Electronics_Projects_For_Dummies
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230 Part III: Let There Be Light
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.
Figure 10-14:
The plywood after drilling holes.
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.
Figure 10-16:
Attach resistors to LEDs.
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.
232 Part III: Let There Be Light
Figure 10-17:
Resistors soldered and leads clipped.
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.
Gap
10. Solder the black wires to the leads, as shown in Figure 10-19.
Figure 10-19:
Aclose-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.
Figure 10-20:
Red wires connect long leads of LEDs.
Gap
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.
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.
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.
Red wire from dolphin 1
Black wire from dolphin 1
Red wire from dolphin 3
Black wire from dolphin 3
Red wire from dolphin 5
Black wire from dolphin 5
Figure 10-23:
The breadboard in place.
Black wire from dolphin 2
Red wire from dolphin 2
Red wire from battery pack
Black wire from battery pack
Red wire from dolphin 4 Black wire from dolphin 4
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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.
Figure 10-24:
The finished dancing dolphin product.
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.
You can either lean the display against a wall or hang it as you would a large picture; then enjoy the show at your next dance party.
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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.
Chapter 11
Controlling a Go-Kart,
Infrared Style
In This Chapter
Looking over the go-kart schematic
Laying down the parts list
Breadboarding the transmitter and receiver
Building the go-kart body
Making the go-kart go!
Remote-controlled vehicles are very cool things. You can cause them to zip around your living room, tease your cat, and race with your friends.
Building your own go-kart from scratch and using the power of infrared to control its every move are what this project is all about. How far you go in making a cool-looking car is up to you; here we’ve designed what we call an infrared go-kart — sort of like a VW Bug but just a little bit smaller.
In this chapter, you get to explore creating a go-kart that can go forward and backward and even turn left and right on a dime. Along the way, you pick up all kinds of tips about infrared transmitters and receivers as well as controlling motors.
The Big Picture: Project Overview
After you complete this project, you’ll have a little three-wheeled go-kart that you can control with an infrared transmitter, as shown in Figure 11-1. Here’s the rundown on the key features of this vehicle:
We use three wheels. Why three wheels? No kart you ever saw had three wheels, right? Well, the world of electronic projects isn’t Detroit, so we use three wheels because it’s simpler and it works. As soon as you use four wheels, you have to add a suspension system to ensure that all the wheels stay in contact with the ground, especially when that ground