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196  Forum 2005-2010 (read only) / Exhibition / Re: Paint on the TV screen with Arduino on: April 20, 2007, 11:05:37 am
Can you briefly explain how you did it in English? I don't speak French at all!


197  Forum 2005-2010 (read only) / News / Re: Importing SparkFun products in the UK on: March 02, 2008, 10:57:33 pm
Breakout boards, wireless stuff, micro controllers, MMC/SD Card stuff, GPS, LEDs, actually, how about EVERYTHING? The cool thing about Sparkfun is that they have all sorts of stuff at reasonable prices. The problem is if I wanted to get a couple chips and LEDs for $5, I'll need to fork out $10 for shipping and wait two weeks. An UK reseller will be great!

198  Forum 2005-2010 (read only) / News / Re: avr tutorial on: December 05, 2007, 08:43:11 pm
Hey, really nice work, I have a friend that might be interested in getting an arduino, this will save me time explaining things! I liked how you explained the differences between byte, int, long and stuff, showing that you get weird results from not using the proper types. I had to help out in a micro-controller lab at uni, I saw a lot of people getting stuck after multiplying a int by a large number, totally messing up the program even though the equations were correct!

Oh how do I apply for a contract job at "Blinky Lite Fun Company Inc"  smiley-grin? I can totally make things blink!

199  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: isn't the arduino a development platform on: November 25, 2009, 04:49:43 pm
The RBBB is the way to go. I bought an arduino NG board years ago, back when it still used atmega8. Since then I've bought nearly a dozen RBBBs, they are great for small enclosures and things that fly like my helicopter.
200  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Posting reply with image on: January 13, 2009, 09:19:34 pm
You can try google pages. It's for websites, but I simply use it as a storage place of all my images I need to link to forums, you get 100MB free, obviously more if you sign up for more accounts...

201  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: My Arduino is a mouse?! on: January 07, 2009, 03:43:31 pm
OK, found it.

Go to regedit,


Find entry "Start", set value to HEX 3 (manual) or 4 (disabled). Restart.
202  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: My Arduino is a mouse?! on: January 07, 2009, 03:21:00 pm
I had similar problems before. I think Windows has some legacy RS232 mouse driver that automatically activate when certain serial baud rate is used. Can't remember how I got rid of it now... Have you looked in device manager and see if there's new mouse detected? Maybe try disabling it?
203  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: arduino or basic stamp on: February 18, 2008, 02:48:51 pm
(Shameless plug) For an arduino based roving robot project:

I also have a BS2, but since I got the arduino, I don't use it any more. Arduino is much more powerful (analog in, hardware serial, hardware PWM, 1k ram, 16k flash),  I mean, arduino has 1 kilo byte of RAM, the BS2 only has 26bytes, and only 4k flash memory! But the BS is much better documented.

204  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Generating Composite Video on: May 25, 2007, 10:29:11 pm

Just want to say good luck! I hope you'll find a way to get it to work eventually, meanwhile I can dream about arduino pong!

205  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 19, 2007, 10:46:22 am
OK, here's a picture:

Does it look correct? I used a 470 Ohm 1% for Rgain, so the total gain should be (1+2*R1/Rgain)*R3/R2 = 4270. I haven't checked if that's true, since I don't have anything that can measure in the mV range the sensor outputs.

What would have helped me would be a tutorial on how to do proper data acquisition. When I get all my stuff working, I'll write up something about amplifiers and A2Ds, but I'm going to need some help, since I don't know much about either!

206  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 17, 2007, 07:34:21 pm

Yeah, I've actually got an AD623 (a instrumentation Op-Amp) sample on the way which I'll use in the final design, and the LM324 will probably be used as a general amp for other stuff that comes along.


Do you want me to write something general about Op-Amps? I don't feel confident enough to actually teach other people what to do with Op-Amps. I feel like I know just enough to be dangerous. I guess I'll do a write up on how to interface with the MPX2102 pressure sensor, and kind of skimp over the Op-Amp stuff. I wish I knew how to use Eagle to make cool diagrams and such!


207  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 10, 2007, 07:48:11 am
Ok, a couple 1% 100k and 10k resistors plus some caps later, I have a working instrumentation amplifier with gain control! There is some offset error, but I can get rid of that by changing the pot on the bridge. Now I can measure pressure differences of less than 0.5m in altitude (it's better than that but there's a bit of noise because I'm over-sampling the A2D). If I need to improve the performance later, I'll probably get a better chip, or buy a instrumentation amplifier IC. Now all I need to do is figure out why my wireless mouse is interfering with the readings.

This has been really helpful, thanks everyone!


Edit: Hey 0008 is out!
208  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 07, 2007, 11:56:06 am
Thanks everyone for your help!

Sorry I'm not making this clear. What I meant was that since I was trying to build a Instrumentation Amplifier, which involves 3 OpAmps (using 3 out of 4 from LM324) connected via resistors, like this one from wikipedia:

From what I know, if I want to reduce the common mode gain and offset errors, the resistors R1's, R2's and R3's should be exactly the same. I don't have a electronics shop, I only have a couple resistors of each value, so trying them one by one is not really an ideal solution. I guess I can use pots, but that'll add 3 pots to the design, plus the one already on the Wheatstone bridge! Buying some 1% resistors may be the best solution.

I get the feeling that I'm following the book too much, trying to build a perfect amplifier. A little less CMRR may not matter in the end at all, since it's not like I'm building a precision instrument.


209  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: June 05, 2007, 03:00:39 pm
Just an update, I've bought a LM324, and got it working in 15 min. Although I think gain of 1000 might be to high, now its so sensitive that I can't even tough the sensor!

Got another question though, what do you do to get resistors to match?

210  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Frequently-Used OpAmps? on: May 28, 2007, 10:47:54 pm
Actually, now I think about it, maybe I'm just complaining too much. The AD7792 has all sorts of settings that let you change the gain, update rate, bias currents and so on that I don't really need to touch, but I just "had to" mess with them because they were there to be messed with! That's what made the code really long. I think if I just left everything in default, it'll be just much simpler. What I was hoping for is a way to get data with something as simple as analogRead(), without adding a large amount of code. Obviously, that's not realistic with external components, and I'm asking for too much. It's a really good quality chip though, almost no noise at 16bit with a gain of 128.

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