Hello, I decided to make a robot which can avoid obstacles in his way, now I have a 4xAA block and I will try to use it as my main&only power supply, will this be enough for 2 servos (Tower Pro SG 5010), Ultrasonic sensor HC-SR04 and an Arduino Pro mini V2?
That battery supply could work, but what motors are you using? Are you using a separate power supply for those?
The servos will work with 6V but that's a bit low for the Vin input on a Pro-Mini and too high for the 5V
pin. The pro-Mini should have 7.5 volts. Can you add a single AA battery holder and wire it in SERIES
with the 6V battery pack and use the 7.5V output of the "5th" battery as the Vin for the Pro-Mini ?
(the servos should be powered by the 6V pack only . If is ok if the servo power is tapped off the 6V lead
of the 4-PACK but you should add at least 470uF capacitor on the 7.5V power for the Pro-Mini or the
spike from the servos could cause the uC to reset. As a generally rule , you should NOT be running
servos off a uC PS. That breaks all the rules. The last thing you want on a uC PS is motor spikes.
With a a 4xAA block you might try powering the servos directly from the batteries, and powering the arduino from the batteries thru a small diode to the arduino +5v pin. The diode will drop the voltage from the batteries by ~.7v, and act as an electrical check valve. Put a large high uf value capacitor between the arduino +5v and ground to help keep the arduino voltage up when the servos move.