Circuits

1
Circuits
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Schematic Symbols
Battery 3V, 4.5V, 6V, etc.
Cell 1.5 volts
3
Output of a Battery
2.0
1.5
Voltage
1.0
0.5
0
Time
4
Output of a Battery
2.0
1.5
1.0
Voltage
0.5
0
Time
5
wires...
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Standard Wire Sizes
Small diameter Small cross-section Higher gauge
number AWG 20 Higher Resistance per foot
Larger diameter Larger cross-section Lower gauge
number AWG 16 Lower Resistance per foot
AWG 12 is a larger wire than AWG 24
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Standard Copper Wires

• AWG 6 has 0.4028 ? per 1000 ft.
• AWG 12 has 1.619 ? per 1000 ft.
• AWG 24 has 26.17 ? per 1000 ft.
• AWG 32 has 63.21 ? per 1000 ft.

American Wire Gauge
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Stranded Conductors

• Used in situations where wires will be flexed,
  such as an appliance cord.
• Also on power transmission lines (where inner
  wires are typically steel and outer wires are
  aluminum)

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Common Switches
10
Single Pole Single Throw Switch - 2 terminals only
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Variety of Switches
DPDT
DPST
SPDT
DPDT
12
Simple Series Circuit
Lamp
6 VDC
S1
13
Simple Series Circuit
14
Simple Series Circuit
15
In a Series Circuit there is only one path for
current
16
In a Series Circuit there is only one path for
electrical charges to flow.
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A break anywhere in the path stops current flow.
Lamp
S1
6 VDC
18
Rule

• A series circuit has only one path for current to
  flow, so a break anywhere in that path stops the
  flow of current in the entire circuit.

19
Series Circuit
6 VDC
20
Series Circuit
6 VDC
21
Series Circuit
6 VDC
22
Series Circuit
6 VDC
23
Series Switching Circuit
Open
S1
9 V
V 9
t
L1
24
Series Switching Circuit
Open
S1
9 V
V 9
t
L1
Wires extend potential points of battery
terminals
25
Series Switching Circuit
Closed
S1
0 V
V 9
t
9V
L1
26
Rule

• Resistance causes voltage drop

27
Circuit using SPDT Switch
M
28
Circuit using SPDT Switch
M
29
Circuit using SPDT Switch
30
Circuit using SPDT Switch
Lamp
S1
M
SPDT
Motor
31
Controlling two separate circuits with a DPST
switch
Motor
M
24 VDC
L1
DPST
6 VDC
32
Controlling two separate circuits with a DPST
switch
Motor
M
24 VDC
L1
DPST
6 VDC
33
Circuit using SPDT switch as SPST switch
Lamp
S1
6 VDC
34
Circuit using SPDT switch as SPST switch
Lamp
6 VDC
35
Two lamps controlled by two SPST switches -
parallel circuit
S1
S2
6 VDC
L1
L2
36
Two lamps controlled by two SPST switches -
parallel circuit
S1
S2
6 VDC
L1
L2
37
Two lamps controlled by two SPST switches -
parallel circuit
S1
S2
6 VDC
L1
L2
38
Two lamps controlled by two SPST switches -
parallel circuit
S1
S2
6 VDC
L1
L2
39
In a parallel circuit, each branch has source
voltage across it.
S1
S2
6 VDC
6V
L1
L2
40
In a parallel circuit, each branch has source
voltage across it.
S1
S2
6 VDC
6V
L1
L2
41
In a parallel circuit, each branch has source
voltage across it.
S1
S2
6 VDC
6V
6V
L1
L2
42
In a parallel circuit, there is a separate
current flowing in each branch
S1
S2
current 1
current 2
6 VDC
6V
6V
L1
L2
43
Rule

• Parallel circuits have more than one path for
  current.