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Multiple output voltage regulator ? - SparkFun Electronics

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By chickenhawk
#198541
I don't if this is the right way to put this. I have a rover 5 with 2 motors with a FPV camera and a pan/tilt using two micro servos.
What I would like to do is replace all the following with 1 battery.
What I have right now is.

6- AA batteries - to motor driver to run the rover 5
1- 9 volt battery to power my Arduino
4- AA batteries to run the two servos
1- 3.7 volt lipo to run the FPV camera

Would it possible to have a larger battery and then have a multiple output voltage regulator ? I'm thinking about a lipo or a battery out of a RC truck?
By Valen
#198562
No, a voltage divider is not a regulator! It can be used to scale down a voltage. But when you apply a significant load to the middle between the resistors then it effectively adds a parallel resistor on the bottom. Then it's changes the scale down factor. No regulation at all.

You must uses proper linear or switchmode voltage regulators. The former 'burns' excess voltage away. The latter 'transforms' the excess voltage into extra current at the lower voltage and is more efficient for battery use.

In your case the Arduino UNO and motor-driver could be powered from the same 9-ish volt 6 AA battery pack. The motor driver usually does not need a fixed voltage, although it too will have it's limits. The Arduino has it's own linear voltage regulator and can easily handle the 9 volt, or even 12 volt. The others like the servo and the lipo/FPV camera will need their own voltage regulator down to their level. (you have not provided specifications so this is all guess work and expectations) All fed by the single large battery pack or each feeding the lower voltage in a cascade is possible.
By chickenhawk
#198569
What I have on hand is a 7.2 volt Nimh 5000 mah battery stick, out of a RC truck.
This is what I was thinking about:
Powering the Rover 5 motors and the Arduino board from the 7.2 volt 5000 mah Nimh battery.
And maybe using two adjustable Buck Converters, one to go from the 7.2 volt to 6 volts to run the two s90 micro servos and the other to go from the 7.2 volt battery to 3.7 volt for the PFV camera.
And maybe one more for future use?
Unless there is a smarter or better way.
By Valen
#198581
7.2 volt is barely enough for the barrel jack or Vin/Raw power input of the Arduino uno. Consider what happens when the motors draw significant current (voltage drops) or the battery is almost empty (7.2 volt is average level). The Arduino Uno voltage regulator may not be able to sustain the 5 volt and drop below it. The buck converters for the servo or FPV camera will probably adjust for it. But you don't want the brain of the robot to go into a temporary coma. Feeding the Arduino Uno with it's own 5 volt buck converter (bypassing the onboard linear regulator) might be a solution. But remember that switching voltage regulators do have more noise on the output. Sensors might suffer from that.