Page 186 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

164 Making Things Move

• On-off toggle switch (like SparkFun COM-09276) or other SPST switch

• TIP120 Darlington transistor (Digi-Key TIP120-ND or Jameco 32993)
• 220KΩ resistor (Jameco 30470)
• Diode (SparkFun COM-08589)

Recipe:

1. Connect the 5V power and ground pins on the Arduino to power and ground
on one side of the breadboard with jumper wires (see Figure 6-29). On the
other side of the breadboard, connect a 9V battery to power and ground.
Make sure that the ground is linked between the ground columns on the
breadboard.

2. Plug the transistor into the breadboard as shown in Figure 6-30, so each of
the three legs has its own row. Connect the emitter pin of the transistor to
ground on the breadboard.

3. Connect pin 9 on the Arduino to the base pin of the transistor.

FIGURE 6-29 Powering a breadboard with the Arduino