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91  Forum 2005-2010 (read only) / Frequently-Asked Questions / Homebrew H-Bridge possibly with pyrotechnics :-) on: March 03, 2010, 11:49:41 pm
I thought I could wire up my own H-Bridge based on info I found in Internet, so instead of getting an SN754410, I bought four TIP120 darlington transistors.
http://www.fairchildsemi.com/ds/TI/TIP122.pdf
http://focus.ti.com/lit/ds/symlink/sn754410.pdf


http://en.wikipedia.org/wiki/File:H_bridge_operating.svg

Based on the info from Wikipedia, I've wired up my transistors like this.  To keep it simple, I represented each darlington pair as one transistor. D9 and D10 are Arduino Digital Pins 9 and 10.



I think it should work, but... when I turn on the Arduino, BEFORE I upload my sketch, who knows what pin 9 and 10 output would be?!  What if they were both set to HIGH?!
I probably would see some impressive pyrotechnics when I short + and - together with those transistors, right?!

Obviously, I could add a NOT gate, and control one transistor pair with pin 9 and the other pair with the inverted pin 9.  Is that my only option?

It's so easy to accidentally set pin 9 and 10 to high, so maybe I should abandon this and get the SN754410 instead.  Your thoughts?
92  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Best place to get breadboards online? on: February 28, 2010, 04:03:43 pm
I'd like to update you guys on my breadboard purchase.

http://g33k.blogspot.com/2010/02/breadboard-customization-i-asked.html

Thanks for all the suggestions!


93  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Best place to get breadboards online? on: February 18, 2010, 12:48:10 am
Thank you all for telling me not only the good ones to get but also the ones to avoid.  The problem with online shopping is that I usually order things that I wasn't planning on getting to "save" on shipping. :-)

PS: TchnclFl, your post is hillarious!  ;D
94  Forum 2005-2010 (read only) / Frequently-Asked Questions / Best place to get breadboards online? on: February 17, 2010, 09:02:26 pm
I'm thinking of purchasing 4 or 5 separate breadboards with +/- rails so I can combine them if I want to or keep them separate for different projects.

eBay is the obvious answer, but with so many low quality products out there, I was wondering if you guys can share your own actual purchase experience.  Good product for a good price.  Thank you in advance.

PS: I am located in the U.S.

95  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Servos vs DC Motors? on: March 14, 2010, 08:06:25 pm
Quote
Is there a forum favorite site to get servos from?
I do not speak for the forum, but I have been pleased with these $2.77 Mini servos from hobbypartz.

http://www.hobbypartz.com/topromisesg9.html

They're probably not as accurate nor as powerful as the more expensive or larger models, but they good enough for
my use.



96  Forum 2005-2010 (read only) / Frequently-Asked Questions / Making my own Arduino USB cable on: March 13, 2010, 06:57:02 pm


I recently made my own Arduino USB cable.  

This is kinda chicken and egg thing.  If you're a n00b, you want to save money and make your own cable, but at the same time, if you're a n00b, you probably don't have the multi-tester needed to ensure that you do not damage your computer or Arduino.

Proceed at your own risk.  :-/

http://g33k.blogspot.com/2010/03/making-my-own-arduino-usb-cable-i-dont.html
97  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: First Arduino + Servos, what to buy? on: March 01, 2010, 02:01:34 am
I didn't see a portable power source for your robot.  smiley

Maybe you want to get one of these to power the Arduino using a 9V battery.
http://www.sparkfun.com/commerce/product_info.php?products_id=9518

You may also want to get a separate battery holder to power the motors (maybe you can power them using rechargable batteries).
http://www.sparkfun.com/commerce/advanced_search_result.php?keywords=battery+holder&x=0&y=0&search_section=products

Sounds like a cool project, please keep us posted here.


98  Forum 2005-2010 (read only) / Frequently-Asked Questions / How to choose an LED on: January 29, 2010, 02:48:48 am
Hello,
74HC595 seems to be a popular way to drive LEDs, so I'm going to get a few of those at Jameco.  However, I'm overwhelmed at the vast selection of LEDs.  How do I know which ones are suitable to be driven directly by the 74HC595 ? Thanks!
99  Forum 2005-2010 (read only) / Bar Sport / Re: POST YOUR WORKBENCH on: March 25, 2010, 01:41:47 am
This is my actual "work" bench, where I work as a software developer.  
During the day Arduino stuff lives in plastic drawers underneath the table.  At night... Arduino comes up and play. :-)

Descriptions and another photo at Flickr.

100  Forum 2005-2010 (read only) / Bar Sport / Re: ethernet modules on: April 03, 2010, 10:04:04 pm
westfw,
Thank you for the detailed and concise description of the different devices.
Is there a wiki page listing the different ways to network an Arduino?
What's the policy for creating a new wiki page at arduino.cc?

It would be nice to have one page where everyone can go to see the pros and cons of different Arduino networking options.  For instance, has anyone worked with a SitePlayer before?

[edit]I don't have any Ethernet devices for my Arduino yet, so I've been trying to learn about them also.  Here are two product reviews I've found to be informative:


[/edit]
101  Forum 2005-2010 (read only) / Bar Sport / Re: Arduino documentary on Brazil TV program... on: March 21, 2010, 09:13:35 pm
Radamés,
That's very cool!
Thanks for sharing and translating.
102  Forum 2005-2010 (read only) / Bar Sport / Resistance is futile on: March 05, 2010, 02:02:29 pm
I'm sure some of you have seen this site before, but it made me LOL, and it's Friday here in the US.  Have a great weekend everyone!

http://thereifixedit.com/2010/02/20/epic-kludge-photo-resistance-is-futile/

http://thereifixedit.com/2010/03/01/epic-kludge-photo-granddad-was-serious/
103  Forum 2005-2010 (read only) / Uno Punto Zero / Re: Sort out that darn Shift-Backspace on: April 01, 2010, 11:06:26 pm
salsaman,
The problem is that it is very easy to accidentally hit backspace while still holding shift  key for previous character(s).

BTW, on the Macs, you can do a forward delete in any application by pressing the delete key while holding down the fn key.
104  Forum 2005-2010 (read only) / Uno Punto Zero / Suggestion: Add COM port selection in toolbar on: March 17, 2010, 07:22:59 pm
In addition to Tools > Serial Port > ComX, it would be nice if the current COM port is shown in the toolbar.  Clicking it would show a menu to select a different COM port.

By coincidence, the right most icon is Serial Monitor, so putting it to the left of that icon makes sense. :-)
105  Forum 2005-2010 (read only) / Uno Punto Zero / Feature request: No selection means whole line on: February 15, 2010, 03:57:05 pm
This is a feature that I use all the time in Microsoft Visual Studio (VS).

If you do a Ctrl-X and there is no text selected, VS would cut the entire line wherever the insertion caret happens to be (it does not need to be at beginning of end of line).

This is really handy for cleaning up extra blank lines, ie: Ctrl-X, Ctrl-X.

or duplicating/moving a whole line up/down, ie:  Ctrl-C, down arrow, down arrow, Ctrl-V
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