19
The “on” position of a switch is also called the “closed”
position. Similarly, the “off” position is also called the
“open” position. This is because the symbol for a
simple switch is similar to the symbol for a door in an
architect’s drawing of a room:
The electronics symbol for a simple switch should be
thought of as a door to a circuit, which swings open
when the switch is off. The “door” to the circuit is
closed when the switch is on. This is shown here:
Walls
Door
Left Switch Position Open
(turned off)
Right Switch Position
Closed (turned on),
right LED controlled by
press switch
Left Switch Position
Closed (turned on)
Right Switch Position
Open (turned off)
See project 3 if you need to recharge the battery (
B4
).
Open Switch (turned off)
Closed Switch (turned on)
Build the circuit shown. The switcher (
S6
) and
press switch (
S2
) control the lights.
Build the circuit shown and push the
press switch (
S2
) to turn on light or
sound. Switches can be arranged in
many different ways.
PROJECT 14
• Close the Door
PROJECT 15
• Feeling Switchy
As used in this circuit your
S6 switch has 3 positions,
so it has a different symbol:
The press switch allows electricity
to flow from the battery to the
circuit and the switcher (
S6
) directs
the electricity to the red LED (
D10
)
or the melody IC (
U32
). These
switches are like many switches in
your home, controlling lights and
many other things.
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