Thanks for the advice! - I will test it out and update the circuits accordingly.

I did look at the circuit in my oscilloscope and noticed some pretty hefty voltage spikes.
- Probably a good idea to try to keep these down.

My high-voltage (tesla-freak) friend looked a bit concerned at my design too, so I will put in a few of his updates too.

I will submit an update when I have tested and written it. :-)

Kind regards
Christian Liljedahl

Hi

I am using an Arduino, Mosfet and ignition coil to make a spark plug spark.
- I have put together this little guide for others, who might need to control spark plugs.
http://christian.liljedahl.dk/guides/arduino-spark-plug

The setup works fine for me, but my electronics skills are not at guru-level.

Do anyone foresee any problems in the current setup? - I don't want to have a guide that misleads people 

Kind regards
Christian Liljedahl

Yet another very happy user, thanks a lot!

The fix - It works with Processing too, btw.

I am trying to get a link to this fix included in the
http://www.arduino.cc/en/Guide/Troubleshooting#toc14

.. I hope this will be possible. I remembered seeing this solution long time ago, but I had trouble refinding it.

More links to this genious :-)

with humble respect
Christian Liljedahl

At
http://www.arduino.cc/en/Guide/Troubleshooting#toc14

I would love to have a link to this thread included
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1237179908

.. since the above thread has the corrent answer and a solution to the problem.
(The problem is a defect rxtxserial.dll on windows.)

please include this - I don't know how to do the edit myself, I don't seem to have access to edit?

kind regards
Christian Liljedahl

[64.233.187.99 is not available anymore]

Regarding http://www.arduino.cc/en/Reference/Ethernet and all the client examples showing how to search google.

It seems like, that the address in the examples: 64.233.187.99  is not available anymore - at least not in Denmark.
There is no respons from the server - just timeout.
(Yes, I tried it in a browser too :-) )

Since this is a hello world example, it would be great to add to the example, that the google address might not be available, and that it is best to do a nslookup google.com on your computer, and put that address in the example. (Where I get 74.125.45.100 )

I would love to do the change myself, but it seems like the wiki is closed..?

Best regards
Christian Liljedahl

Hi there.

We have been working quite a bit with Arduino and Load Cells (strain gauges)
I have written a little guide to it here:
http://christian.liljedahl.dk/guides/arduino-and-load-cell
(Scroll down for the tech and the code)

Generally you need an amplifyer. We are using a little IC instrumentation amplifier, but you can do it with cheap opamps too.

kind regards
Christian Liljedahl

Force feedback with a resistor : Thats a great idea!  

- I got to think about posting at the exhibition group just a little to late, and then I was afraid to cross-post.

I have made a simple solution for a "rotation" sensor, to sense wich way a dial is spun, and how fast.
Using a DC motor connected between the 3.3V output on the Arduino board and the analog input.
Read the details here, and do comment on it, if you have any considerations :-)
http://christian.liljedahl.dk/guides/simple-rotary-encoder

regards
Christian Liljedahl

[Voltage: Don't overdo it.]

Thanks for the nice i2c example - good for getting started.

I have a few experiences with the LIS302DL that I think should be shared.

Voltage: Don't overdo it.
At first, I just send 5V from the arduino board to Vcc on the chip, as suggested in this article.
But I experienced the accelerometer randomly going dead.
Then I made a voltage devider with two 2k7 and gave it 2.5 v, and now it runs flawlessly.

Pull up - not needed?
I didn't bother to put pullup-resistors on the 4 and 5. It seems to be no problem to skip them.

Remeber - 4 and 5 is ANALOG pins
That i2c is on analog pin 4 and 5 is probably obvious, but it took me some time and frustration before I realized my error. Don't connect to 4 and 5 digital..

My few cents on this. Might post some code when the project moves on..

Best regards
Christian Liljedahl

Load Cell and Arduino connected using the ina125p ic.

I have just made a small project using this ic to interface to the analoginput of the Arduino board.
The ina125p is very very easy to work with, and can be used in many different configuration.
Just add one component: A resistor to set gain.

I have tryed to make a small page about the project:
http://cerulean.dk/words/?page_id=42

Good luck with yours. :-)

[50 days]

A thing to remember:

int has a range of -32,768 to 32,767.
32767 milliseconds = 32 seconds.

Meaning: After 32 seconds, your

Code:

lastTimeItHappened = millis()

will behave strange

ALLWAYS use the type long or even better unsigned long  when you work with millis() that way.

unsigned long has a range of 0 to 4,294,967,295  giving you
about 50 days of runtime before things get strange!

Good luck
C

This is a simple example I use:
Basicly the idea is:
- Use millis() to get the "time"
- Use a sin/cos function to determine the fade-level of the diode.
Benefit of using sinus is, that you get a much more smooth and pretty fade.
Linear fade is dull. :-)

Code:

int value, value2 ;
int ledpin = 10;                           // light connected to digital pin 10
int ledpin2 = 11;                           // light connected to digital pin 11
long time=0;

int periode = 2000;
int displace = 500;

void setup()
{
  // nothing for setup
}

void loop()
{
  time = millis();
  value = 128+127*cos(2*PI/periode*time);
  value2 = 128+127*cos(2*PI/periode*(displace-time));
  analogWrite(ledpin, value);           // sets the value (range from 0 to 255)
  analogWrite(ledpin2, value2);           // sets the value (range from 0 to 255)
}

I have heard about the xbee module, but was in doubt about it. Have heard ill about range and stability, but that might just be evil rumors?

I need to *transmit* data from each of the 6 arduinos and *receive* the data at a single point.

I have a project, with 6-10 arduino boards in different locations reading sensor data (accelerometer).
I want to collect these data as realtime as possible (within ms), and I want to do it wireless. With RF or .. something.

Maks transmitting distance is around 50 meters.
Each arduino board sample / transmit data at 400 hz

I could imagine one of the RF-modules could be used, but that is typically only 1 to 1. I need 6 to 1.

Do anyone have a good suggestion for a solution to this?

All the best
Christian Liljedahl

Hi
I have been trying to get a lego nxt ultrasonic sensor (rangefinder) to work with arduino, but have yet been unsuccessfull.
The US communicate with i2c, but it seems to not want to react to the commands i try to send to it with wire.
I have tried many many combinations, allso bitshifted.
But I have not been able to desichper what exactly it needs.

I can make my arduino work as a slave i2c-device connected to the nxt-brick and read out what it is sending.

But I fear, that somehow wire sends out "stuff" that the US does not like.

Have anyone successfully done this?

Best regards
Christian Liljedahl