1. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Test Bed Assembly

2. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. How do we teach the concepts?

3. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. What purpose does this TEST BED serve? Teaches or refreshes electrical concepts Applies theoretical concepts Prepares the student for the future Competition – Motivates Students

4. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Concepts Covered? Build a teaching tool capable of showing multiple theoretical principles. Experience working with electrical and electronic controls Help the instructor and students build a safe, uncluttered teaching tool.

5. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Board Construction

6. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Vex Controller

7. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Vex Limit Switch

8. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Vex Bump Switch

9. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Vex RF Receiver Module Antenna and Holder

10. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Vex Crystal and Cable

11. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Main Switch

12. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Controls flow of current from battery Mounted before the fuse panel Provides an “Emergency Stop” control in the system Schematic Symbol for “Single Pole, Single Throw” switch Main Switch

13. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Terminal Block

14. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Terminal Block Allows multiple connection access. Allows use of smaller wire to feed multiple accessories.

15. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Fuse Panel

16. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Fuse Panel NEGATIVE (-) = BLACKPOSITIVE (+) = RED

17. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Circuit Protection

18. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. The most common types of circuit protection are fuses and circuit breakers. Circuit Protection

19. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Parts of a blade type fuse Why doesn’t it work? Fuses

20. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Relay 1

21. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Solid-State / Electro-Mechanical Relay Spike is a 20 Amp, H- Bridge Relay Module that is small enough to be remotely mounted almost anywhere on your robot. Spike is designed for driving small motors in forward, reverse, or stop (brake). Spike is opto- isolated at the signal input to protect the Robot Controller against motor noise and return currents.

22. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Solid-State / Electro-Mechanical Relay How it Works

23. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Relay 2

24. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Pulse Width Modulation Controls PWM 1

25. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM What is pulse width modulation? What type of wave is produced? What makes the PWM different from a Solid State electro- mechanical relay?

26. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM PWM’s work on the principle of square waves Longer duty cycles increase the amount of time the motor runs Result : more speed or braking power

27. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM

28. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Pulse Width Modulation Controls PWM 2

29. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Electron Flow For our purposes, we will use the conventional theory stating that current flows from negative (-) to positive (+).

30. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Wires, called conductors, carry the current throughout the circuit Proper wire size (gauge) is important and may be determined at least 2 ways –Mathematical Formula –Charts Size and capacity is rated by professional organizations like AWG (American Wire Gauge). Electrical Wiring

31. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. How Do I Know What Wire to Use? Wires come in different sizes. The maximum current each size can conduct safely is shown. Make sure the wire is capable of carrying the current load. Check what the supply Voltage be. NOTE: When it is critical that voltage reduction is minimal, use a larger diameter wire.

32. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Main Switch

33. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Terminal Block

34. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Relay 1

35. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Relay 2

36. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM 1

37. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM 2

38. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. PWM Control Cables

39. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Relay Control Cable

40. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Test Motors

41. Vex 1.0 © 2006 Carnegie Mellon Robotics Academy Inc. Batteries Always make sure the battery is disconnected before working on any part of the circuit or components. Always make sure the battery is disconnected and removed from the testbed when it is not in use. Always store the battery in a secure, dry place. SAFETY