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The Fahnestock clips, which accomodate headphones with
separated terminals, may be installed wherever you like.
Possibly your headphone set (or single headphone) has a
phone-plug connector. In that event youíll have to obtain a
With a pointed tool, jab four holes in the cigar-box, as illustrated, to pass wires through. This operation isnít necessary, as you can see, since the microphone can be completely wired at the front of the box. But it does result in a neater-looking job. Assuming youíve made the holes, run a wire from the upper electrode screw into the box and then back out of the box to the center terminal of the battery. Do the same at the lower electrode, except run the wire to the screw on the outer Fahnestock clip. Conclude the hookup by linking the inner clip to the corner battery terminal. Now letís put our workmanship to the test and see how well the mike operates.
Using the Mike
Connecting your headphones to the microphone completes the circuit and turns the mike on. Youíll be amazed at the new world of sound opened up to you. You should be able to hear your own breath blown against the pencil lead. Grains of salt dropped on the electrodes should sound like rocks; tapping the box with your fingernail might pass for a mild explosion. Try placing a spring-wound alarm clock or wrist watch on the box. Also lean a transistor radio against the box; even with the volume set low, youíll be able to hear the program through the headphones. The radio experiment will be even more impressive if you can put the mike in one room and the headphones in another.
What else can we do with the mike? Well, how about using a sewing needle instead of the pencil lead? Try it with the point down, then with the point up; turn it to find spots of higher sensitivity. Lay the box flat. Hold it against a wall and have someone talk on the other side of the wall. Also, see what hap- pens when you adjust the electrodes, change pencil-lead hard- ness, or substitute a flashlight battery for the 6-volt battery.