Hi,
Can I power up Arduino Uno R3 directly from car instalation (12V DC). Or shuould I use dedicated filtered power source which will provide me something about 5V DC.
You could use a 5V/6V cell phone car charger, but not directly to the 12V, it will be too much current. Plus your at the 12V input limit.
Ok thank you.
marcin_i:
shuould I use dedicated filtered power source which will provide me something about 5V DC.
It would be possible to power the onboard regulator directly from 12V but not advisable. You would be making the Arduino's voltage regulator dissipate a lot of voltage and this would severely restrict the amount of current it could provide without overheating. A typical car electrical system is also very noisy and this might be enough to cause problems on the Arduino. It would be far better to use an external regulator to output a nice smooth, regulated 5V and connect to the Arduino's 5V line. If it isn't capable of producing a well regulated and smoothed output then aim for a higher voltage (around 7V would be ideal) and supply it to the Arduino's Vin so that the Arduino's regulator just has to deal with a small voltage drop.
sorry the recommend limit 12v
PeterH:
marcin_i:
shuould I use dedicated filtered power source which will provide me something about 5V DC.It would be possible to power the onboard regulator directly from 12V but not advisable. You would be making the Arduino's voltage regulator dissipate a lot of voltage and this would severely restrict the amount of current it could provide without overheating. A typical car electrical system is also very noisy and this might be enough to cause problems on the Arduino. It would be far better to use an external regulator to output a nice smooth, regulated 5V and connect to the Arduino's 5V line. If it isn't capable of producing a well regulated and smoothed output then aim for a higher voltage (around 7V would be ideal) and supply it to the Arduino's Vin so that the Arduino's regulator just has to deal with a small voltage drop.
The same question comes up 10X per week. And different people have very different opinions.
I, for one, greatly disfavor "It would be far better to use an external regulator to output a
nice smooth, regulated 5V and connect to the Arduino's 5V line". It may work for some boards,
but not others.
If going to this trouble, I would rather use a 7808 [8V regulator] off the 12V line, and plug
its output into the Vin pin. Then, you're always safe.
Why would that not work for some boards? Are you thinking of 3.3V boards, or what?
Why would that not work for some boards? Are you thinking of 3.3V boards, or what?
Because I, for one, have seen nowheres in any v.reg datasheets where the manufacturuers
say it's ok to apply 5V to the "output" of the devices from an external source. Arduino is the
only place where I've ever seen anyone advocating such practice.
I've asked people to point out the relevant info in the manufacturer's d/s before, but no one
took me up on it.
Maybe it works ok for the boards and v.regs the developers used in past, because someone
tried it and the boards didn't fry, but who is guaranteeing it will work for every board? It's
your $65, after all, if using some of the newer faster Mega or 3rd party ARM boards.