How to Power Arduino Externally ?

I looked a few links, but couldn’t understand.

I tried doing it using a Power Adapter from my Old Modem, (I used Adapters of 9V 1A and 12V 500mA)

But It doesn’t work. Neither any of the LED is glowing nor my Sketch is Starting.

But it works fine when I try to power it using a USB cable and connecting it to my laptop. What to do ? Please Suggest.

NOTE - I read it in some links, they says to measure the Voltage Readings across Vin and GND Pins of arduino. I don’t have any devices to measure Voltage or Current.

I’ve tried these both adapters… Still not working

(I’ve Attached Both Images. Please Check)

You need to check that those adapters are “centre positive”, assuming you have them plugged into the jack. Look here to see the symbols if you are not familiar with them. Edit: the polarity symbol should be “somewhere” on the adapter- I’m surprised it’s not in the view you posted, but it ought to be somewhere.

Do those adapters actually work ?

PS… you definitely need a multi-meter to do any Arduino work, it’s very difficult if not impossible to diagnose problems and check connections otherwise.

Be very careful with modem power supplies as many of them output AC (at 9 to 12V) as opposed to DC which is what you want.
Look at the supply/adaptor and check for symbols as per the attached pic.

AC_DC.jpg

Hmmm good point: one of those pics shows ac-ac, the other is dc.

Ok Sir, I'll Buy a Multimeter and will Get back to you.... with My readings.

Also look at the polarity on the connector (as JimboZA mentioned).

DC_pol.jpg

I Bought a Multimeter and measured the Voltage output of my Adapter. It turns out to be 10.58

Now After Connecting it to my Arduino I Measure the Voltage across GND and Vin it also comes the same.
Still My Arduino doesn’t start.

Please Help!!

Check on the output of the regulator, it should be around 5V.
Which Arduino do you have?

Voltage across Voltage Regulator is 4.77
I have a Basic Arduino with ATMEGA328 chip. (also known as Arduino Duemilanove, I guess).
Sir, What to do next ? So that I can turn it ON using my Adapter ?

Sounds to me that if you get the voltage you put in out at Vin, and you're also getting 5v out where you should be, the Arduino is damaged somewhere or other.

Did you measure the voltage between the regulators output and ground or across the regulator (input and output)?
The correct way is to measure between the regulators output and ground.

Once you have confirmed that the polarity is correct and that you have around 5V on the output of the regulator, then quickly switch on.
I'm not familiar with the Duemilanove, but I'm guessing that it also has a power on led.
Check to see that the led comes on, if it does great, then measure again on the output of the regulator to make sure the voltage has not dropped.

If the led does not come on, immediately disconnect the power.
Either way, please report back.

Earlier I checked across INPUT and OUTPUT of Voltage Regulator. It was 4.77
Now, I Checked across COMMON and OUTPUT it is coming 5.12
And My arduino has a POWER LED, It Turns on when I use My USB Cable along with my LAPTOP to power.

OK , those voltages look good.
Have you loaded a simple sketch onto the Arduino like Blink? (this will allow you to quickly determine if it's working with the new power supply).
Now disconnect the USB cable and try to connect the power supply, looking at the power led and the Blinking led.

Sir, It already had a loaded Sketch, everything runs fine When I Power with USB Cable. But as soon as I Use Power Adapter it doesn't starts. Not Even the Power LED turns on.

Try to have the multimeter connected at a point on the power supply and quickly measure as you turn the Arduino on.
Please ensure that you are measuring the output of the power supply.
Report back the voltage that you get.

Sir are you asking me to Check the Voltage Across the Positive and Negative Ends of My Power Supply ?
Sir, I did that... In the photo of Multimeter above... I was using the Multimeter directly to the Power Supply...
If You'll look closely in the photo you can see me doing that.

Attached is the schematic for the PSU section of your Arduino.
Please check between each of the Test Points and ground.

Akshaysarraf:
Sir are you asking me to Check the Voltage Across the Positive and Negative Ends of My Power Supply ?
Sir, I did that... In the photo of Multimeter above... I was using the Multimeter directly to the Power Supply...
If You'll look closely in the photo you can see me doing that.

Yes, I understand, but have you checked it with the Arduino connected?
I have posted a schematic with different points to check.

SIr, I am new at this. Electronics. Dont know much about Schematic Diagrams.

Can you suggest an alternate way ?

OK, let’s try something else.
Put your meter onto AC volts (not DC) and measure directly across the output of the power supply (Arduino not connected).

Another thing, is the attached picture the same as your Arduino?

ArduinoDuemilanove.jpg