the Parts List) becomes the base of the solar pendulum.
The whole previous assembly is installed on the base by
using four #4 screws to attach the cover to the
The pendulum object needs to have a small
neodymium magnet attached to the very bottom. If you
use a steel globe like in the photos, the magnet will stick
by itself. If you use a non-metallic object for the
pendulum, the magnet will need to be glued in place.
The last assembly step is to adjust the string so that
the gap between the magnet and the cover is at least
1/8 inch and no more than 1/4 inch. The upper nuts on
the top plastic holder must be loosened in order to
adjust the string.
After each adjustment of the string, make sure the
pendulum object is still hanging centered between the
two threaded rods before checking the gap. For the best
performance, try to get the gap at 1/8 inch if possible.
Tighten the top nuts to lock the string in place once the
pendulum gap is set.
■ FIGURE 5.
Operation of your solar pendulum is straightforward
— simply expose it to sufficient light and the pendulum
object should start swinging on its own. Or, you can
always give it a starting nudge. Once it is swinging, you
should see the LED flash each time the pendulum passes
over the hidden coil. Note that direct or indirect sunlight
works the best. An incandescent bulb works okay if held
close enough, but a fluorescent light will not work at all.
This project is a hit with audiences of all ages and it
will keep you and anybody else who watches it
mesmerized for hours. NV
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August 2012 35