I use a 12V power supply to power my arduino. Among other things I want to control some 12V hardware components (via a Darlington array). The peek power requirement will be around 6Watt. Can I just use the Vin pin to supply the hardware with 12V? Or can this pin only provide limited power? like all the other pins?
Can I just use the Vin pin to supply the hardware with 12V?
yes, if you look at the schematic you will see it goes through a diode first so it will not be quite 12V, but as 6W is 0.5A the diode should take it.
The previous reply makes no sense to me.
If you have 12V supply and some 12V circuitry, just power the arduino Vraw and the external circuitry from the 12v.
Don't even think about somehow routing the 12V via the arduino board at all, you can only get 5V out of the Arduino regulator and its not rated for 0.5A at 7V, since 3.5W will overheat it.
The previous reply makes no sense to me.
Actually the Arduino Vin pin can act as a external voltage source input to the Arduino board, or as a voltage output source to power external components.
Using the Vin pin as a output source the voltage will be .7vdc less then what is plugged into the Arduino external power connector, and be current limited by either the current rating of the external power source or the 1 amp series polarity protection diode on the Arduino board, whichever is less.
Either way, by way of the Arduiono external power plug or by wiring a external voltage source (of greater then around 7.5vdc) to the Vin pin, either will power the input to the Arduino on-board +5vdc voltage regulator to power the boards +5vdc components.
Lefty
I know I could just use the Vraw (directly from power supply) but this has some disadvantages in the setup I had in mind.
I had in mind to have a wire with plug going from the 12V Power supply into the power socket of the Arduino. The Arduino will be inside a neat control box that I designed together with all other electronics. This allows me to easily unplug the whole thing and have all electronics together in a nice little box.
If there is only the 1amp diode in the Vin pin I think I can just use that pin to pickup the input voltage (12V from the power supply) I put into the power socket (the small voltage drop is not such a big deal.)
I hope to get a clear conformation that this will work without blowing up the Arduino.
- edit
I thought it would be nice to let you know what it's for. It for an aquarium control system I'm building at the moment. (a lot of different lights, 3.3V LED, 12V LED 230V T5, feeding, temperature, water level, air pump, ect) The 12V I'm talking about will be for the 12V LED strips. Here is a picture of the control box.
the 1 amp series polarity protection diode
There appears to be consensus that this diode can handle 1 amp. In the Duemillanove Eagle files hoewever it is only specified as "diode" (no type or make). Does anyone know what component is actually used so we can look at the datasheet?
If it is all going to be inside a box, could you just hook up to Vraw by soldering to the barrel plug connector pins on the board?