Electronics_Projects_For_Dummies

320 Part IV: Good Vibrations

Figure 13-16:

Wires soldered to the speed, horn, and start/stop switches.

Repeat after us: Heed all the safety precautions about soldering that we give you in Chapter 2. Use adequate ventilation when soldering to avoid inhaling fumes, and be sure to get a soldering iron with a stable stand so there’s no danger of it falling off your work surface.

6. Secure the breadboard and battery pack in the box with Velcro, as shown in Figure 13-17.

As you place the breadboard in the box, carefully feed the antenna wire out of the box through its hole and secure the antenna wire with a wire clip.

7.Attach the wires from the battery pack, on/off, transmit, speed, horn, and start/stop switches to the terminal blocks, as shown in Figure 13-17.

Chapter 13: Sensitive Sam Walks the Line 321

Wires from start/stop switch

Antenna Wires from horn switch Wires from transmit switch

Figure 13-17:

Transmitter

circuit in

place.

Making the receiver circuit

The receiver circuit will eventually reside in Sam’s body, taking the signals that your remote control unit sends telling Sam how to behave. Here are the steps to build the receiver circuit:

1.Take two 830-contact breadboards and join them by inserting the tabs into the slots along the sides to make one large breadboard.

2.Place the HT12D (IC1), the LM555 (IC2), the L293D (IC3), the receiver module, and ten terminal blocks on the breadboard, as shown in Figure 13-18.

322 Part IV: Good Vibrations

Figure 13-18:

Place the

ICs and terminal blocks on the

breadboard.

3.Place the four RB5-5-S relays (Relay 1–Relay 4) and five 2N3904 (Q1–Q5) transistors on the breadboard, as shown in Figure 13-19.

Insert each transistor lead into a separate breadboard row with the

•Collector lead to the left side, as shown in Figure 13-19

•Base lead in the center

•Emitter lead to the right

The collector pin of Q2 goes in the same breadboard row as Pin 16 of Relay 1. The collector pin of Q3 goes in the same breadboard row as Pin 16 of Relay 2. The pin designations of the 2N3904 transistors and the LM7805 voltage regulator are shown in Figure 13-20.

Chapter 13: Sensitive Sam Walks the Line 323

VR1 Q1 Relay 4 Q5

Figure 13-19:

Place the

RB5-5-S relays, LM7805 voltage regulator, and 2N3904 transistors on the breadboard.

324 Part IV: Good Vibrations

Figure 13-20:

The 2N3904 transistor, LM7805 voltage regulator, and RB5-5-S relays pinout.

4.Insert wires to connect the ICs, voltage regulator, transistors, relays, and terminal blocks to the ground bus. Then insert wires between the

ground buses to connect them, as shown in Figure 13-21.

The ground buses are designated by a negative (–) sign on this breadboard.

Thirty-one shorter wires connect components to ground bus; the two long and one short wires on the left connect the ground buses.

Chapter 13: Sensitive Sam Walks the Line 325

Figure 13-21:

Connect components to ground buses.

5. Insert wires to connect the ICs, the terminal blocks, relays, and the voltage regulator to the +V bus. Then insert wires between the +V buses to connect them, as shown in Figure 13-22.

The +V buses are designated by a + sign on this breadboard.

326 Part IV: Good Vibrations

Figure 13-22:

Connect components to the +V bus.

6.Insert wires to connect the ICs, terminal blocks, relays, and discrete components, as shown in Figures 13-23, 13-24, and 13-25.

The receiver module pinout is shown in Figure 13-26.

Chapter 13: Sensitive Sam Walks the Line 329

Figure 13-25:

Place the rest of the wires.

Pin 14 of IC3 to Pin 11 of Relay 3 Pin 11 of IC3 to right motor TB