Data Sheet

Figure D shows the output waveforms most
important to the operation of the Sound Activated
Switch. When a waveform is created by a clap, it
causes the first one-shot to trigger, causing its
output to switch to a logic 0. When the first one-
shot’s output switches back to a logic 1, the second
one-shot triggers, causing its output to change to a
logic 0. When another waveform is created due to
another clap, the one-shot will trigger again causing
its output to go low once more. When the first one-
shot switches to a logic 0 the
second time, the flip-flop is
activated, causing its output logic
level to change.
Rotate P1 fully counter-clockwise and connect a 9
volt battery. Stand about 10 to 20 feet away from the
Sound Activated Switch. Clap twice with a short
pause between the two claps. The LED should turn
on, or it should turn off if it was already on. If the
LED did not change, rotate P1 clockwise a small
amount and repeat the same steps as above.
Repeat this procedure until the Sound Activated
Switch is operating properly.
OPERATING PROCEDURE
Figure D
-6-
1. One of the most frequently occurring problems is
poor solder connections.
a) Tug slightly on all parts to make sure that
they are indeed soldered.
b) All solder connections should be shiny.
Resolder any that are not.
c) Solder should flow into a smooth puddle
rather than a round ball. Resolder any
connection that has formed into a ball.
d) Have any solder bridges formed? A solder
bridge may occur if you accidentally touch
an adjacent foil by using too much solder or
by dragging the soldering iron across
adjacent foils. Break the bridge with your
soldering iron.
2. Be sure that all components have been mounted
in their correct places.
a) The LED will not light if it has not been
installed correctly. The flat side of the LED
should be in the same direction as shown in
the top legend.
b) Are capacitors C7 and C10 installed
correctly? These capacitors have polarity,
be sure that the positive lead is in the correct
hole.
c) Be sure that the ICs are installed correctly.
d) Be sure that transistors Q1 and Q2 have
been installed correctly. The flat side should
be in the same direction as shown on the top
legend.
e) Microphones have polarity. The negative
lead is always from the pad and shorted to
the case. The PC board is marked to show
the lead positioning.
Consult your instructor or contact Elenco
®
if you have any problems. DO NOT contact your place of purchase
as they will not be able to help you.
TROUBLESHOOTING