My arduino gets hot when us a 12 volt adapter

i have it on a 6 volt adapter right now but i would like to us a 12 volt adapter, but it gets hot when i do. all my cams are on 12 volt and im running servos for pan and tilt and it woks good but i don’t like having to us and 6 and and 12 volt adapter to power it all ( trying to keep the cords to a min) is this normal for the arduino to get hot? or do you think this is something wrong with my wiring? all i did was splice into the 12 volt to bring power to the arduino. I dont want to just run my arduino hot so may be there is a way to lower the volts? in new at all this and only really lured about the arduino to run servos. but im having lots of fun the more i lurn.
Thank you for your help ;D

Yes it will get hot with 12 volts, the voltage difference 12 - 5 = 7V is across the regulator and with say 200mA of current that gives :-
0.2 * 7 = 1.4 Watts of power to burn off.

So there is nothing wrong with your setup.

I had a similar situation where I wanted a 12V source. I went to my local “thrift store” and found a car adapter that reduced 12V to 9V. I removed the jackets from it, and ran the 12V into it and used the 9V for the Arduino power jack. Everything runs much cooler.

Thank you for getting back to me so quick. I was thinking (after reading what you both said) what about using some sort of resister. If you think this will work what kind should i use?

Although you can use a resistor it is not a good idea. This is because the voltage it will drop is dependent on the current and as this fluctuates so will the voltage drop. This causes noise on the supply which can lead to malfunctioning of the circuit. This is ironed out to some extent by the voltage regulator but it is not a “nice” solution and I would never do it myself.

http://cgi.ebay.com/ebaymotors/Reducer-for-Heater-Defroster-Switches-12-Volt-to-6-Volt_W0QQcmdZViewItemQQ_trkparmsZ66Q3a2Q7c65Q3a15Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem2554bc383fQQitemZ160335411263QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessoriesQQsalenotsupported

so this will not work for me?

even the arduino it self has somthing on it that dose this, how else would it take a 12 volt and do 5 volt out puts, all i need is something like that.

No, it won’t. Its for reducing a voltage across a heavy fixed load (defroster). It will have practically no effect on the milliamps the arduino board uses.

what if i found a 12 volt adapter with lower milliamps would the arduino still get hot

also had this thought what if i put a little heat sink on the part of the arduino that is getting hot, and just run it with the 12 volts. would it over heat and fry?

A quick dirty method is to wire say 6 - 1 amp silicon rectifier diodes in series and pass the feed to the arduino through it. Each will drop the voltage by about 0.6 V. 12 - 3.6 = 8.4 volts. Should work nicely.

Suitable diode would be the very common and cheap 1N4004.

1 amp silicon rectifier diodes
http://cgi.ebay.com/25-1N4004-SILICON-RECTIFIER-DIODE-1-AMP-400-VOLTS_W0QQitemZ360020917204QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53d2eb3bd4&_trksid=p3286.m20.l1116

so us 6 of these in a row and that should do it? all so dose it mater wich way the face?

They would do fine. Wire 6 nose to tail (band all at one end) The banded sides go towards the arduino. It won’t do any harm the wrong way, it just won’t work.

so using 6 will work but is there bigger ones that i could just use 3 to 2 or even 1? just want to ask before i do a buy it now on ebay is this they way to go?

If your “12v” supply is unregulated, it could be kicking out nearer 15 V, you can adjust the number of diodes to get around 8V at the arduino.

No, bigger ones will have a similar voltage drop so you’d still need the same number. 1 AMP is plenty.

ok then im going to buy them and ill try it out a maybe take some pics and post them.
Thank you so much

There are more elegant solutions using say a 7812 voltage regulator and a zenor diode to hold ground around 4 volts high, but the rectifier diodes are easier to understand. :wink:

http://cgi.ebay.com/100-pcs-1N4004-1A-400V-Diode_W0QQitemZ250395339396QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a4cb9aa84&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A15|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

found this lots cheaper will they work?

Same thing - the 1N4004 , you’ll be able to build lots and lots with a hundred of 'em.

They might take a while coming from Thailand though.

Remember this does not eliminate the heat generated it just distributes it around the other components. To remove the wasted energy you need to go to a switching regulator.