I been working on a small project at home. I have a mobile robot with 2 servos operating the wheels and 6 others operating an arm, making it a total of 8 servos. I'm currently using Arduino Mega and an external power supply, a modified ATX power supply (5V 30A). I have a battery from a previous R/C car project, 7.2V 4500mAh. I would like to use this battery to power the robot. I've tried connecting it directly but the servos do not switch on. I get a big voltage drop and current drop, as many of you figured out already. I thought if I made a simple voltage follower it would work, but didn't. How else can I power these servos without buying a Servo Controller. I would like to make a circuit with parts that can easily be found locally. Any help that can be offered, would be great.
How else can I power these servos without buying a Servo Controller.
A servo controller really doesn't play into powering servos. servos are usually powered from the battery +- leads with the ground wires all connected together.
Are your servos rated for 7.2v operation? Many are not. If not, you will need some type of voltage regulator.
I power 18 servos off of a higher voltage battery and use a voltage regulator from http://www.dimensionengineering.com/
I got the SWADJ3, which lets me cut select the output voltage, and it handles enough current for my needs.
Vince, I like what you did with the voltage regulator. But can you give me a list of the parts you used, the voltage regulator, battery, and the small circuit board switch(what does this do? do I need it?). Also, the pictures are great but are a bit fuzzy to see the connections in detail. Could you give me a quick short summary how you connected these devices.
This is a power switch that replaces a mechanical switch.
Small breadboard
Various headers #1065#966#965
Power block #830
Although this comes out of the bread board fairly easily.
I also got wire kits #313 Elenco JW-350 350-Piece Wire Kit
Dimension Engineering
Voltage regulator http://www.dimensionengineering.com/DE-SWADJ3.htm
They have many different models to choose from, with widely ranging capacities. This model works for my 18 servos - 12 are standard sized analog, and 6 are standard sized digital.