Page 133 - 15 Dangerously Mad Projects for the Evil Genius

112 15 Dangerously Mad Projects for the Evil Genius

Figure 9-8 The completed transmitter stripboard

transmitter does not work, try the microphone the that can be stripped and tinned, and made ready for
other way around. soldering. This unit also had wires that lead to a
backup battery (toward the bottom of Figure 9-10),
Step 6. Prepare the Transmitter a setup that was designed to remember the radio’s
frequency setting in between uses of the device.
Figure 9-9 shows the FM transmitter in its This feature was deemed an unnecessary
unmodified state. These things are designed to fit complication and those leads can be cut off.
into your car’s cigarette lighter socket and have a Finally, the audio lead can be shortened, stripped,
trailing lead that plugs into your MP3 player. The and tinned, leaving a raw module like that in
unit has a screen and some buttons that allow you Figure 9-11.
to select the frequency on which it broadcasts. You
would then tune your car radio to that frequency to
be able to hear your MP3 player through the car’s
speaker system.
These devices can be bought very cheaply, and
many types are available on eBay for a few dollars.
Although designed to operate from the car’s
12V power supply, these units normally contain a
voltage regulator that drops the voltage to 5V. This
means they are equally happy operating from a 9V
PP3 battery.
If you take your FM transmitter apart, it should
look something like Figure 9-10.

On the left-hand side, you can see the power
leads connected to the car accessory plug. These
can be cut off, leaving leads of two or three inches Figure 9-9 FM MP3 car transmitter