Project 30—Strong Pulse Shocker
Figure 7-9 Transformer, battery, and motion switch
shocker sit around waiting for a curious victim to pick it up and get an unexpected wallop. You will need the same type of transformer as used in the last project, a 9-volt battery and some type of motion-activated switch, such as a mercury or ball switch. The components are shown in Figure 7-9. A motion switch will close the circuit when it is tilted or shaken, so it is a perfect solution to give this project automatic operation. These switches can be ordered from electronics supply stores or found in older dial-type thermostats and electric heaters with automatic tilt sensors. You can even make your own crude motion switch by hanging a bolt on a spring so that it hits a metal ring if tilted. I find that the mercury switch is the best solution, since they are completely silent, never wear out and can be easily mounted to the enclosure using a tie wrap or bit of tape. Ball switches also work very well but are not quite as sensitive to motion. Both types of motion switch are shown in Figure 7-10: the mercury switch on the bottom and the ball switch on the top. Keep in mind that mercury is a toxic substance, so avoid breaking the glass casing that contains the mercury ball. As shown in Figure 7-11, the pulse shocker schematic is not much different than the last project using the same transformer, but we have added the secondary winding into the works. By applying power to the secondary, we induce a much higher voltage across the primary windings, essentially
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Figure 7-10 Mercury switch (bottom) and ball switch (top)
+
Output 9V
B Motion switch
Secondary
Primary
Figure 7-11 Pulse shocker schematic
reversing the job that this transformer was once doing in the appliance it was taken from. Depending on the ration of windings, you could expect anywhere from 100 to 500 volts on the output, and I promise you that the strength of the jolt will certainly be more intense than the last version of this project. Again, the current is very low, but you will indeed feel the sting of many angry electrons through your joints. As shown in Figure 7-11, the motion switch momentarily completes the circuit so that the primary winding is induced with a large voltage, which is delivered directly to the hands of the unsuspecting user. Also note that often the secondary winding will have several wires, with three being the most common. We are looking for the pair of wires with the least amount of turns, so you can either measure each pair with an ohm meter