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Topic: Single Voltage supply for Arduino and Servos (Read 294 times) previous topic - next topic

cyberjeff

I have a little arduino uno project that requires small servos and motors.

I'm confused about how the Arduino draws and regulates power. I thought I could just run run the Arduino off 6V (4 AA) and that would give the servos 6V, however this does not work. The 5V pin looks like 4.3V (I thought it should run at that,but no).

So, when the Arduino runs off USB power, is the 5V regulator out of the circuit? 

Arduino recommends,a minimum of 7V, but this is more than the MG90s servos are rated. And it would be more like 9V (6 AA) or 7.5V which is (5 AA).

So, I have a low voltage drop LM2940, and I have good electronic skills, how do I power this up?

Jeff

Grumpy_Mike

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So, when the Arduino runs off USB power, is the 5V regulator out of the circuit? 

Yes.
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I thought I could just run run the Arduino off 6V (4 AA) and that would give the servos 6V, however this does not work.

Yes it won't.

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So, I have a low voltage drop LM2940, and I have good electronic skills, how do I power this up?

The LM2940 requires at least 0.5V so you should be fine using that to feed the output into the 5V pin and power the servos off 6V.

zoomkat

If you want to experiment, you probably could directly power the arduino from the 6v batterys thru a diode to drop the voltage to ~5.3v (I doubt 5.3v will damage the arduino, and the battery voltage will be dropping due to useage) , and use a big capacitor down stream of the diode to protect the arduino power from voltage dips. I've done a similar setup below for another servo chip.


Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

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