Project 28
3 Currents
Build the main circuit, and set the meter (M5) to the 1A set-
ting. Push the press switch (S2), turn on the slide switch (S1),
or set the switcher to the top position (turning it on). Turn on
the switches one at a time and in combinations, comparing
the current on the meter.
Project 29
AND Circuit
Place the magnet next to the reed
switch (S9) to turn it on, push the
press switch (S2), and turn on the
slide switch (S1) in different combina-
tions while seeing if the lamp (L4)
lights. Fill out this table with the re-
sults:
Are the three switches connected in series or in parallel?
Give an example of an AND circuit in your home.
If switch S9, switch S1, AND
switch S2 are on then the lamp
will be on. Engineers refer to this
switching combination as an
AND sub-circuit (short for “this
AND that”).
Having to turn on several
switches just to turn on a lamp
seems simple but is very im-
portant. The press switch
could represent an on/off
switch on an electric saw, one
of the slide switches could be
a safety switch on the saw,
and the reed switch could be
a fuse box in your basement.
Safety is very important in
electrical wiring.
S9
S1
S2
L4
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
OFF
ON
ON
ON
OFF
OFF
ON
OFF
ON
ON
ON
OFF
ON
ON
ON
1A
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