Electrical Connections

Gather the Parts

For this construction step, you will need:

  • Assembled robot
  • (5) 1.5 V AA batteries - don't put them in yet!
  • Needle-nose pliers - optional but helpful
  • Masking tape
  • Pen

Battery Type Matters!
The Feedback 360° servos do best 6 to 8 volts.  Five alkaline batteries provide 5 x 1.5 V = 7.5 V.  Five NiMH batteries provide 5 x 1.2 V = 6 V.  NiMH batteries perform well, but Ni-Cad rechargeable batteries do not perform well in this application and are not recommended.

Label the Cables

  • Put a masking tape label on the end of each encoder cable and servo cable, near the 3-pin socket.
  • Trace each cable back to its origin to see what it is connected to.
  • Label each cable Right or Left, Encoder or Servo. 

Prepare the Servo Ports

Each pair of 3-pin servo ports along the top of the Propeller Activity Board (original or WX version) has a jumper on power-select pins to its immediate left. 

Important! Make sure there are no cables plugged into the board.  Moving jumpers with power connected could damage your board.

  • Unplug the USB cable and battery pack if you have either of them plugged into the board.
  • Move the shunt jumpers into the configuration shown below. (If your jumpers don't have a little tab on them, needle-nose pliers will help.)
  • P12 & P13: VIN
    P14 & P15: 5V
    P16 & P17, 5V

Missing a Voltage Selection Jumper? Replacements are available  - contact our sales department to order part #452-00043; there are three per board.

Plug In the Cables

The servos and the external encoders have 3-wire cables: white = signal, red = power, black = ground.  When plugging these cables into servo headers, be sure to align white wires with the I/O pin labels along the top of the board, and the black wires along the row labeled GND.

The Feedback 360° servo also has a single yellow encoder feedback signal wire, which plugs onto a separate servo header's I/O pin - closest to the top edge of the board.

  • Plug the servo's white-red-black cables into these servo ports
    P12: Left Servo
    P13: Right Servo
  • Plug the encoders into these servo ports, making sure the white or yellow signal line connects to the port's I/O pin - closest to the top of the breadboard.
    P14: Left Encoder
    P15: Right Encoder

With external encoders (left/top);  with Feedback 360° servos (right/bottom)


*P14/P15 resistors (shown on left) are only needed for ActivityBot kits using External Encoders (#32500).

Double-check your Connections

  • P12 & P13 servo port shunt jumper — Set to VIN
  • P14 & P15: servo port shunt jumper — Set to 5V
  • Left servo cable — P12 servo port
  • Right servo cable — P13 servo port
  • Left feedback wire — P14 servo port I/O pin, closest to the edge of the board
  • Right feedback wire — P15 servo port I/O pin, closest to the edge of the board



Insert the Batteries

  • Place five 1.5 V AA batteries into the battery pack. 
  • Plug the battery pack's barrel plug into the Propeller Activity Board's (original or WX version) barrel jack.