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1  Using Arduino / Displays / Re: 2.2" TFT Module for Arduino from dx.com on: Today at 03:54:45 am
If you have connected a 3.3 volt board to a 5 volt supply you may have already caused irreparable damage, especially if it was connected long enough to get hot.
2  Using Arduino / Programming Questions / Re: interfacing sim 900 with atmega328 without using gsm shield on: Today at 03:27:15 am
SIM900 requires a supply voltage of 3.4V - 4.5V. I wouldn't recommend 5 volts.
3  Using Arduino / General Electronics / Re: Novice needs Help for GPS and GSM shields on: September 16, 2014, 03:57:56 pm
Try looking for a shield based on the SIM908. It is combined GPS &  GSM/GPRS. However, I personally have no experience of the device...
4  Using Arduino / General Electronics / Re: What I can do with this breadboard shield? (Apprentice) on: September 16, 2014, 08:18:12 am
It's been discussed before:

http://forum.arduino.cc/index.php/topic,154992.0.html
5  Using Arduino / Programming Questions / Re: Sending an SMS through GSM without serial monitor on: September 16, 2014, 02:42:04 am
The code I posted above works. Uno R3, official Arduino GSM/GPRS shield.
6  Using Arduino / Networking, Protocols, and Devices / Re: sending SMS via gprs unit on: September 15, 2014, 03:57:07 pm
Yes. It's the same as sending an SMS from your phone. Ok, a little more complicated as the phone makes it easy for you, but yes, you can send a text to anywhere in the world. And at the risk of being pedantic, it's the GSM standard you would use, not GPRS, which is internet connection.
7  Using Arduino / Programming Questions / Re: motor with romeo all in one on: September 15, 2014, 03:06:47 pm
Holmes4, you need to put the closing bracket at the end of the URL.

8  Using Arduino / Programming Questions / Re: Sending an SMS through GSM without serial monitor on: September 15, 2014, 12:40:45 pm
Code:
#include <GSM.h>

GSM gsmAccess;
GSM_SMS sms;


void setup()
{
  char remoteNumber[20] = "+447751123456";
  char message[100] = "Hello!";
 
  Serial.begin(9600);
 
  bool notConnected=true;
 
  while(notConnected)
  {
    if(gsmAccess.begin("")==GSM_READY)
      notConnected = false;
    else
    {
      Serial.println("Not connected");
      delay(1000);
    }
  }
  Serial.println("Connected!");
 
  sms.beginSMS(remoteNumber);
  sms.print(message);
  sms.endSMS();
}

void loop()
{
}
9  Using Arduino / Programming Questions / Re: Crash debugging - RAM dump on: September 15, 2014, 08:34:46 am
If the cause is caused by the software 'locking up' (entering an infinite loop), then I came across this:

http://www.megunolink.com/how-to-detect-lockups-using-the-arduino-watchdog/

I've not tried it and obviously it requires an understanding of assembler.
10  Using Arduino / Programming Questions / Re: Sending an SMS through GSM without serial monitor on: September 14, 2014, 02:49:53 pm
You might want to try prefixing your number with the international dialing code for your country rather than 0.
11  Using Arduino / Project Guidance / Re: RFID triangulation feasability on: September 14, 2014, 05:27:12 am
I'll be the first to admit that I don't know a great deal about RFID cards and readers, but my understanding is that the reader will detect a card when it is in close proximity and read (and write) any information stored on that card. When it is out of range (depending on the frequency they operate on, ~100mm) it cannot detect the card.

This seems completely at odds with the scheme you are proposing, which is why I asked.
12  Using Arduino / Project Guidance / Re: RFID triangulation on: September 14, 2014, 04:37:42 am
Just to be clear, could you provide a link to the RFID cards and readers you are contemplating using?
13  Using Arduino / General Electronics / Re: 5v relay on a nano. Why isn't it switching on: September 12, 2014, 12:44:32 pm
Looks like it's going to the base of the transistor to me?
14  Using Arduino / General Electronics / Re: 5v relay on a nano. Why isn't it switching on: September 12, 2014, 10:18:27 am
Your drawing is still wrong. The right hand connection to the relay wants to go to +5v.

A general purpose transistor for playing around with is the 2N2222 which at a glance Maplin don't seem to stock, so you might want to consider eBay? I would suggest Rapid Online, but you need to assemble a fair sized order to get free delivery!

Failing that, the 2N3904 looks fine for the job. Minimum gain of 100 (from the Maplin site) so for 80mA you'll be drawing .8mA from the Nano pin. 200mA max, 40 volts, all within spec.
15  Using Arduino / General Electronics / Re: 5v relay on a nano. Why isn't it switching on: September 12, 2014, 08:56:25 am
The diode does go in parallel with the relay, but the negative end towards positive. This is to deal with the brief burst of energy created when the relay is turned off. Not having it risks damaging the transistor.
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