Regulator Heating

I have a little question.I am working on a project that will work 24 hours per the day.I notice that the Arduino regulator is heated .Is this heat is a dangerous issue i should think about(how to know that this heat is upnormal level).Are there any solutions.
(I am using a 7.3v 1A wall adapter cause i am using a GSM\GPRS shield+module on the Arduino) Many thanks.

There is an effective upper limit of 500 mA that is imposed by the Arduino's regulator. If it is really uncomfortable to touch (Temp > 85C/125F) you are drawing too much current from the board. My recommendation is to use a separate PSU preferably a switcher to power everything except the Arduino and tie the grounds together in a star topology to reduce errors due to ground currents. I do here when I work with my several Arduino's. I've added a picture of a bare board, header to a shield via a cable and a Power supply on the left side of the picture in the background you can see an Uno, the shield, cable and header in an Uno box I bought from Amazon. The Box is great for protecting the Arduino from stray stuff (crap) on my desk and bench. The Power supply (small PCB on the left of the breadboard in the picture) plugs into the breadboard and will supply 3V3 or 5V to either rail or both at the same time, I bought it on Ebay. Liudr sells the cable shield through Dipmicro or Inmojo. All work really well or as well as any breadboard does.

Doc

{Edit, Doc}

Docedison:
There is an effective upper limit of 500 mA that is imposed by the Arduino's regulator. If it is really uncomfortable to touch (Temp > 85C/125F) you are drawing too much current from the board. My recommendation is to use a separate PSU preferably a switcher to power everything except the Arduino and tie the grounds together in a star topology to reduce errors due to ground currents. I do here when I work with my several Arduino's. I've added a picture of a bare board, header to a shield via a cable and a Power supply on the left side of the picture in the background you can see an Uno, the shield, cable and header in an Uno box I bought from Amazon. The Box is great for protecting the Arduino from stray stuff (crap) on my desk and bench. The Power supply board plugs into the breadboard and will supply 3V3 or 5V to either rail or both at the same time, I bought it on Ebay. Liudr sells the cable shield through Dipmicro or Inmojo. All work really well or as well as any breadboard does.

Doc

Why do you recommend a switching power supply? Just efficiency? I've been told by "reliable" sources that linear is almost always better than switching at everything other than efficiency.

Easier to make linear power supply but it wastes more power to heat.

No that isn't really the case, Switchers are troublesome when it comes to noise especially the Mains type switchers however a small choke and a couple of good 10 to 47 uF caps will contain that rather nicely. the other thing to consider is that all the little ones based on the LM2596/75-6 type devices operate at 50 Khz and many if not all of the new ones operate at considerably higher frequencies 150 KHz to 1 - 2 Mhz is common now. This is considerably higher than the Arduino is "Likely" to be able to detect and produces little interaction. All four of the devices I own have noise levels < 100 mV at 5V DC out. The Final point is if you can reduce your power supply demands you can reduce your power supply size or increase the available load current by the gain in efficiency. There is also another point here and that is simply to power the non critical heavy current loads from the switcher. Your information was very correct 15 20 years ago but times have changed considerably. I'm about as "Old School" as anyone around but with an understanding of the devices and their applications they are great tools. Linears? yeah sure... for critical low noise LOW CURRENT applications only and even then I personally would try one and very carefully analyze it before discarding the idea... They'res just too much to win by choosing a switcher.
IMO

Doc
{Edit, Doc}

.Is this heat is a dangerous issue i should think about(how to know that this heat is upnormal level).Are there any solutions.
(I am using a 7.3v 1A wall adapter cause i am using a GSM\GPRS shield+module on the Arduino) Many thanks.

I have a rather tight requirement when it comes to v.reg heating. If you cannot
hold a baby's little pinky to the surface of the device without the baby crying,
then it's too darn hot [this is theoretical only - don't try at home!].

There are several solutions.

  1. those Arduino bds with the dinky little smt v.regs are really marginal designs, when
    it comes to loading and overheating. SOT-223 packages are especially prone to over
    heating. You might look for a bd with a larger v.reg package, like TO-220, or at
    least a D-Pak. Just because the v.reg says 1A or 0.5A, that's current not heat.

  2. try a 6V wallwart instead of 7.3V. Those devices have 4-5V extra coming out with
    small loading, and the voltage only drops to the rated value with full load as specc'ed.

Good idea, most of the newer warts are switchers (the light ones) and as such are well regulated. 85C isn't very hot... it's the temperature of my hot water and should be considered a limit (the Mfr's do) not an operating point...

Doc

Also factor into the topic that most linear voltage regulators have automatic internal protection and will shutoff if either the heat gets too high or the output current is in excess of the cut-off protection circuit. So while heat is never a desired property unless that is the purpose of the application, I think many overstate the possible damage that a Arduino board can or will suffer from it's voltage regulator. I ran my first arduino (RS232 serial clone version) board from a regulated +15vdc laptop power brick and while the on-board 7805 regulator did run pretty hot, it never failed or caused a problem that I could see.

I too have changed my thinking on voltage regulators after seeing the wide selection and low prices of buck and boost type switching regulator modules on E-bay from Asian sellers. Up to 2-3 amps output they have just too many advantages over older linear 1-3 amp regulators, at least in my opinion. And don't forget the $1 5.1vdc @1 amp 'cell phone charger modules' I find at thrift stores all the time. They are perfect for lots of smaller standalone arduino projects.

Lefty

Many thanks everyone i 'm sorry for this late reply.I want to clear that
1-I have to work with a wall adapter cause i have no experience in working with power supply so i want a solution with wall adapter(or a declaration tells me how to replace the wall adapter with power supply to work as i mentioned 24/7).
2- I want to use this shield with it's module ( GSM GPS shield for Arduino - Open Electronics - Open Electronics )it's working with input voltage between 7.5V and 12V.
but when i attach the shield with my uno it's get heated(but if i use the uno with the same volt and ampere it's working in a normal heat)
The main problem (i couldn't understand ) why the manufacturer said that the input voltage to the arduino should be between 7.5V and 12V while the arduino regulator allow only 5v to get to the arduino which supply the shield.
3-I want to know the exact name of the regulator used in uno.(and does it have internal protection or in some cases my uno may be damaged and damages the shield).
I want to say thanks again for everyone here.

The part of the Arduino data sheet that Clearly you didn't read is the part about recommended loads for the Arduino board or any of the recommendations here.
Or about the shield you are using.
Try to remember that ALL of us here that answer these questions are just people and that we had to find your answers the same way you should.
You might also search the forum for your shield too as it's power requirements are likely addressed as well including solutions to what is a VERY common issue that I tried to address for you with the few small suggestions I made.
I am not really trying to be a hard case about this BUT You have to do part of the work your self.
Did you know that you can search this forum for answers and that the search will return a value for relevancy?
If you Search for "regulator heating" in about 20 seconds you will get 5 pages of answers.
Read them and follow the idea's and suggestions there as well as any links or other information.
If you still have unanswered questions then come back and ask them...
I am reasonably sure you will find the answers you seek long before you need to ask for them here again.
I am also sure that there will be other questions to be answered as well
Again search and then if you found no useful answer...
Please come and ask to see if someone has a solution.
You will never learn if you ask first and read second.
All you will learn is how to ask...
What if one day there is no one to ask?. What then will YOU DO?.

Doc

Thanks for your advice.I want to illustrate that i am new to the electronic and arduino world.

I am very aware of that Sir... I wasn't trying in any means or manner to talk down to you in any respect.
It's just that If you choose to use an Arduino there are some few things you will need to know in order to properly formulate a question that is answerable.
Thus my suggestions about trying to find answers before you ask us the questions we would probably have to search in the same manner as I suggested You to do...
Once you've read the available material and IF you don't find the answer... You might know enough more to ask the correct question.
At least you will know MORE than you did before and IMO that's a really good thing...
BeCause... You just never know where any knowledge learned...
Might be applicable. IMO

Doc