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little solar cell is providing electrical energy which is charging the high-capacity capacitor. When the voltage reaches a certain threshold level, the 1381 triggers the output circuit, which dumps the power in the capacitor through the motor, creating movement.

The first step of assembling your Solaroller is illustrated in Figure 15-6. You are going to need to take the axle and thread it through the two holes in the circuit board named "rod."

Figure 15-5 The Solaroller schematic. Image courtesy Solarbotics.

Figure 15-6 Step 1—assembling the Solaroller. Image courtesy Solarbotics.

Next, take the high-capacity capacitor, bend the leads so that they are flush with the body of the capacitor. Then solder it into the PCB. Ensure that you solder this in the correct orientation.

Next, take the 2.2 k resistor and solder it as shown. The orientation of the resistor is unimportant.

The next stage in assembly is shown in Figure 15-7.

First take the 3904 transistor and solder it at the head of the board in the orientation shown in Figure 15-7.

Now the 1381 and 2906 transistors are soldered in either side of the board facing down. This is also illustrated in Figure 15-7.

Finally take the small fuse clip which will be acting as our motor mount and solder it into the bottom of the board. Note that the fuse clip has a small lip to prevent the motor sliding out. Ensure that you orient this correctly.

Now you have got this far you are definitely cooking with gas! . . . or should that be with solar? Now take the small high-efficiency motor and insert it into the fuse clip in the manner shown in Figure 15-8.

Figure 15-7 Step 2—assembling the Solaroller. Image courtesy Solarbotics.

Figure 15-6 Step 1—assembling the Solaroller. Image courtesy Solarbotics.

Figure 15-7 Step 2—assembling the Solaroller. Image courtesy Solarbotics.

Adding the wheels at the front is a simple procedure of pushing them onto the axle and then adding the small black plastic clips which will retain the wheels and prevent them from sliding off. Now take the motor leads which are very delicate so treat them with a lot of respect! The red one should be soldered into the hole on the PCB, the blue one should be soldered onto one of the holes near the fuse clip (Figure 15-9).

Next take a small piece of thick copper wire and separate the insulation from the copper wire (making sure that you keep the insulation intact as we will be needing this later!). The wire should be bent at one end and soldered first into the hole adjacent to the motor clip, and then to the motor clip itself to provide mechanical support (Figure 15-10).

Figure 15-9 Step 4—assembling the Solaroller. Image courtesy Solarbotics.
Figure 15-10 Step 5—assembling the Solaroller. Image courtesy Solarbotics.
Figure 15-11 Step 6—assembling the Solaroller. Image courtesy Solarbotics.
Figure 15-13 Step 8—assembling the Solaroller. Image courtesy Solarbotics.
Figure 15-14 Step 9—assembling the Solaroller. Image courtesy Solarbotics.

Next, take a short length of that insulation that you saved and slide it onto the motor shaft. Now take the wheel and slide it over the insulation (Figure 15-11).

The next step is dead simple! Trim the axles at the front of your Solaroller (Figure 15-12).

Now tin the pads on the back of the solarcell (Figure 15-13).

Now solder the wires to the tinned pad, and add a little dab of glue in an area away from the soldered joints to act as a strain relief (Figure 15-14).

Now solder the connections to the printed circuit board (Figure 15-15).

Hold the cell to the light, supporting your solar vehicle and check that it works. Now that you have proved that the circuitry works, fix the solar cell to your vehicle chassis.

Project 40: Hold Your Own Solar Car Race

You will need

• Lap timer 200 software and a PC

OK, so the World Solar Challenge, and the North American Solar Challenge might be a little out of your reach; however, holding your own tabletop solar car race certainly isn't.

The free lap timer software presents a high-tech alternative to simply using a stop watch to time your cars. The software comes with schematics to

Lap timer software is a free download from: www.gregorybraun.com/LapTimer.html

build a PC interface for sensors which will sense when your car crosses the line.

You might like to consider how you can make your team vehicles look different. A little customization with paint and graphics goes a long way!

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Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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