I have been doing a lot of researching ever since Christmas when I got the Arduino Uno. Anyways, I want to build a 4 leg spider robot using 2 Arduino's. I had a lot of problems on coming up with how to do it, and I think I got it. What I want to be answered is this question, is my circuit good to go and will not fry anything? Anyways, I needed 12 servos. Only 6 pins on 1 Arduino has PWM. So I thought to use 2 Arduino's to communicate through the HC-06 blue-tooth. Power was another problem. I discovered that double AA batteries have an impressive 7 amps on my multi-meter. However, to much for the Arduino. That is why it is only supplying servos and not going directly to the Arduino. A 9v will do that. Anyways, I can't give you guys the schematic as it is to big of a file. However, I will explain the circuit in words. One Arduino is master and the other is slave. These steps go to both master and slave unless stated.
6 servos on master and 6 on slave. Power is going to 4 double AA batteries in series. This supply is not connected to the board except the ground wire. This is a battery holder with switch already on it. All PWM pin's are in use for servos.
9 volt battery going to the Vin pin. I will incorporate a switch.
Fan with positive and negative only. Positive goes to the 9 volt battery. Ground goes to ground pin on Arduino.
Bluetooth module with VCC going to 3.3v pin. Ground to ground pin. TXD going to the RX pin. RXD going to TX pin.
For master Uno only. Distance sensor with Trig going to A5 pin and echo to A4 pin. Ground going to ground pin. VCC going to 5v pin.
2 led's in circuit with 220 ohm resistor. I will use pin 4 and 2. Ground goes to ground pin.
That is the setup. I am in college where soldering is banned. So I am including a fan, like you saw, to cool down the breadboard. Let me know if you think that will work. I could not find a good schematic online for this robot, so I made one. Please let me know if you have any questions. Anyways, please tell me if there are any flaws and thank you so much for your time and effort.