■ Vibration Monitor Schematic.
battery compartment’s spring.
I had trouble making a contact for the other end of
the board. At first, I tried to make a contact similar to the
positive end of a battery but the contact was poor and
intermittent. I ended up taking a 3/4” length of solder
braid and soldering it to the bottom square pad on the
board with its tail coming out to the right side. When
putting the board into the box, I threaded it through the
contact slot and into the first turn of the spring for the
battery (on the left). This solved the problem.
If you want to have adjustable sensitivity, solder the
R2 alternate potentiometer to the board and leave the
fixed R2 vacant. Mount the two ICs, diodes, and R1 and
R2 (if you want fixed amplification) to the top of the
board. The square pads are pin 1. Watch the polarity of
C1 and bend the leads so C1 will lie flat on the board and
then solder. Screw a 3/8” 2-56 screw from the top side
into the tapped hole.
Turn the board over. Bend the piezo transducer leads
at right angles where the contacts enlarge (no polarity)
and solder on the bottom side of the board. Make sure
that the sensor is centered with the board and that the
piezo film is about 1/16” above the bottom (of the board)
so that it can vibrate. Solder the speaker, noting its
polarity on the bottom side. The screw should be
protruding next to the speaker.
Place the board into the center position of the battery
compartment and add two AA batteries to each side (note
their polarities). Turn on the switch and set the unit on a
quiet counter. After a minute, strike the counter with your
hand. This should sound the alarm. Reset the unit by
turning off the switch.
Once the unit is tested, glue the speaker to the
bottom of the box so the board will not move. Replace
the battery cover and secure it with the small screw to the
Uses PARTS LIST
Battery Holder 1 ea
C1 1 ea
D1-D2 2 ea
IC 1 1 ea
IC 2 1 ea
Piezo Vibration Detector 1 ea
R1 1 ea
R2 1 ea
R2 Alternate 1 ea
Screw 1 ea
Speaker 1 ea
Shipping and handling
10 µF 16 volt radial
100K 1/8 watt
1,000 1/8 watt
2230 Damon Rd.
Carson City, NV 89701
This device can be used as an
intrusion alarm or as an earthquake
detector by changing its amplification.
How about as a computer alarm if
you walk away from your desk? It also
could be used for analyzing motor
vibration frequencies, or perhaps as
an anti-feedback controller for
microphones since there is plenty of
room for more code. For remote
monitoring, a relay can be substituted
in place of C1 and the speaker. Run
wires to a light or bell.
Here’s to finding your own good
June 2010 35