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16  Using Arduino / General Electronics / Re: 0-5 v into 0-2.5 volts ? on: April 27, 2012, 03:21:47 pm
I would use a pot of say 50K ohms.  The run the voltage through the pot and the wiper will be the voltage out.  It is the same as a voltage divider circuit but uses the wiper to make two resistors, one on each side of the wiper.

Something like this:
   -0  |  0-

the circles are the terminals to the pot and the | is the wiper.  This is a general solution that can be used whenever you need to get less voltage then you have. 

Use your VOM to see what the voltage is on the wiper and you are done.  If you want to check it you can then test the resistance between each terminal and the wiper.  And, with nothing up my sleeve, I predict that you will find that the ratio is the same as what the voltage divider formula predicted.
17  Using Arduino / General Electronics / Re: What do you make of this??? on: April 26, 2012, 07:25:50 pm
I'm cool with the pluto thing but I thought, there I go thinking again, that tantalum and electrolytic caps used the arc and straight line symbol and other caps used two straight line symbol.  That is what has me wondering. Here we have and arc and straight line with no polarity.  I can throw a 0.47 cap in and see what happens.  I'm sure nothing will self destruct but I have never seen this symbol for a non-electrolytic cap before.
18  Using Arduino / General Electronics / What do you make of this??? on: April 26, 2012, 05:15:41 pm
I am working on building a circuit that I found on line.  Here is a link to a GIF of the schematic.

Take a look at C1.  It looks like it would be an electrolytic cap, or a tantalum, but I have no idea what 0.05 would be.  There is no listing for a 0.05 tantalum cap on digikey  and an electrolytic capacitor doesn't get close to 0.05 anything.  So what do you all think this cap would be?

19  Using Arduino / General Electronics / Re: Seeking an alternative to transistor on: April 26, 2012, 05:01:20 pm
You could use relays.  I just ordered some from futurlec. Here is a link to the ones they have:

They have 5 volts relays that you can drive direct from the pins on the arduino.  Make sure that you don't draw more current then the arduino will source, check the data sheet and use ohms law if you didn't know that.  Or get a ruggedduino and it will put out 500ma per pin!

20  Using Arduino / General Electronics / Re: Soldering options for this part on: April 26, 2012, 04:34:10 pm
I just bought a rework station, delivered for $62.  But I haven't used it yet.  I have used an electric skillet to do SMD work.  Here are a couple of links to tutorials.

If you search Ebay you can find rework stations cheap.  The one I got is a W.E.P. 858D.  Dave Jones did a review of this model on his EEVBlog.  He liked it and he showed how it works on a couple of different items. 

So you can go to your local hardware/housewares store and get a $20 skillet or order a $62 rework station. Or you can do both and have all your bases covered.

I used the skillet method to solder some SMD Hall Effect sensors and, after I got a decent skillet, it worked just fine.  I first tried it with a real cheap and small skillet.  It was barely big enough to made a toasted cheese sandwich in.  But it just didn't get hot enough.  But when I bought a larger skillet it worked fine. 
21  Using Arduino / Installation & Troubleshooting / Re: Arduino IDE 1.0 On Linux Mint 12 on: April 09, 2012, 03:22:36 pm
It looks like the problem is with this line in the "arduino" launch script:

APPDIR="$(dirname -- $(readlink -f -- "${0}") )"

This is supposed to figure out what directory the arduino software is in, even if the "arduino" script is a symbolic link.  It looks like readlink isn't returning something that dirname can handle.  Anyone have an idea of how to change it?  I'd suggest posting follow-ups on the Google Code issue list ( so they don't get lost.

This is not where the problem is.  It's easy to see just do an echo $APPDIR > <somefilename> and see what you get.  I got the correct directory so I know that is not the problem but I still have the error.  But if you look at the very last part of the very last line you find .  This is what is causing the error. 

But why?  If you look at this line of the script:
export PATH="${APPDIR}/java/bin:${PATH}"
and you  found out what APPDIR is using echo $APPDIR > <somefilename> you will find that java doesn't exist under APPDIR.  So the first part of the PATH is incorrect but the second finds java.  But the java it finds knows nothing about  So it throws the error.

The ${APPDIR}/java/bin is the directory structure of processing not arduino so go figure.
22  Using Arduino / Installation & Troubleshooting / Re: Arduino IDE 1.0 On Linux Mint 12 on: April 09, 2012, 02:57:50 pm
If you do a google search you will find this problem goes all the way back to version 18!  I am sure it is in the arduino package but seems to be fixed in the git repository.  I could not run arduino 1.0 under Mint but I could under Debian. (I had recently changed my OS.) But when I installed processing it ran fine.  This told me that java wasn't the problem.  There are lots of posts on this error about making sure java is installed correctly and making sure classpath is correct and reinstalling the AVR tool chain.  These are all dead ends.

I didn't pour over the change log but building from git is easy and it gives one the latest version.  In my opinion it would be a waste of time to try and fix an existing version that has this error. Just build it new and you are good to go. And once you do that it is very easy to keep up to date with the latest version.

But if one wants to reinvent the wheel go for it.
23  Using Arduino / Installation & Troubleshooting / Re: Arduino IDE 1.0 On Linux Mint 12 on: April 09, 2012, 06:54:26 am
I got it to work!!  But I needed to build Arduino from git.  I followed these instructions:
It's a small pain but if you follow the instructions it should work.

I made the mistake of building it as root.  Then I needed to change ownerships and permissions but that's not hard.  I then wrote a very small script to have something to start arduino without having to do all the cd to build and run ant.  It now works fine.

Go for it, it's easy.

Oh but now it's not in the mint database of programs so you have to build it from git if you want to upgrade it some day.  I am putting the web page in the directory so I have a copy on hand at all times.

Told you I would post how to get it to work smiley-cool  smiley-lol  smiley-cool  smiley-grin
24  Using Arduino / Installation & Troubleshooting / Re: Arduino IDE 1.0 On Linux Mint 12 on: April 07, 2012, 09:30:41 pm
I can't fix it but I didn't want you to feel alone.  I also am using mint 12 and have the exact same problem.  It's not a java problem. it's a processing problem.  See this part "processing/app/Base"  But I can run processing just fine, go figure.  If I can get this to work I will post how I did it.  And maybe you could do the same.

25  Using Arduino / LEDs and Multiplexing / Re: LED very dim on: March 19, 2012, 10:03:28 pm
Yes I just figured that out myself.  The pin had no declaration of output or input. OOPS well I guess everybody has memory problems when they get older. smiley-mr-green smiley-mr-green

I saw a MRI of my chest.  My lungs have big long sections that are calcified, probably damaged when I had acid fumes almost kill me.  I suspect my brain looks similar. 
26  Using Arduino / LEDs and Multiplexing / Re: LED very dim on: March 19, 2012, 09:10:04 pm
I just tried using an ardweeny that was running the blink program on pin 13 and the LED lit up just fine.  I am stumped.

I just rewrote the sketch to use pin 5 instead of pin 13.  Had the same problem of a dim LED.  I switched it back to pin 13 and it was bright.

Why is that happening?
27  Using Arduino / LEDs and Multiplexing / LED very dim on: March 19, 2012, 08:47:45 pm
Hello all.  I have a problem I just don't understand. I have been working with my son.  We started with the blink program.  I had been showing him circuits using the 5 volt rail and the ground, no control from the controller at all.  Then we set up to have the blink program.  When the pin goes high the led  goes on but is very dim.  Dim to the point that all you see is a small dot of light in the LED.  I tried using another LED same problem.  I tried using a different arduino but still no joy.  I put a VOM across the output pin and ground and got 4.89 volts, close enough.  So that tells me that the arduino is not supplying enough current to the output pin.  I have no idea why.  The 3.3 volts and the 5 volts of the arduino lights up the LED just fine, almost blinds me, but the pins don't.  I tried different pins as well but no joy. I also tried all three ground pins as well.  I have no idea what's going on.  I have done this a lot, who hasn’t, and it always lit up the LED brightly.  I would say that the board has a problem but I used two different boards and they both did the same thing. Does anybody have an idea what is happening? 
28  Using Arduino / Programming Questions / Re: How do you send data to arduino using the serial monitor? on: February 27, 2012, 01:23:35 am
I suggest that you take a look at this example:

Hopefully it will be what you are looking for.
29  Using Arduino / Installation & Troubleshooting / Re: Error on compile -stdlib.h not found on: February 24, 2012, 07:48:19 pm
I am on a Linux system . Puppy Linux 5.3 in fact
Arduino is installed in my home directory but as I am root it matters not.
My problem is with "stdlib.h"
How does your post help me if thats what you intended?
I just wonder if you read my posts at all before posting your reply?

I have/had the same problem.  And actually johnwasser gave the correct answer that helped me solve the problem.

I am using Lubuntu 11.10 and because of John's answer I looked if there was something not installed for the avr compilation system.  And hey guess what there was.  I found it in Synaptic avr-libc was not installed.  I installed it and all was right with the world.

And tytower I suggest you find a way to deal with your stress a little better.  Everybody that answered was trying to help you.  Just as I am now.
30  Using Arduino / General Electronics / Re: Help !!! Smart GPU Questions on: February 05, 2012, 07:08:25 pm
DIY nail guns that barely shoot i'm mostly ok with.  Its web forum posters in control of 100000 lb moving at 80 mph that really freak me out.  Please pull over and get some coffee and your internet fix!

Actually he never said he was doing any of this while driving.  You just assumed that.  So what makes you think he is putting anybody at risk??  It's my not so humble opinion that you owe this gentleman an apology.
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