3 servos at the same time, LEDs in series and power

Other Hardware General Electronics
1

Hi,
I am trying to figure out some power issues: i have 3 servos (needing 4,8-6 V), around 25 LEDs (20mA, 3,2 and 1.9 forward V) and 4-5 pressure sensors with variable resistance hooked up to an Arduino Mega…
I use an external power supply for the Arduino board, but after a couple of minutes of running the 3 servos simultaneously they stop running (in MaxMSP they are still sliding, so that's why we are guessing that it is a power issue).
Is it okay to use an external power supply directly connected to the board and set it higher - like 6 V? Or should we use an external battery pack of 6-7,2 V only hooked up to the servos…?
Also i am in doubt about if i could hook up our LEDs (20mA, 3,2 V) in series...the 1,9 V LEDs work fine in series and 5V according to http://led.linear1.org/led.wiz, but the others need higher V, which we do not have now...

Any suggestions would be helpful.

thanks
edit

2

hi,

Read these two posts on my blog -

this should answer most of your questions, come back with any you still have

Duane B

rcarduino.blogspot.com

3

All servos can be controlled....

4

I use an external power supply for the Arduino board,

You also need to use an external power supply like below for the servos. Don't try to power the the servos from the arduino.