HI, Im using Arduino Mega 2560 board and with ethernet shield. and Im using 7809 regulator with 12volts 1.3Ah battery. but it seems to be not enough power. so I changed the regulator in to 7812 and use 2 batteries series. (24v) but my board is getting more heated. what should I choose as power supply ?? please help me.
The mega has internally a voltage regulator.Connect the power source in the on-board jack.My suggestion power voltage are 9V to prevent some heat problem.
The board has a 5V regulator. With a battery that can supply 1.3A.... what else is connected?
I use the ethernet shield with nog problems at all.
If you really want to make effective use of the battery, buy one of those 12->5V USB adapters (http://www.ebay.com/itm/1PC-DC-DC-Converter-Module-12V-To-5V-USB-Output-Power-Adapter-New-/310862144982?pt=LH_DefaultDomain_0&hash=item4860d3e5d6). Although the adapter can deliver 3A, there is a fuse on board to limit to 500mA over the USB.
That should be sufficient for the mega and the shield.
Raising the input voltage will only lead to more amps dissipated in to heat as you are transferring from 24V -> 5V. The difference is heat.
The board has a 5V regulator. With a battery that can supply 1.3A
No it can't - the reverse polarity protection diode is only rated for 1A.
CrossRoads:
The board has a 5V regulator. With a battery that can supply 1.3A
No it can't - the reverse polarity protection diode is only rated for 1A.
Yeah but that wasn't the problem... You can easily hang a huge power supply to the board. It will only draw as much as it needs. My KIM-1 used to hang on a power supply from a Control Data Tape Unit (+ and - 35A). The Kim only drew about 1A. No problem.
However if he were to reverse polarity then the diode will either short or die :).
My question was if he has so much power, what is he trying to run from the Mega. If it is only the shield then any normal battery that can supply 500mA should suffice as I run my ethernet shields connected to the USB and that has a 500mA fuse that does not trip.
thank you for replying me.
I have got wi fi router. its input is 5v 2A, so Im going to use separate 2 batteries in series (24v) with 7805 regulator. will it solve my problem ?
No - it will be worse! If you put 24V into a 5 regulator it will run really hot once you start drawing much current thru it. Even with 12V they tend to get pretty warm.
I'd go with a DC-DC converter as previously suggested. These efficiently convert higher voltages into lower voltages at high currents without wasting the voltage difference as heat.
As an example, look at the 2nd item in this list
moek0000:
so Im going to use separate 2 batteries in series (24v) with 7805 regulator. will it solve my problem ?
No! The bigger the difference between the regulator's Input voltage and Output voltage, the hotter it will run!