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1  Forum 2005-2010 (read only) / Troubleshooting / Re: stand alone Atmel168 on: November 27, 2008, 12:58:04 am
And once you have your Atmel programed with your sketch you will probably want one of these boards to save some time with hand wiring a prototype.

I have several of them and they work great.

2  Forum 2005-2010 (read only) / Troubleshooting / Re: Power source for arduino diecimila on: August 20, 2008, 09:56:30 pm
Is your 12v 1.2A supply regulated?  if not it may be putting out some ware around 16 volts with a light current load on it.  I would try to scrape up something in the 8 to 9 volt range.  that would reduce the voltage drop across the regulator and lower the power dissipation.  Ideally you want to put only 3 to 4 volts more into the regulator than the 5 volts that you want to get out in order to keep that un-heatsinked regulator cool.  In a perfect world, you would get yourself a LDO "Low drop out" regulator and connect a 6 volt supply,  that regulator will run "too cool for school".

3  Forum 2005-2010 (read only) / Development / Re: Arduino Battery Life? on: November 13, 2008, 10:42:45 pm
You need to know the total current requirement to figure that out.
My Arduino draws about 25 mA while running just about any code that doesn't light any LED's.

An Energizer 9V alkaline battery is rated at 600 mAh or "mili-amp hours" with a 25 miliamp load - so 600 / 25 gets you about 24 hours.  One problem though is that they rate their battery at 600 mAh down to 4.8 volts.  The Arduino regulator will stop putting 5 volts out once the battery drops below 7 volts so you should probably cut that 24 hour calculation in half.

when needing to run from batteries, I run my Arduino from a 6 AA cell battery holder which has a typical 9V battery clip type connector on the end,  I fill it with 6 NiMH batteries.  Arduino circuits are a little power hungry for a little 9V alkaline.

4  Forum 2005-2010 (read only) / Development / Re: Getting a near naked ATMega to run? on: November 13, 2008, 10:24:05 pm
Are you familiar with the Arduino Runtime Board from NKC electronics.

Its only $3.99, not much more expensive than a Radio-Shack proto board and will save you a lot of time.

5  Forum 2005-2010 (read only) / Interfacing / Re: MaxSerial Diecimila spontaneous reset problem on: August 20, 2008, 07:56:13 pm
Did you try a simple 4.7K pull-up resistor on the reset line?  that way it would take at least 1 mA to cause a reset,  your 150 foot wire may be less of an antenna with a little termination.

6  Forum 2005-2010 (read only) / Exhibition / Re: Car Keypad on: May 13, 2009, 01:05:40 am
Nice and clean prototype work,  First class job.
Keep on building,
make stuff.

7  Forum 2005-2010 (read only) / Exhibition / Re: Arduino Support high Amps?? on: October 15, 2008, 07:18:05 pm
Hold everything, that schematic will make a mess of your Arduino.  The full current will be sinked by the Digital IO pins.  Those BLACK wires you show connecting the cathodes of the LED's will have the same current trhough them as the RED wires sourceing the LED's.  You want a simple transistor switch to sink the LED cathodes to GND.

Someone posted a similar question in another section.

check out the first reply on that page.

8  Forum 2005-2010 (read only) / News / Burn the Bootloader without an AVRISP on: November 11, 2008, 08:21:16 pm
This clever little trick is new news to me, sorry if I'm wasting space with something everyone already knows about.

If you don't already know how to burn the Diecimila bootloader without the AVRISP or similar clone; then you really need to watch this cool demonstration.

the only hardware mod requires placing a 4 pin header in the X3 connector position on the PCB and then making a simple cable.

9  Forum 2005-2010 (read only) / News / ATmega328P  -  New from Atmel on: September 02, 2008, 09:10:22 pm
Twice the FLASH memory and only $3.70 at Mouser.  People have already tested boot-loaders for this new device.  I would imagine that all Arduino boards will be shipping with this chip soon since it looks like it will add no more than $0.34 to the board cost of those buying them in Qty. 100.

The 28 pin PDIP that all us Arduino hackers will want to plug into our old boards will be marked ATMEGA328P-PU.  Digi-Key lists them as "no stock" and Mouser lists them as "on order" at the moment,  its a rather new chip but they should be easy to come by very soon.  Boot-loader testing that I mentioned was done by a few lucky folk who received factory samples.

Atmel decided that only a 20MHz version of this chip will be made, no 10MHz version is planned, that's why they dropped the speed rating from the part number "-PU" and not "-20PU"

10  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: External 5V power question on: November 17, 2008, 10:23:45 pm
You will find that a lot of wall wart type power supplies which are rated for high current will be over by a few hundred millivolts to compensate for cable loss. With a 3 amp load, even .2 ohms in the wire will have your 5 volt supply down to 4.4 volts at the connector end of the cable.

You can expect most wall wart supplies that are rated over one amp to be on the high side of their rated voltage output.

Does anyone else find it ironic that Arduino fails the spell check in this Forum  smiley-wink

11  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Beginner topic - type of wire for motion projects? on: November 17, 2008, 10:39:30 pm
If you go to and type "hookup wire" in their search engine and limit the search to 24 AWG stranded wire you will find a lot of suitable and easy to work with wire.  there probably are a lot of less expensive sources if you search long enough.

Find yourself 4 100 foot roles of 24 guage stranded hookup wire in 4 different colors and you will have a ten year supply for any low current hobby projects.


12  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Can Arduino exucute a program without connected? on: November 17, 2008, 10:09:57 pm
All you need is something like this little adapter.

And maybe one of these since Alkaline 9V batteries don't last very long with the 25 mA load of the Arduino PCB.  Fill this baby up with 6 AA rechargeable NiMH batteries and save yourself all kinds of money,

You may find this cable handy as well.

This is the 2.1 x 5.5 mm barrel power connector that most of the Arduino boards use.  I'm sure there is a less expensive source someware but I haven't found one yet.  this is a top quality connector made my Switchcraft.

Good luck and have fun.

13  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Where to Start? on: November 15, 2008, 12:43:17 am
The Arduino Programming Notebook is a good way to start.
It has many example schematics for interfacing and such as well as programming help.


14  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Total novice here... on: October 24, 2008, 03:27:41 pm
If you open the project files in Eagle capture/layout, you simply select Run from the File menu "in the schematic, not Layout window" and run bom.ulp.  A nice little bill of materials will apear that you can save as a TXT file.  Hint:  view and print the file with wordpad rather than notepad or you'll lose the nice formatting.

the free version of Eagle will work for this as well.

15  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: TIP102 vs TIP120? on: August 20, 2008, 08:43:57 pm
Also, do you really need a Darlington transistor? any relay that requires less than 200 mA can be driven with an ordinary GP "general purpose" NPN like a 2N2222 or a 2N4401.  look for the Hfe specification on the transistor data sheet.  Hfe is the DC current gain.  A transistor with a minimum Hfe of 80 will draw less than 2.5 mA from the pin of the micro controller while driving a relay coil that needs 200 mA to close.  The TIP102 has a  minimum Hfe of over 1000 and would close a relay that required over 2 amps without drawing 2 mA from the micro controller pin.
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