powering 35 servos

Projects General Guidance
1

I now have got 20 Hitec Hs-311 servo motors

I need 35 of them working in my project simultaneously running at fairly light loads

http://www.servocity.com/html/hs-311_standard.html
by the description above it says,

@ 4.7V
7.4mA AT STOPPED
160mA/60 degrees AT NO LOAD
700mA STALL CURRUNT

I have a SMPS that outputs 12V 4.2A and I'm currently powering them
with this, I connected 20 servos using the same datapin(PWM) from the Arduino
pin, using 7805 regulators to make 5V ( 10uF capacitor on the input pins ,
0.1uF on the output pins, 1 attatched for 1 servo ) then
I ran the Sweep sketch from the Arduino servo library examples
20 servos are working now
but after a few minutes 7805 will heat up so much that almost burnt my finger.
7805 has 1A output and 311 has 700mA running current so I thought It should
work fine but turns out quite unstable

so in order to run all 35 servos I think need a 5V switching power supply
there's plenty to choose but the problem is I do not want any fan noise
since this project is a sound related applicaion

I borrowed a 5V 240A MEANWELL power supply, It...... is..quite loud indeed
I won't be using this one

according to the Hs-311 specs I will need at least 35A current
12V 4.2A power is quiet and good, but it seems that 12V to 7805 regulator isn't a good idea,
5V 240A is too loud ,

is 5V 60A power will be loud ??
any suggestions please???

2

I would suggest you look into using a PC power supply modified for standalone operation. That should give you enough current capacity and they are pretty quite and very inexpensive if not free!

Lefty

3

I am still a novice at the electrical side of things (I'm a professional programmer), but I would imagine instead of having a single power supply for all 35 servos, you would want 3-4 power supplies for fewer motors (with common grounds of course).