Chapter 10
Dancing Dolphins
In This Chapter
Taking a peek at the schematic
Checking off the parts list
Breadboarding the dolphin circuit
Making dolphins out of lights
Lighting up your dolphins
We all know that lighting effects make for a good time at movie premieres and parties. Building a design from lights and making the lights move in sequence can give you a great effect.
In this project, we show you how to create a series of dolphins dancing across the water (well, the plywood). You could just as easily create a series of spaceships in sequential stages of taking off, birds flying through the sky, or just about anything you can imagine.
Along the way, you can pick up some tips about timer chips, decade counters, and the artistic opportunity of stringing lots (and we do mean lots) of LEDs in sequence.
The Big Picture: Project Overview
When you complete this project, you’ll have a wall display sporting five dolphins, outlined in LEDs, that light up one after the other, making them seem to dance across the wall. You can see the little guys jumping and jiving in the finished display shown in Figure 10-1.
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Figure 10-1: The final product: dancing dolphins. |
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Here’s the big picture of the dancing dolphin project:
1. Put together an electronic circuit to control the timing of the light display.
2. Create a template for the dolphins and drill holes in a plywood sheet for five dolphin outlines by using the template.
3. Wire five arrays of LEDs and resistors onto the plywood sheet.
4. Mount the circuit on the plywood, connect the arrays of LEDs to the circuit, and add a plywood board to the back of the project.
5. Turn on the juice (that is, pop in the batteries).
The circuit sends current to each group of LEDs for about two seconds, lighting up and then dimming the dolphins in sequence.
Scoping Out the Schematic
You have but one breadboard to put together for this project, but we make up for that by making you string 5 LED/resistor arrays, each containing 38 LEDs and 19 resistors.
Take a look at the schematic for the board, as shown in Figure 10-2.
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Figure 10-2: The schematic of the dancing dolphin circuit. |
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Getting in the swim: Exploring the dolphin circuit
To make your dolphin shapes light up in sequence, you need to make a circuit that uses a timer chip and a decade counter chip in combination with some resistors and a capacitor plus some transistors. Together, these control how often each of the five dolphins lights up and how long each stays lit.
Here’s the overview of the schematic elements that you use to control your terpsichorean dolphins:
IC1 is a key component of this circuit; it’s an LM555 timer chip that you use to generate a square wave at its output on Pin 3.
IC2 is the other key component of this circuit. This is a 4017 decade counter that takes a square wave and generates ten sequential pulse outputs. A 4017 decade counter does this by placing +V on one of its output pins at a time, one after the other. The 4017 decade counter switches to the next output pin at the start of each cycle of the square wave generated by the timer, as shown in Figure 10-3. This allows you to control the rate at which the 4017 decade counter switches +V to each output pin; this is done by controlling the frequency of the square wave generated by the LM555 timer chip. Because we didn’t want ten dolphins, we connected the sixth output pin (Pin 1) to the reset pin (Pin 15). This applies +V to the reset pin after five dolphins dance across the wall and also resets the counter to the first output pin, skipping the last four output pins altogether.
R1, R2, and C1 are, respectively, two resistors and a capacitor that form the RC circuit that determines the frequency of the square wave generated by the LM555 timer chip.
Q1, Q2, Q3, Q4, and Q5 are 2N3053 transistors that turn on when the output pin of the 4017 decade counter they’re connected to is switched to +V. You use these transistors to supply the necessary current — about 190 milliamps — to light the 38 LEDs in each group.
The 555 timer IC generates a square wave from its output. The frequency of the square wave that is generated is determined by how fast the capacitor fills and drains. You calculate how fast the capacitor fills to two-thirds of its capacity or drains to one-third of its capacity by using the RC time constant equation. You can read more about this equation in Chapter 9.
C2 is a capacitor that reduces the occurrence of noise on Pin 5 of the LM555, which could cause false triggering of the IC. This noise can occur if Pin 5 is left unconnected (also called floating).
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Figure 10-3: You put in one square wave to get out multiple sequential little pulses. |
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Setting up the light show
The circuit won’t mean a thing if you don’t set up the lights for it to control. That’s where the elements of the LED/resistor arrays come in. An array, in this case, equals the lights that define one whole dolphin.
These five arrays each include
38 LEDs, which light up when a river of current runs through them
19 resistors, which are resistors that limit the current running through the LEDs in series with each resistor to approximately 10 milliamps
Take a look at the schematic for these in Figure 10-4. Notice that we have not assigned a number to each LED and resistor. That is because we have 190 LEDs and 95 resistors among the 5 dolphins — and we don’t have time.
These LEDs and resistors are wired together such that two LEDs and one resistor are in series. When +V is applied, current runs through each component sequentially. Each group of two LEDs and one resistor are connected parallel with the other groups of LEDs and resistor. Because 19 LED/resistor groups are in each array, the total current running through an array is approximately 190 milliamps.
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Figure 10-4: The schematic of a LED/ resistor array. |
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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.
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)
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
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Figure 10-5: Key circuit components. |
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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
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
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Figure 10-6: Key components of the LED arrays. |
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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.
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.
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Figure 10-7: Place the LM555 IC, 4017 IC, and six terminal blocks. |
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2. Insert discrete components on the breadboard, as shown in Figure 10-8.
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Figure 10-8: Insert resistors, capacitors, and transistors on the breadboard. |
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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.
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Figure 10-9: The 2N3053 transistor pinout. |
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3. Insert wires to connect the ICs, the battery pack terminal block, and the emitter pin of the transistors to the ground bus. Then insert a wire between the two ground buses to connect them, as shown in Figure 10-10.
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Figure 10-10: Nine shorter wires connect components to ground bus; the long wire on the left connects the two ground buses. |
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4. Insert wires to connect the ICs and the terminal blocks to the +V bus, as shown in Figure 10-11.
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Figure 10-11: Connect components to the +V bus. |
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5. Insert wires to connect the collector pin of the transistors to the terminal blocks, as shown in Figure 10-12.
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Figure 10-12: Connect the collector pin of the transistor to terminal blocks. |
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6. Insert wires to connect the ICs, terminal blocks, and discrete components, as shown in Figure 10-13.
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Figure 10-13: Hook up the IC, terminal blocks, and discrete components. |
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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.
3. Use a marking pen to mark where you want to place the LEDs on the plywood to show the outline of the dolphins.
We used 38 LEDs per dolphin. We spaced the marks about 11/2" apart in the parts of the dolphin where there was little change in shape. Where the dolphin’s shape was a bit more complex (for example, the nose and tail), we spaced them more closely.
4. Drill test holes in a piece of scrap wood to determine the size of drill bit that you should use to give a press fit for the LEDs.
We used a 13/64" drill bit.
5. Drill holes for the LEDs at the locations that you marked in Step 3.
The plywood after drilling is shown in Figures 10-14 and 10-15.
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Figure 10-14: The plywood after drilling holes. |
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Figure 10-15: A closer look at the dolphin templates with all holes drilled. |
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6. Pick a dolphin and start inserting LEDs in the drilled holes.
We suggest starting at either end of the plywood sheet so the LED leads of a finished dolphin aren’t in your way while you work.
7. Attach resistors between every other LED, as shown in Figure 10-16.
Attach the resistors to the short lead on the first LED of each pair and to the long lead on the second LED of each pair. At this point, leave the long lead on the first LED and the short lead on second LED alone.
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Figure 10-16: Attach resistors to LEDs. |
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8. Solder the resistors to the leads and clip the leads just above the solder joint.
Clip only the leads to which you have soldered resistors. Figure 10-17 shows how the dolphin board should look at this point.
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Figure 10-17: Resistors soldered and leads clipped. |
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Be sure to heed all the safety precautions about soldering that we provide in Chapter 2. For example, don’t leave your soldering iron on if you have to step away. And just in case a bit of solder has an air pocket that could cause it to pop, wear your safety glasses whenever you solder.
9. Connect the short leads on every other LED to short lengths of 20 gauge black wire, as shown in Figures 10-18 and 10-19.
Figure 10-18 shows a gap without a black wire across the tail of the dolphin. One of the LEDs at the tail with a short lead has only one black wire attached, and the other has a 2' 20 gauge black wire attached; you connect this wire to a terminal block on the breadboard in Step 20.
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Figure 10-18: Black wires connecting short leads of LEDs. |
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10. Solder the black wires to the leads, as shown in Figure 10-19.
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Figure 10-19: A close-up of black wires connecting short leads of LEDs. |
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11. Connect the long leads on every other LED to short lengths of 20 gauge red wire, as shown in Figures 10-20 and 10-21.
Figure 10-20 shows a gap where no red wire is strung across the tail of the dolphin. One of the LEDs at the tail with a long lead has only one red wire attached; the other has a 2' 20 gauge red wire attached, which you connect to a terminal block on the breadboard in upcoming Step 20.
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Figure 10-20: Red wires connect long leads of LEDs. |
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12. Solder the red wires to the leads, as shown in Figure 10-21.
13. Clip the LED leads just above the solder joint.
14. Make sure that the LED leads and solder joints don’t touch each other and then coat them with liquid electrical tape to help prevent any shorts if wires are bent or pushed together.
15. Repeat Steps 6–11 for each dolphin until you install and wire the LEDs for all five.
16. Chose a location on the plywood sheet to place the battery pack so that you can reach the on/off switch.
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Figure 10-21: A close-up of red wires connecting long leads of LEDs. |
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17. Attach Velcro to the battery pack and the plywood so that you can attach the battery pack to the plywood, as shown in Figure 10-22.
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Figure 10-22: The battery pack in place. |
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18. Chose a location on the plywood sheet where you will place the breadboard.
19. Attach Velcro to the breadboard and the plywood and then attach the breadboard to the plywood, as shown in Figure 10-23.
20. Insert the wires from the battery pack and the dolphins to the terminal blocks on the breadboard, as shown in Figure 10-23.
If the wire on the battery pack isn’t long enough to reach the breadboard, splice and solder longer 20 gauge red and black wires. Protect the splices with electrical tape or heat shrink tubing.
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Figure 10-23: The breadboard in place. |
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21. Secure the wires with wire clips.
22. Add the protective backing by performing the following steps:
a. Drill holes for 6-32 screws in six locations on each plywood sheet to attach the standoffs between the two plywood sheets.
b. Secure the six standoffs to the plywood sheet on which you’ve placed the LEDs, using 6-32 screws.
c. To finish off the project, secure the second plywood sheet to the six standoffs using 6-32 screws, as shown Figure 10-24.
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Figure 10-24: The finished dancing dolphin product. |
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Trying It Out
We’re sure that after spending hours stringing LEDs, you’re eager to see the fruits of your labors. (We were!) Whether you followed our lead and created dolphins or got creative with some other shape, it’s time to turn on your lighting display.
There aren’t many steps to getting this project going:
1. Pop the batteries into the battery pack.
2. Flip the switch to On.
That’s it! Your dolphins will begin dancing across the wall in timed sequence.
Here are the obvious things to check out if you’re having a problem:
All the batteries are fresh and tight in the battery pack and also face the right direction.
If one dolphin in the group doesn’t function, check its wiring.
If one or two LEDs aren’t working, replace them.
If two LEDs in series with each other aren’t functioning, you might have reversed the long and short leads of the LEDs. If so, it’s easiest to just replace that pair.
Taking It Further
Aren’t dancing dolphins just so cool? You can morph these guys into something else or expand their functionality in a few different ways:
Change the stencils to create whatever your heart desires.
Santa and his reindeer, or swans, or leaping lizards come to mind.
You can create larger figures or make up to ten figures.
However, we wouldn’t suggest using more LEDs than we used here to outline them because that would drain the batteries too quickly or possibly cause the 2N3053 transistors to overheat.
Get your dolphins chattering in sequence.
You could add sound by using a sound chip, as we show you in Chapter 14.
Use a SpeakJet sound synthesizer chip (like we show you in Chapter 7) to have each dolphin make a unique sound, giving each a distinctive personality.
Tie an output pin of the decade counter to an event pin on the SpeakJet sound synthesizer chip in parallel with the transistor for the LEDs. Program the SpeakJet to trigger an event when it goes from low to high. When a dolphin lights up, it triggers the sound for that pin.