FQH,

Great idea!

...especially after I realized that you were talking about what the Colonists call a "PinWheel"  smiley-roll

It has a nice visual and audible feedback to the 'blower' too.
37  Using Arduino / Project Guidance / Re: Plant Moisture Monitor on: May 27, 2011, 03:02:11 am
Hi,

The usual problem with Soil Moisture measurements is poor long-term stability.

AC is needed as an applied signal because of electrolysis effects.

Here's a design that uses Arduino and an H-Bridge like we use for motor control:
http://gardenbot.org/howTo/soilMoisture/#The_local_circuit_-_H-bridge_style

It's basically this:


The idea is to take a series of readings in both polarities and average them. When not reading, set probes so no voltage is across them to minimize electrolysis.

I don't see any code posted for this yet.. more search needed.. Not sure how this can be calibrated other than by experience.

I don't think the 57K resistance is critical...

Let us know what you get working...

I'll build one of these when I get back to Vermont this Summer. Right now I'm in a desert in Saudi Arabia  smiley-sweat
38  Using Arduino / Project Guidance / Re: Heart Rate Monitor with Biofeedback on: May 27, 2011, 02:32:49 am
Hi,

Couple things:

- Can you share the heart rate interface design you are using? EKG? IR pulse monitor etc?

- Take a look at http://www.mikmo.dk/gobetwino.html

Playground Info and Code here:
http://www.arduino.cc/playground/Interfacing/GoBetwino

GoBetwino is a "Proxy" that can control PC software from Arduino.. Probably can control WinAmp etc....

Have fun, and don't get too excited  smiley-roll
39  Using Arduino / Project Guidance / Re: arduino to arduino - analogue input output on: May 27, 2011, 12:48:46 am
KE7GKP DE WB1FQH,

Great idea. I have to set this up for a demo!  The serial-serial makes it easy to do effect-separated-from-cause things..

What's a good "blow / breath sensor"?? 

Years ago I had kids do one where blowing in a hole of a panel activated a valve that blew up balloons.  I used an air flow sensor that was a little vane on a microswitch.  But maybe a thermistor in self-heat mode?? What's easy to get??

Hmmm. Optointerrupter with a bit of confetti? Ideas?



40  Using Arduino / Project Guidance / Re: Feasibility question on: May 26, 2011, 05:10:19 pm
neema_t, I certainly didn't mean to be negative about what you're doing.. and you obviously know what you're doing with the TTL/HC stuff.  And you're not building quantity... 

There are definitely those days when I'd prefer to have hardware problem than software problems  smiley 

What you have defined is feasible for you.  Probably not for many newbies...

Let us know how it works out. And photos!


41  Using Arduino / Project Guidance / Re: Interactive Art Object Using Arduino+PIR sensors, which parts to buy? on: May 26, 2011, 04:53:12 pm
Hi,

OK, I have a few opinions  smiley-surprise

This can certainly be done with Arduino.. It is an interesting idea.  I don't want to tell you exactly how to do it, and I think you can experiment and get an example working first, and there is more than one way to do this, like most Engineering things.

- You need to stop, run and reverse the motors.  Two Single-pole Double-Throw relays can do that.  When one relay is activated the motor would run in one direction, the other relay activated and it runs the other direction. No or both relays activated and motor stops. 

- You most probably need limit switches at the top and bottom of travel. 
  - Just time will not be accurate enough.
  - Counting turns could work, but you still need a known starting point
  - You need limit switches for safety
  - Limit switches should shut off the active relay and signal Arduino. Then Arduino can turn that relay off and later activate the other relay for the other direction. 

- The cable could run through a hole in an arm on a "microswitch" with a "bump" in the cable that catches the switch and switches it.

- Safety: you should probably measure the usual start/run current on each motor and connect a fuse that will blow if the motor is stalled because something failed and the motor is trying to wind the weight around the drum. 

So, you might use a pair of relays for each motor like these:
http://arduino-direct.com/sunshop/index.php?l=product_detail&p=171 DISCLAIMER: I mentioned stuff from my own Shop...! But you can buy these other places too.    They already have transistor drivers for the relays so Arduino can run them directly.    Or you can build your own.. (The schematic diagram is on the Relay page).. 

I suggest you prototype one part of this at a time.. 

You can obviously build good things.. this is just a different set of tools and materials...

Make sense??
42  Using Arduino / Project Guidance / Re: Feasibility question on: May 26, 2011, 02:57:22 pm
Wow, neema_t, that IS ambitious.

Obviously, you understand some logic design with TTL etc....  And that's not a lot of ICs for complex stuff in TTL. I've some some with >256 IC's (not all by myself)..

But that's the Old Skool.  I have to put on my WayBack hat.

I can't help thinking that all this COULD be done with just the Arduino, or at least a MEGA.

The debouncing could be done is simpler hardware, as the Arduino has some hysteresis on it's inputs.

The Encoders could be decoded in software.. 

Maybe I don't understand the project well enough yet..   I'll read it again...  I hate to suggest changing direction, but maybe breadboard a piece using Arduino only??  HHmmm...   Interesting...
43  Using Arduino / Project Guidance / Re: Connecting multiple Arduino on: May 26, 2011, 02:47:08 pm
Yes, RS-485 would have been my suggestion.  Plenty fast, units can be added and removed, relatively insensitive to ground loops. Topology allows daisy-chaining..

There are some established Arduino network things as I recall.. I'll look..





44  Using Arduino / Project Guidance / Re: A new Project on: May 26, 2011, 02:39:07 pm
Hi rjb,

OK, you have a pretty good idea of the different parts or "subassemblies" of an autonomous "robot".

Try to get one working at a time, and then start putting them together.

Some Arduino basics are here: http://arduino-info.wikispaces.com/GettingStarted-Software

Some ideas and stuff here:  http://yourduino.com/how2start.htm

45  Using Arduino / Project Guidance / Re: Interactive Art Object Using Arduino+PIR sensors, which parts to buy? on: May 26, 2011, 02:31:44 pm
OK, So what I think I understand:

- You want motors to be able to act as a "winch" or "Crane", rolling a cable or string up, and rolling it back down again.

- So you need to be able to reverse the motors, right?

- You have some windshield wiper motors but you do not want to use the back-and-forth movement, and you will remove that part??

- You will have to attach some "drum" or "Spool" to wind the cable on.

- You need to know when the weight is at the top, and stop the motor.

- You need to know when the weight is at the bottom, and stop the motor. 

More questions:
?? How heavy is the weight
?? How long do you want it to take to go from bottom to top / back

OK, I see the Video and idea... 

- So the weight does not need to stop at the bottom??

Details!   That's what Engineering is about  smiley-grin
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