HowTo-Color (8) / Hacking Electronics / Simon Monk / 236-3 / Chapter 9
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Hacking Electronics probably want to make yours longer. This is not a problem, unless you plan to make it longer than a few yards or meters. The 3.5mm plug is of the plastic molded variety, reclaimed from some unwanted lead. The first step is to strip both leads (Figure 9-5a). Note that the stereo plug has two screened connections in one twin cable. The screened ground connections of both channels of the stereo plug can be twisted together. Tin the ends of all the leads, and then solder the resistors together, as shown in Figure 9-5b. Next, solder the stereo and mono leads to the resistors, as shown in Figure 9-5c, and cut and tin a short length of wire to bridge the ground connections. Solder it into place (Figure 9-5d) and then wrap everything in insulating tape, taking care to put tape in between any places where wires could short together (Figure 9-5e).
Figure 9-6 A microphone module
How to Use a Microphone Module Microphones (mics) respond to sound waves, but sound waves are just small changes in air pressure, so it is not surprising that the signal you get from a mic is usually very faint. It requires amplification to bring it up to a useable level. While it is perfectly possible to make a little amplifier to boost the signal from your mic, you can also buy a mic module that has an amplifier built in. Figure 9-6 shows such a module. The mic module just requires a supply voltage between 2.7V and 5.5V. This makes it ideal for interfacing with an Arduino. In Chapter 11, you will find out a bit more about oscilloscopes. But for now, here is a sneak preview of what an oscilloscope will display (see Figure 9-7) when connected to the mic module while a constant tone is being generated and the module is supplied with 5V.
Figure 9-7 The output of the microphone module
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