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Figure 4 - This interface will connect your phone line to your breadboard
Figure 4 - This interface will connect your phone line to your breadboard

The multipurpose telephone line interface is built using a pair of .1uF capacitors to remove the DC current from the phone line. Figure 4 shows the interface prepared on a small breadboard for use in other projects. The interface is so simple that you could just solder the capacitors right to the end of the telephone cord and then place some heat shrink tubing over them, leaving the free leads of the capacitors to act as plugs for your breadboard. Without this interface, 40 or even 100 volts would be fed directly into your electronic projects, likely causing a total failure of any transistors or ICs.



Figure 5 - The Spammer Jammer schematic is based on a pair of 555 timers
Figure 5 - The Spammer Jammer schematic is based on a pair of 555 timers

The Spammer Jammer Schematic shown in Figure 5 is based around a pair of 555 timers that work together to create a dual tone siren. The first 555 oscillator circuit (IC1) acts like a low frequency pulse generator, changing the tone of the second 555 oscillator circuit (IC2) back and forth like an ambulance siren. The rate that the tones are changed can be controlled by the variable resistor VR1 so that the sound can be slow like a police siren or very fast like an angry screech. All of the sounds are highly annoying and very loud when fed directly into the phone line!

You can mess around with the actual tones of the siren as well by changing the values for C3, R4 and R5 in the second oscillator circuit. The output from the second oscillator is then fed through the telephone interface capacitors (C4, and C5) to introduce the sound into the found line as an AC audio signal. If you don't want to interface to your phone system and need portable operation, a piezo buzzer can be connected from pin 3 on the second 555 timer (IC2) to ground to produce directly audible sounds.

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