Arduino Forum

Using Arduino => General Electronics => Topic started by: Akshaysarraf on Dec 20, 2013, 07:24 am

Title: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 07:24 am
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)
Title: Re: How to Power Arduino Externally ?
Post by: JimboZA on Dec 20, 2013, 07:37 am
You need to check that those adapters are "centre positive", assuming you have them plugged into the jack. Look here (http://en.wikipedia.org/wiki/Polarity_symbols) 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.

Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 07:47 am
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.
Title: Re: How to Power Arduino Externally ?
Post by: JimboZA on Dec 20, 2013, 07:49 am
Hmmm good point: one of those pics shows ac-ac, the other is dc.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 07:50 am
Ok Sir, I'll Buy a Multimeter and will Get back to you.... with My readings.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 07:51 am
Also look at the polarity on the connector (as JimboZA mentioned).

Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 03:08 pm
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!!

Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 03:19 pm
Check on the output of the regulator, it should be around 5V.
Which Arduino do you have?
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 04:44 pm
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 ?
Title: Re: How to Power Arduino Externally ?
Post by: JimboZA on Dec 20, 2013, 04:48 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 04:52 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:01 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:06 pm
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.


Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:11 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:15 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:20 pm
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.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:25 pm
Attached is the schematic for the PSU section of your Arduino.
Please check between each of the Test Points and ground.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:27 pm

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.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:32 pm
SIr, I am new at this. Electronics. Dont know much about Schematic Diagrams.

Can you suggest an alternate way ?
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:36 pm
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?

Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:47 pm
If it is the same board, check the voltages at each of the Test Point.
In all cases, black lead of meter to common ground.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:50 pm
Multimeter Redings, AC Voltage, Measuring across Output of My Power Adapter (Arduino NOT Connected)

22.3 when I Choose 200V as a Range on Multimeter
22 or 23 When I choose 750V as a Range on Multimeter

And Yes I have the same Board as shown by you
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 05:51 pm
OK then that power supply is not suitable.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 05:53 pm
Are you Sure about that ?

Do you still want me to take readings on TEST POINTS ?
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 06:11 pm
No need to take extra measurements as that is an AC power supply and not for Arduino use.
But keep the drawings I sent you so when you get another power supply, you can use it as a handy reference and also it will help you learn a bit more about how schematics relate to real world components.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 06:46 pm
Ok... Thanks a Lot.
Sir So which Power Adapter I Should Buy ?

Any Idea ?
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 06:53 pm
Don't throw out that power supply, once you get more practice with building things, you can add a bridge rectifier and a capacitor (perhaps a regulator too) and power small motors and such that will need around 24V DC.

As regards a power supply for your Arduino, get something that gives out around 9V DC @ 500mA or so but make sure it is regulated and that the voltage polarity on the connector matches that of the Arduino.

There are plenty available on the internet and many electronics stores will stock them as well.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 07:43 pm
Thanks a Lot for your Support Sir

Actually My Main AIM is... I want to Control my Room Lights with My Arduino... Reading some Online Tutorials.. I Bought an Arduino, Ethernet Shield and a 4 in 1 Relay Board (12V).

I noticed that when I connect Ethernet Shield and Relay Board and Run the Program...
I face 2 problems

1) My Ethernet Shield Gets Connected to my router for 10 Seconds and then gets Disconnects for 30 Seconds and then Gets back on for 10 seconds

2) My Relay makes a Buzzing Sound.

After Some Internet Research... I came to know, Both these Problems are because of More Voltage Consumption/Drop on Ethernet shield. My Laptop isn't enough to Power. So I started searching for External Power Supply.

Sir, Am I Going in right Direction ?
(I am a Newbie in all this)
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 20, 2013, 07:53 pm
It could very well be as the extra stuff you connected to your Arduino board will certainly consume more current and  you are powering it from the USB port which has a limit of around 500mA.

Without seeing your code and how you connected things, others will not be able to help you.
My suggestion is start a new thread under the "Networking, Protocols and Devices" section, post your code using the code tags plus an explanation of what you have tried thus far and any other relevant information.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 20, 2013, 07:55 pm
Ok Sir!
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 21, 2013, 06:07 am
Sir, I Tried to power my Arduino Externally with a 9V battery... as  adapters mentioned by you are not available in my area.
But Sir, my Board still doesn't start...

As asked by you earlier I measured AC voltage across the battery Ends (Arduino Not Connected), They are -

19 or 20 when Multimeter Range is 750V
19.7 when Multimeter Range is 200V

And DC Voltage across Battery Ends are 9.37 (Arduino Not Connected)

This is close to the ones i was getting through my adapter.
Title: Re: How to Power Arduino Externally ?
Post by: zoomkat on Dec 21, 2013, 07:34 am
Your old modem power supply should be ok for external power. I consider the arduino board power splitting between the external and USB power supplies as somewhat suspect. I have an old arduino that using an external 12v power supply connected to the barrel jack produced ~8v on the board 5v pin. I had to use a 7805 regulator chip connected between the 12v and the board 5v pin to get the arduino properly externally powered.
Title: Re: How to Power Arduino Externally ?
Post by: engr_junaid22 on Dec 21, 2013, 08:28 am
contact me i will teach you........ :P
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 21, 2013, 09:46 am
@zoomkat

I guess Arduino Duemilanove already have a  onboard 7805 Voltage Regulator Chip.

Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 10:00 am

Your old modem power supply should be ok for external power.

Did you forget that it's an AC power supply giving out 22V with no load?
Even rectifying and smoothing will be very close (if not over) the max input for the Arduino.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 10:02 am

@zoomkat
I guess Arduino Duemilanove already have a  onboard 7805 Voltage Regulator Chip.


Yes it has, but the more differential voltage it has across it, the quicker it will heat up plus you can't just go feeding it any voltage, it has a limit which is probably around 18V for light loads and dropping down to around 10V for heavy loads.
It's called de-rating.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 21, 2013, 11:47 am
Ok i get that..

So what do you suggest I must do now ?

As My Arduino isn't starting with a 9V Battery.
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 12:04 pm
You say your Arduino starts with USB power but not when you add the extra shields.
So why not power the Arduino with one USB port then get another USB lead, use only the red wire (+5V) and the black wire (GND) and connect the one end to another USB port and use that to power the Ethernet shield you mentioned?

First make sure that your Ethernet shield does run from 5V and not some other voltage like 3.3v, also make sure you separate any pin/s that the Ethernet shield is using to get it's 5V power from the Arduino as now it will be powered from the second USB port.
Lastly be careful as to not short the USB supply.

I still think it's easier to go buy a DC adaptor (9 - 12V) though.
Title: Re: How to Power Arduino Externally ?
Post by: zoomkat on Dec 21, 2013, 03:06 pm


Your old modem power supply should be ok for external power.

Did you forget that it's an AC power supply giving out 22V with no load?
Even rectifying and smoothing will be very close (if not over) the max input for the Arduino.


Your statement does not make much sense considering the below.

http://forum.arduino.cc/index.php?topic=205728.msg1514156#msg1514156
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 03:26 pm

Your statement does not make much sense


Have you forgotten that he also measured the same power supply with the DMM set to AC volts and got a reading of around 22V?
The DMM will give an erroneous reading on DC if one connects it to an AC source and since he got 10.5 V DC and 22V AC which one would you be more inclined to believe?

Let's assume that the PSU is giving out 22V AC, this is then fed to the Arduino where the input series diode will half wave rectify the AC and the puny capacitor after that will attempt to smooth it out but will not do a very good job as it's only a 100uF so the resulting voltage will be a partially smoothed DC with lots of ripple.
A great power supply that will make.
Title: Re: How to Power Arduino Externally ?
Post by: zoomkat on Dec 21, 2013, 03:56 pm
Quote
Have you forgotten that he also measured the same power supply with the DMM set to AC volts and got a reading of around 22V?


The data plate on the power supply is 220vac in and 9vdc out. In the photo his multimeter is on the appropriate settings and he gets an expected reading for a 9v wallwart.  I'll let you ponder the readings when the multimeter is not set appropriately.  ;)
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 04:01 pm

The data plate on the power supply is 220vac in and 9vdc out.

Really? why don't you have a closer look at the second photo where it says "AC -AC Adaptor".
It also says that it's a 9V 1A 9VA output, when last did you see the term VA being used for DC?

Quote

In the photo his multimeter is on the appropriate settings and he gets an expected reading for a 9v wallwart.  I'll let you ponder the readings when the multimeter is not set appropriately.  ;)

Exactly, it applies both ways.
Title: Re: How to Power Arduino Externally ?
Post by: zoomkat on Dec 21, 2013, 10:35 pm
Quote
Exactly, it applies both ways.


Maybe, maybe not. The D-Link adapter seems to be the adapter in question (the Beetel seems to be straight forward). I found an AC/AC adapter that has 7.5VAC output. Using an almost identical multimeter as the op is using, I checked the adapter output on the multimeter 200 ACV setting and I got 9v. I checked the adapter on the multimeter on the 20 DCV setting and got essentially 0.0v. This type of multimeter  (by design or not) does not seem to output a DC value when connected to a 60hz AC source. The op should be able to perform the same test with the D-Link adapter and confirm it has an AC output. 
Title: Re: How to Power Arduino Externally ?
Post by: UnoDueTre on Dec 21, 2013, 11:31 pm

Using an almost identical multimeter as the op is using......

Let's assume your meter and the OP's meter are the same, I find it quite strange then that he got a reading of 22V AC.
We can disagree ad nauseam but the fact remains that unless the OP has access to a scope and can post a screen shot, we ain't going to know for certain what that power supply is really giving out.
It could be AC, it could be DC it could even be that it's got a real crappy circuit in it and it gives out DC with loads of AC ripple.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 22, 2013, 12:16 pm
Images of my Output of AC Voltage reading of my BEETEL Power Adapter. Both Images are included having different Multimeter range.

Title: Re: How to Power Arduino Externally ?
Post by: zoomkat on Dec 22, 2013, 11:50 pm
You could try an experiment with a diode (which only allows current to flow thru it in one direction). Put the diode in series with the power supply with the meter set to DCV 20v. Try the diode in two different directions. If you get a voltage reading in one diode direction and 0v in the other direction, the power supply maybe DC. If the voltage readings are the same with the diode in either direction, the power supply may be AC.
Title: Re: How to Power Arduino Externally ?
Post by: Akshaysarraf on Dec 24, 2013, 06:25 pm
Thanks a Lot @Zoomkat and @UnoDueTre you guys are genius. You both helped me a lot.
this issue is solved. I used my Desktop and the circuit is running fine. My Laptop was supplying low voltage I guess.

I am having another issue, My Arduino hangs when I connect it with 220V supply. This question is not appropriate for this category. So here is its link.

Could you please help in this too.
http://forum.arduino.cc/index.php?topic=205825.msg1519182#msg1519182

Thanks a Lot!