Electronics_Projects_For_Dummies
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Chapter 13: Sensitive Sam Walks the Line 331
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Figure 13-27:
Insert capacitors and resistors onto the breadboard.
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Use the following key for the callouts in Figure 13-27.
1.C1 from +V bus to ground bus
2.C2 from +V bus to ground bus
3.C3 from +V bus to ground bus
4.C4 from +V bus to ground bus
5.C7 from +V bus to ground bus
6.C8 from +V bus to ground bus
7.C9 from +V bus to ground bus
8.C10 from +V bus to ground bus
9.C5 from Pin 2 of IC2 to ground bus
10.C6 from Pin 5 of IC2 to ground bus
332 Part IV: Good Vibrations
11.R1 from Pin 15 of IC1 to Pin 16 of IC1
12.R2 from Pin 6 of IC2 to Pin 7 of IC2
13.R3 from Pin 7 of IC2 to +V
14.R4 from right sensor TB to ground
15.R6 from left sensor TB to ground
16.R5 from right sensor TB to +V
17.R7 from left sensor TB to +V
18.C11 from +V bus to ground bus
19.C12 from +V bus to ground bus
Building Sensitive Sam’s chassis
If you’re a sensitive guy like Sam, how your body looks is very important to you. Here are the steps to build Sam a serviceable little chassis to hold the receiver circuit:
1. Solder 12" stranded wires to the motor lugs, as shown in Figure 13-28.
Figure 13-28:
Wires soldered to the motor lugs.
Chapter 13: Sensitive Sam Walks the Line 333
2. Drill holes for the 6-32 screws used to mount the castor, as shown in Figure 13-29.
Use the base of the castor to guide you when marking the four holes you will drill in the chassis box to mount the castor.
Holes for feeding wires Screws for castor |
Screws for motor mounts |
Figure 13-29:
The inside of the box after holes have been drilled and the motors and castor
are mounted.
3.Mark a location about an inch to each side of the castor and drill holes with a 1/4" bit to feed the wires to the motors and sensors, as shown in Figure 13-29.
4.Using a mending brace to mark the four holes you will drill in the box to mount the motors, drill holes for 8-32 screws, as shown in Figure 13-29.
5.Attach the castor to the box with four 6-32 screws and nuts, as shown in Figure 13-30.
6.Attach the motors to the box with two 8-32 screws and nuts and one mending brace for each motor, as shown in Figures 13-30 and 13-31.
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Figure 13-32:
Keeping the sensors just off the floor allows Sam to spot the tape.
8.Mount the sensors in the small box with one 4-40 screw and nut per sensor.
9.Feed the wires for the sensors and the motors through the holes you drilled to each side of the castor.
10. Glue the small box to the cart, as shown in Figures 13-32 and 13-33.
The face of the sensors should be a quarter-inch above the floor.
336 Part IV: Good Vibrations
Figure 13-33:
A look at how we attached the sensors from below.
11.Drill two holes for 6-32 screws to mount the buzzer, as shown in Figure 13-34.
Figure 13-34:
The buzzer and the on/off switch mounted on Sam.
Chapter 13: Sensitive Sam Walks the Line 337
12.Mount the buzzer by using two 6-32 screws and nuts.
13.Drill a hole in the box where you will insert the on/off switch, as shown in Figure 13-34.
14.Slip the threaded shaft of the on/off switch through the hole you drilled and secure it with the nut provided.
If the wall of the box is too thick to allow the threads on the switch to reach the nut, use a small chisel to remove enough wood from the inside wall of the box so that the nut can engage the threads.
15.Solder the black wires from the three battery snaps to one lug of the on/off switch and solder three 12" black wires to the other lug of the on/off switch.
Figure 13-35 shows the switch after soldering.
Figure 13-35:
Wires soldered to on/off switch.
16.Attach Velcro to the breadboard and the box and secure the breadboard in the box.
17.Attach Velcro to the battery packs and the box and secure the battery packs in the box.
18.Insert the wires from the sensors, motors, battery packs, buzzer, and the on/off switch to the terminal blocks on the breadboard, as shown in Figures 13-36 and 13-37.
338 Part IV: Good Vibrations
As you insert the wires, cut each of them to the length you need for them to reach the corresponding terminal block. Also, strip the insulation from the end of the wire.
Figure 13-36:
Connect the sensors, motors, battery packs, buzzer, and on/off switch to the
breadboard.
Chapter 13: Sensitive Sam Walks the Line 339
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Figure 13-37:
A closer look.
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Use the following key for the callouts in Figure 13-37.
1.Red wire from buzzer
2.Black wire from buzzer
3.Red wire from receiver battery pack
4.Black wire from receiver battery pack
5.Red wire from main battery pack
6.Black wire from main battery pack
7.Red wire from motor battery pack
8.Black wire from motor battery pack
9.Wires from left motor
10.White wire from left sensor