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 floor, if
your basement floods during a storm, then this circuit will sound an
alarm.
Project 123
Simple Salt
Water 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 fingers to see if your
body can set off the alarm.
Project 124
Ambulance
Water Alarm
Modify the circuit in Project 122 by adding a 3-
snap wire between points A & B. The water
alarm works the same way but now it sounds
like an ambulance.
Project 125
Ambulance
Contact Alarm
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 122
Simple Water Alarm
A
B
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