My First Robot: Eve

You should read up on the new Dynamixel Property servos.they are not round but have inline body and shafts configuration.. Go to Robitis.com. Theven servos might interest you for your project.

One solution to the problem of pulling so many amps and needing to buy a "super" power supply is to run your robot off several smaller power supplies. Don't tie them together in series to boost the amp capacity because that won't work. You will have one or two hog the load. When running several ps's on the same robot you need to run them in parallel and manually distribute your load among them. For example run one set of arm servos off one PS and the other arm of a second. Then you can have a third PS dedicated to other devices like audio. This also helps with electronic noise. If your audio is picking up the whine of servos or motors moving or the click of transistors turning on and off lights you can run them on different PS's. Just don't tie the DC side nutrials or grounds together because this noise runs on the nutrials.

Dave, if you aren't tying the grounds together, do you need a seperate EZ-B (or other controller) for each power supply as well? I thought you needed to tie the grounds of the servos (or h-bridges) to the EZ-B as a signal reference.

That might be a good idea for a large robot anyway, basically set up each group of movements as independent subsystems, but does add to the project complexity.

Alan

Ya, Alan, grounds and neutrals are hard to figure out sometimes. tired There are time when separating grounds are a good idea. I'm sure you've heard of ground loops. eek These can turn into a nightmare. Then, some devices require shared grounds so they operate together like the EZB ans other micro controller and the motor controllers they operate. Then with other devices, if you tie the grounds together you do end up transmitting electronic noise to places where it's not welcomed. Electronic noise will be apparent right away in an audio system. I'm sure most have heard it clicking or humming away in the background of a sound track or music. Here you would want to isolate your sound system from the device causing the noise if possible. Feedback devices also suffer from noise and may affect your controller because it will transmit less accurate info. With these devices you may end up adding extra grounding to bleed off the noise. Wiring electrical circuits to power electronics is tricky and requires forethought, planning and maybe even some trial and error. eyeroll There's never an easy answer is there? LOL

Why do little toy servo motors need hundreds of amps? The wall socket only gives me ten amps and I'm running an industrial fridge, 2 3D printers, a projector, a 4K tv, a kettle, an air conditioner and all the lights in the house. Something seems majorly wrong here. How many amps does a car use? A car would definitely defeat my robot in a game of tug of war.

My original idea to keep the arms light was to have a bank of servos in the torso and run bicycle cables pulling against springs. Has anyone done this?