My Arduino Mega is getting extremely hot near the input voltage source and is a concern to me. I am using a 12VDC 2A source and need some power souring help. I am running a Ardumoto Driver Shield to run a strobe light and a 12VDC 1.8A submersible pump. I have split the power source into 2 output plugs to power the Arduino Mega and the Ardumoto separately. Should I use a voltage divider or some other voltage reduction going to the Mega?
Also, anytime the pump is actually hooked up and drawing power my GLCD screen starts getting really unstable and flashing odd numbers and letters, but only when the pump is actually drawing power.
Thanks, and if you need additional details, please ask.
This is for a fire alarm demo project for school, and dont know what to do at this point.
Normal when you’re trying to drive the Mega using 12V input. Read up on your linear regulators. The extra voltage/current/power is being dumped off as heat.
In this month’s (Dec. 2012) Circuit Cellar, Ed Nisley points out that almost all Arduino boards are poorly designed with respect to voltage regulators. Without any additional load on the ports, at > 8 volts input, they are usually operating at near maximum power dissipation.
Even having two LEDs driven by the port pins can overload some of the smaller boards. The regulator may temporarily shut down, leading to a “mysterious” cyclic power failure.
He recommends 7 volts as the maximum input voltage.
David V:
Should I use a voltage divider or some other voltage reduction going to the Mega?
David V:
I will drop the input voltage to 7 volts to the arduino.
I'll add the following only because of the 1st statement. A voltage divider won't act the same when current is being drawn from the divider as when it isn't. You might as well just put a resistor in series with the Arduino's supply line. What will happen though is the supply voltage (at the Arduino) will change as the current drawn by the Arduino changes. The Arduino's regulator will try to smooth out these changes, *as best as it can*, an produce a steady 5V for the '328 to run off of. If the Arduino's current draw doesn't change much, max to min, this "solution" can work but be aware that changing code can change the current draw. Also be aware to get a properly sized (power-wise) resistor. Just as an example, going from 12V to 7V while drawing an average of 200 mA means the resistor will dissipate (12-7)*0.2 = 1 watt (on average). That's a fair amount and more than your typical resistor can handle.