i newly got myself an arduino but i dont want to connect it to my pc with usb every single time. i found a DC/AC adaptor and its 13W my arduino is the uno R3,
You actually have a AC/DC converter. AC to DC. Read the label. DO you also see the O/P or output listed on the label? What does it say? I can't make out the fuzzy image.
Here are the UNO specs re input voltage
so yes it's ok as long as the DC out is less than 20V, but I like to stick to 12V
If the power brick is old, with a relatively heavy transformer inside, then don't use it.
Unloaded voltage of those ones can be 50% higher than what's written on the label.
12volt on the DC socket is getting in the danger zone, especially when you connect power-hungry sensors to the Uno.
Voltage limit of an Uno R3 clone is 16volt, because of the 16volt electrolytic caps fitted.
An official Uno R3 is AFAIK using 25volt caps.
Much safer for the Uno to use a 5volt cellphone charger, connected to the USB socket.
Leo..
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This! My own observation using an Arduino Uno R3 or an Arduino Mega is powering with external 12 VDC the regulator gets toasty, not fire breathing snap, crackel, pop but warm and thats less any load on the Arduino boards. Heed the words of WaWa above,
Ron
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everything you said is correct, its an old AC/DC adaptor and its heavy as a brick. Also its an arduino uno r3 clone
Hi, @supermariofan42
It is hard to read in your images, what are the I/P and O/P ratings written on the unit?
Thanks.. Tom... 
Unless you can actually test the open circuit voltage with a meter I'd not use it.
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um, its an 12v İ/O (my bad i read 13V) and it has both of 13V and 12V so,
İ/P : AC 230V 50Hz 13W
O/P : DC 12V 500mA
Buy new glasses - there's "13W" (Watts, input) and "12V" (Volts, output)
Still - it's not good for much in this regard - the modest Arduino on-board supply fed by a lame source. Nevertheless, if it's not regulated it will load down right away. If you don't have a voltmeter then forget it.
okay, its time to forget it i guess? Cause i don't have a voltmeter
That would be my advice. Or better still get a voltmeter, they arent expensive - cheaper than a pint of beer.
i actually used the AC/DC thing and it worked fine, only thing is the LED's were brighter more than then they were on USB? and also it was a bit smelly
Fail
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Side by side comparison DC/USB
also i cleaned my nose and did a test again after leaving the uno open with the AC/DC for a while. No smell.
nothing has gone wrong after weeks, it works perfectly fine even with the ac dc adapter being used for a long time, it looks fine i think its safe
Until it is not...
As pointed out, it may be operating on or over the very limit of the caps and regulator...
Electronics tend to withstand some mild abuse for an unpredictable amount of time...
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What was a bit smelly?
Get hold of a multimeter and measure the voltage from the plug pack.
You need to measure your circuit to see if everything is within spec.
Tom....
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