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Running down receiver and container parts ..................................

The circuit that takes transmitted signals and explains to Sam what’s expected
of him involves the following parts, several of which are shown in Figure 13-6:

Holtek HT12D decoder (IC1)

L293D H-bridge (IC3)

LM555N-1 timer (IC2)

Five 2N3904 transistors (Q1–Q5)

6 volt buzzer

RWS-434 RF receiver module

We bought this at Reynolds Electronics; Hobby Engineering carries a

similar module.

Four 1 amp or greater solid state relays, DPDT (double-pole, double-

throw) or SPDT(single-pole, double-throw)

We used the Shinmei RSB-5-S DPDT that we found at Jameco (www.

jameco.com). A SPDT would also work, but we used the DPDT because

it allows for more flexibility for which side of the relay we could run

wires to. Make sure that the relay you buy has a pinout pattern that fits a

breadboard; many of them do not.

Two DC gear motors GM2 each with a 2^5 ⁄ 8 " wheel or equivalent

We use these because the suppliers (Hobby Engineering (www.hobby

engineering.com) or Solarbotics Ltd. (www.solarbotics.com)

carry wheels made to fit them.

Two metal brackets used as motor mounts

We found 3" x^5 ⁄ 8 " mending braces made by National Manufacturing

Company at our local hardware store. These worked great.

One 1^1 ⁄ 2 " inch swiveling castor

Six 0.1 microfarad ceramic capacitors (C1, C3, C6, C7, C9, C11)

Six 10 microfarad electrolytic capacitors (C2, C4, C5, C8, C10, C12)

51 kohm resistor (R1)

Three 10 kohm resistors (R3, R5, R7)

Two 150 ohm resistors (R4, R6)

330 ohm resistor (R2)

Two 830-contact breadboards

Two Fairchild QRB1134 sensors

Chapter 13: Sensitive Sam Walks the Line 311