Elenco Snaptricity&reg - Manual (Page 76)

5V
-75-
Buzzer (II) Project #66
Educational Corner:
Snappy says: This
circuit is similar to an
electric bell. Instead
of having a snap piece
vibrating, there is a
hammer hitting a bell.
Sound is a variation in air pressure created by a mechanical vibration. For a demonstration of this, lay
one of your stereo speakers on the floor, place your hand on it, and turn up the volume. You should feel
the speaker vibrate. Now place a piece of paper on the speaker; if the volume is loud enough, you will
see the paper vibrate.
FOR ADVANCED USERS -
ADULT SUPERVISION RECOMMENDED
This circuit is a feedback loop which raises and releases the nut-snap in a
repeating cycle. The buzzing sound you hear is from raising and releasing the
nut-snap many times a second.
When you hear buzzing, the current is very small but the meter (M5) needle will
be vibrating, because the circuit is turning on and off rapidly. If there is no sound,
then the current should be about 0.1A, due to the resistance of the electromagnet.
Description
Set the slide switch (S5) to position B to turn on the circuit. Adjust the position of
the grommet until you hear a buzzing sound. Make sure the 4-snap lays centered
on the snap at C4 (vibration tends to move it off-center); it should lay there without
being snapped. The meter measures the current.
This circuit requires precise adjustment; if it doesn’t work, then make sure the
grommet and 4-snap are positioned as described above and start over. If you still
can’t get it to work, rotate the 1-snap at location A6 to the proper spring direction
as shown, this may make the 4-snap move more easily.
Operation
Build the circuit shown. Two 3-snaps are stacked together at base grid location B2-
B4, two snaps are stacked together at grid location B4-C4, and three 2-snaps are
stacked together at grid location C5-D5. Snap the 4-snap onto the 1-snap at A6,
then place it so it lays on the snap at C4 (DO NOT SNAP IT ON). Place the nut-
snap on the 4-snap so it will be under the electromagnet (M3). This circuit works
best with new alkaline batteries.
Place the rubber grommet on the iron core rod and push the rod into the
electromagnet until it is just barely above the nut-snap without touching it (0.025
inches).
Assembly
Electric Paths
Note spring
direction of
1-snap