Electronics_Projects_For_Dummies

Chapter 10: Dancing Dolphins 221

Building Alert: Construction Issues

The back of the dolphins — where all the resistors and LED leads are soldered together — gets kind of hectic. Make sure that if a lead gets bent in the course of putting it on the plywood that it doesn’t short. Rather than using electrical tape, we used liquid electrical tape to coat the exposed leads.

For a mounting surface, we used 1⁄4" sheet plywood as the best bet. We tried using PVC (a kind of plastic) sheets, but they weren’t rigid enough to support the display.

We won’t kid you: Stringing the LED and resistor arrays takes some time and patience. There is no real shortcut to offer you here! We recommend that you solder the resistors to the LED leads first and then attach and solder either the red or black wires. If you try to attach all the wires before you solder, some will get in the way of your soldering iron.

You can use any artwork you like to create the images of your choice. We found a simple clip art drawing of a dolphin, printed it, copied and enlarged it, and used that as our stencil. We tipped the stencil at different angles across the plywood, creating a feeling of movement. However, you can use any graphic for your template as long as you avoid using anything so complex that people can’t make it out by looking at a simple outline of lights.

Perusing the Parts List

It’s time to go shopping for those electronic parts you use to build the circuits and assemble all those LEDs into dancing dolphins. This is where we give you the parts lists for the circuit and the LED arrays.

A circuit with a porpoise

The circuit that controls the timing of your light show involves the following parts, several of which are shown in Figure 10-5:

47 kohm resistor (R1)

470 kohm resistor (R2)

LM555 timer (IC1)

4017 decade counter (IC2)

1 microfarad electrolytic capacitor (C1)

222 Part III: Let There Be Light

0.1 microfarad ceramic capacitor (C2)

Five 2N3053 transistors (Q1, Q2, Q3, Q4, Q5)

Breadboard (830 contacts)

Six 2-pin terminal blocks

An assortment of different lengths of prestripped short 22 AWG wire

Electrolytic capacitor

Figure 10-5:

Key circuit components.

Transistor

Making your dolphins boogie

Here’s your shopping list for building your dancing dolphin light display. This part of the project involves the following parts, several of which are shown in Figure 10-6:

190 orange T-1 3⁄4 LEDs

95 220 ohm resistors

Six 5⁄8" 6-32 flathead screws

Chapter 10: Dancing Dolphins 223

Six 2" standoffs with 6-32 threads

Several feet of black 20 AWG wire

Several feet of red 20 AWG wire

A four pack of AA batteries with an on/off switch

An assortment of different lengths of prestripped short 22 AWG wire

Seven wire clips

Two sheets of 1⁄4" plywood measuring 2' high x 4' wide

Liquid electrical tape

Figure 10-6:

Key components of the LED arrays.

LED

Resistor

Taking Things Step by Step

To make a dolphin dance a two-step, you have to do a few things. First, you have to build the circuit that makes it all run. Then you have to assemble the lights that outline the dolphins on a surface, such as plywood. That’s what we cover in this section.

224 Part III: Let There Be Light

Making the circuit

Time to go one-on-one with your breadboard. Here are the steps involved:

1.Place the LM555 IC, the LM4017 IC, and six terminal blocks on the breadboard, as shown in Figure 10-7.

The six terminal blocks in this figure will be used to connect two wires each to various components in the circuit. The wires from one terminal block go to the battery pack, and the wires from each of the other terminal blocks go to one of the LED/resistor arrays.

Figure 10-7:

Place the

LM555 IC,

4017 IC, and

six terminal

blocks.

2. Insert discrete components on the breadboard, as shown in Figure 10-8.

Chapter 10: Dancing Dolphins 225

C2 from Pin 5 of IC1 to ground

R1 from an open region to +V

Figure 10-8:

Insert resistors, capacitors, and transistors on the breadboard.

R2 from Pin 6 of IC1 to R1

C1 from Pin 2 of IC1 to ground

Figure 10-9 identifies the pins of the 2N3053 transistors.

You insert each transistor pin into a separate breadboard row, placing the collector pin nearest to the terminal block, and then insert C1 with the shorter of the two pins of C1 in the ground bus and the longer pin in the same breadboard row as Pin 5 of IC1.

228 Part III: Let There Be Light

5.Insert wires to connect the collector pin of the transistors to the terminal blocks, as shown in Figure 10-12.

Figure 10-12:

Connect the collector pin of the transistor to terminal blocks.

6.Insert wires to connect the ICs, terminal blocks, and discrete components, as shown in Figure 10-13.

Chapter 10: Dancing Dolphins 229

Pin 2 of IC1 to Pin 6 of IC1

Pin 7 of IC1 to R1

Pin 10 of IC2 to base pin of Q5

Pin 1 of IC2 to Pin 15 of IC2

Pin 4 of IC2 to base pin of Q3

Figure 10-13:

Hook up the IC, terminal blocks, and discrete components.

Making dolphins

All the brains of the circuit assembled in the previous section are there to make the dolphin light display work.

Follow these steps to create your dancing dolphin display:

1. Make five dolphin (or another figure) stencils, each about 11" high.

You can create a template by printing a piece of clip art or other simple drawing and enlarging it with a copier.

2.Decide where you want to place the dolphins on the plywood and use double-sided tape to affix the templates.