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When you are ready to see your idea start to take its own physical form, you will need to prototype the circuit. This tutorial explains basic prototyping and voltage regulators.

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Figure 7.6

In this example, connection 1 is the negative lead going to the top long circuit. Connection 2 is one end of a resistor connecting to the negative long top circuit. Connection 3 is the other end of the resistor connecting to a separate vertical circuit. Connection 4 is the anode lead of the LED connecting to the same vertical circuit as connector 3. Not shown is connection 5 and 6. Connection 5 will be the cathode lead of the LED connecting to the positive circuit on the bottom and connection 6 is the positive lead of the 9 volt battery making the bottom long horizontal circuit positive. If you want to try this circuit, use a 9 volt battery, a 1k to 5k resistor, and an LED.

For those of you using a perf board, the connections will be the same but the wires will be twisted together.

Figure7.5

As you can see, I determined the top circuit will be negative and the bottom circuit will be positive. Each of the lines in the middle connect a series of holes which allows you to connect components as illustrated in figure 7.6.

Figure 7.4

Now to explain the schematic. It's fairly simple when you follow the basic intent behind the board. The two long lines on the top and bottom are intended to provide connecting points for the positive and negative power supply to the circuit as shown in figure 7.5.

Figure 7.2

The prototyping board is a little more complex to use, but it makes it easier to alter your circuits. To insert a component in a prototyping board, you just push the pin in one of the available holes (Figure 7.3).

Now that we have our program operating the way we want, we need to make a prototype board to test our product outside of the evaluation kit. This is necessary to insure our project will function in a stand alone environment.

I will be using a prototyping board (figure 7.1) that can be purchased from most any electronics supply outlet. You can also use a perfboard (figure 7.2) , a blank circuit board with holes predrilled in even spaces.

Figure 7.15

On the front side of the chip, insert the second .01uf ceramic capacitor between the center pin (ground) circuit and the third pin (output voltage, 5v) circuit as shown in figure 7.16

Figure 7.14

Insert a jumper wire from the horizontal ground strip to the center (ground) circuit of the voltage regulator.

Figure 7.13

Insert the first .01uf ceramic capacitor in the center pin (ground) circuit and the first pin (input voltage, 9v) circuit as shown in figure7.14.

Figure 7.11

Start by inserting the regulator in the middle of the first three bottom vertical rows with the chip facing the positive strip.

Figure 7.12

Next, insert the battery wires with the positive in the input pin circuit strip for the voltage regulator and the negative wire in the top negative horizontal circuit as shown in figure 7.13.

Next we will construct a 5 volt power supply for the microcontroller. Microcontrollers and other logic devices are sensitive to voltage spikes, so we will use a voltage regulator and several capacitors to insure a smooth, consistent voltage is applied to the microcontroller. The voltage regulator is a standard 7805, a 5 volt voltage regulator and the capacitors are two .01uf ceramic capacitors.

A reference diagram is depicted in figure 7.11 so you can get a top down view of the connections. When you are positioning the 7805 voltage regulator, notice the gray bar on the back of the IC's outline. The gray bar represents the metal heat sink on the back of the IC. With most common voltage regulators, the positive voltage input is on the left, the ground is in the middle and connected to the heat sink, and the output voltage is on the right. The directions are referenced to you looking at the front of the regulator.

Whenever possible, you should test each portion of your circuit to insure it functions properly before moving on to the next task. In this case,we can test this part of the circuit by verifying the input voltage, the output voltage, and the ground.

Start by connecting your multimeter probes to the ground. You can use another jumper wire from the ground circuit or you can use the heat sink of the voltage regulator. The positive probe should be attached to the output wire of the voltage regulator from the pin 3 circuit.

Then connect your 9 volt battery to the circuit. Insure the battery has sufficient power to supply your project. An old battery can cause a lot of frustration in wasted circuit troubleshooting.

Figure 7.18

Your multimeter should read almost exactly 5 volts. If it is registering a negative 5 volts, make sure your multimeter is attached to the circuit properly and the probes are connected to the multimeter properly. If it is registering a value other than 5 volts, insure you have 9 volts entering at the input circuit.