Let's Make Robots!

Picaxe 28 and servo question.

Hi all :)

Im just getting started in robotics and just joined this forum. I got inspired by the great "start here" project you have here. I am starting with a similar project for my first robot, but I would like to make a few changes. Instead of using motors to drive the robot I plan on using servos modded for continuos rotation. The robot will have 4 servos. 2 for moving around, 1 for panning the head and the last one for either operating some sort of manipulator or panning the head up and down.

I have some questions though, which I hope you can help me with:

1) If I use 4 servos with the picaxe is it absolutely required that I run them of a different power supply? I would like to keep the size and weight down so Im reluctant to add an additional power supply.

2) How do I connect the servos to the picaxe starter board? Is it safe to connect all 4 through just the 330 ohm resistors like the head panning one on the starter robot is connected or is that overloading the board? Do I need to have the L293D Motor Driver or the darlington on the board at all if im just using the servos and no motors?

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1. I should think so, if the battery is able to deliver enough power. If you get problems with the processor resetting or hanging when using all 4 servos, I would consider using a separate power supply for the processor or using a larger battery.

2. Yes. Use resistors. Forget about the L293, it's for driving motors, which you don't have. Also, forget about the darlington driver, since you put the resistors, where it is normally placed.

Good luck