Question: Powering the parts inside the arm.​

A project log for Building and improving the Thor+ robot arm

Building a 6-axis robot arm based on the AngelLM's Thor robot and the add-on's and improvements of dannyvandenheuvel.

SepioSepio 08/19/2017 at 15:550 Comments


I have to wait for some parts (among which the slip ring) before I can wire the PCB inside the arm. So I was thinking about the maximum amperage I need for all the parts inside the arm:

- 2x 5V fans  (2x 0.14A = 0.28A)

- Arduino Uno (0.1A)

- 6 Rotation sensors (0.1A)

- Servo (0.5 to 1 amp?)

- Ledring (24 NeoPixels at full brightness × 0.06A  = 1.4 Amps) 

I would also like to add a few MPU9250 9-AXIS Gyro Accelarator Magnometer Sensors in the future.

5V through slip ring.

The slip ring wires can handle 2A max. Danny uses one of the wires for 5V. This way it can handle 2A x 5V = 10W. I don' think this is enough.

24V through slip ring and 5V step down convertor on PCB

Wouldn't it be better to use 24V for this wire. This way it can handle 2A x 24V = 48W. I could convert it back to 5V on the PCB above the slip ring. This way I have 48W / 5V = 9.6A. 
The top of the PCB is cooled by the fan. So cooling isn't a problem. If I mount the PCB a little bit lower there is more than enough room for the step-down convertor.

This also means that if I hit the emergency switch in the power unit I only need to cut the 24V line. The 5V line can be left intact to power the Nextion display.


What do you think about this? Are there any disadvantages I didn't think about?