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25
Build the circuit shown but initially leave the jumper wires outside the
cup. Turn on the slide switch (S1); nothing happens. Place the jumper
wires into a cup of water and an alarm sounds!
You could use longer wires and lay them on your basement oor, if your
basement oods during a storm, then this circuit will sound an alarm.
Project #47 Simple Water Alarm
OBJECTIVE: To sound an alarm when water is detected.
(STANDING)
Project #48
Simple Salt Water Alarm
Project #49
Ambulance Water Alarm
Project #50
Ambulance Contact Alarm
Add salt to the water and the tone of the alarm is louder and faster, telling
you that salt is in the water you detected. Also, try holding the jumper
wires with your ngers to see if your body can set off the alarm.
Modify the circuit in Project #47 by making a connection between A & B.
The water alarm works the same way but now it sounds like an ambulance.
The same circuit also detects if the jumper wires get touched together, so
connect them to each other. The tone of the sound is now much different.
Therefore, this circuit will tell you if there is water between the jumper
wires or if the wires are touching each other.
Project #51
Build the circuit as shown, and turn on the slide switch (S1). Vary the
amount of light to the photoresistor (RP) by partially covering it with your
hand. You can make screeching sounds by allowing just a little light to
reach the photoresistor.
If you replace the 10mF capacitor (C3) with a 3-snap wire or any of
the other capacitors (C1, C2, C4, or C5), then the sound will be a little
different.
Ticking Screecher
OBJECTIVE: To make fun sounds using light.
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