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6 Volt Electric Motor
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DPDT Switch
6 Volt Battery
Main control Switch
Protected Under
18 U.S.C. 707
DC II Lesson Objectives:
1.
2.
3.
4.
4.
5.
6.
7.
8.
Identify different types of switches and their symbols
Define SPST, SPDT, and DPDT
Review Series Circuit
Review Parallel Circuit
Build a Selector Switch circuit
Adding an Interlock
Build a 3-way switch control circuit
Build a 3-way and 4-way switch control circuit
Look at another application for a DPDT switch
How it works: In this circuit two lamps are wired one right after the other, in series. When
the switch is closed electrons flow from the negative pole of the battery through the switch and
through one lamp and then through the second lamp before returning to the battery.
Challenge:
What happens if you turn one
battery around and connect the
positive to the positive of the
other battery? Try it and find
out!
How it works: Electrical loads are not the only electrical devices that can be connected in
series. Voltage sources like batteries can also be connected in series. By connecting the
battery poles negative to positive the total voltage is 6 volts + 6 volts = 12 volts. The lamps
in series add resistance to the circuit. Since each light bulb is the same type, the total voltage
is divided by 2 across each lamp, in this case 12 volts / 2 = 6 volts at each lamp.
How it works: In this circuit two lamps are wired so one lamp is extended from the other. This
is called a parallel circuit. Look how the red and white wire is in parallel. Trace the electrons
from the negative pole of the battery back to the positive pole. When the switch is closed
electrons have two separate paths through the lamps to get back to the battery. Electrical current
will be more because two lamps in parallel let more electricity flow, faster!
Selector Switch Example 1
Selector Switch – Selecting Between 2 Loads
Selector Switch with an Interlock
Two 3-way Switches Controlling a Load
Adding a 4-way switch- Step 1
Adding a 4-way switch- Step 2
Hope you
had fun!
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Protected Under
18 U.S.C. 707