I have been feeding the ARduino 2560 a regulated 12 VDc power supply, but i am concerned that ther is quite a bit of heat coming off the voltage regulater on the main board, all the literature states any input from 5 VDC to 20VDC but i think i may be introducing product failure with 12 VDC shoudl i step it down to 9 VDC?
i have notcied that if i use a 5VDc input there is not enough power to trip the external 5 VDC relays that i use with the device
any thoughts about using a 12 VDc regualted supply
i have notcied that if i use a 5VDc input there is not enough power to trip the external 5 VDC relays that i use with the device
That's strange... It shouldn't matter where the 5V to the relays is coming from. Is there something else you are powering, possibly pulling too much current and causing the 5V to drop? Or, are you driving many relays?
With a 9V supply, the power/head dissipated by the regulator will be almost cut in half... You'll be dropping 4V across the regulator instead of 7V (with the same current). In case you don't know, power is calculated as voltage x current.
all the literature states any input from 5 VDC to 20VDC
It gets a little "fuzzy" when you add circuitry and draw additional current. If you are powering the Arduino alone, I guess you can go up to 20V.
The 5V pin is not a 5V input pin ! It is an 5V output pin, and so is the 3V3 a output pin.
The voltage regulator will not blow, it will lower the voltage to prevent overheating.
I have a switching regulator with a few selectable voltages. So I set it at 7.5V and it works perfect.
However, my Arduino Mega is running with power at the 5V pin, so I do use the 5V pin as input. I have a unregulated DC voltage (7 to 23 Volts) with a DC-DC converter to make 5V. That is connected to the 5V pin. The voltage regulator could blow because of the reverse voltage, so I have a diode to protect the voltage regulator. So I have lots of power and the power part stays cool.
The 5V pin is not a 5V input pin ! It is an 5V output pin,
Confusing message as you then correctly describe how to feed power into the board via 5V pin.
(diode from 5V (anode) to Vin (cathode) to avoid reverse driving the regulator).