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Introduction to Electronics
Basic Electronics
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What is electricity?
How is it measured?
Terms
Ohm’s Law
Kirchhoff's Laws
Power
Putting it together
Power Distribution
What is electricity
• Electricity is the flow of electrons in a
conductor
• Electricity is measured in:
– Voltage (V) – similar to pressure, this is the force
available to drive the electricity measured in Volts
– Current (I) – this is the flow of the electricity
measured in Amps
– Power (W) – this is the power used or available
measured in Watts
Other electrical terms
• Resistance
– a measure of a material’s resistance to the flow of electricity
– measured in ohms Ω
• AC Current
– current that flows first in one direction then in the opposite direction
• DC Current
– current that flows in one direction
• Open Circuit
– a broken current path
• Close Circuit
– a complete current path
• Short Circuit
– when current does not flow where intended
Ohm’s Law
V=IR
Voltage equals Current times Resistance
• What can cause Resistance?
– Wires; the smaller the wire or the longer the run
the greater the resistance
– Circuitry
– Bad Connections
– Anything between the power source and the load
Identify
Kirchhoff's Laws
• Voltage
– There must always be a closed path for current to
flow
– Summation of voltages around any closed loop is
0
• Current
– Summation of currents into a node must equal 0
Power
W=VI
Power equals Voltage times Current
• 746 Watts = 1 Horsepower
Putting it together
Simple Circuit
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V1
Current
(I)
Battery (V)
Resistor (R)
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If V is 10 Volts and R is 10 ohms, what is I?
What is the power used by the Resistor?
V2
Putting it together cont.
Motor Circuit
V3
R
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V1
I
V
Motor
(RM)
V2
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If V is 10 Volts and RM is 10 ohms, what is I?
What is the power used by the Motor?
If V is 10 Volts and R and RM are 10 ohms what is I?
What is the power used by the Motor?
Putting it together cont.
The resistance of a motor is not simple and does
not follow the previous example the amount of
current used by a motor is dependent on the
load. Let’s redo the previous calculation
assuming the motor has a 10 Watt load.
Putting it together cont.
Motor Circuit
V3
R
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V1
I
V
Motor
(RM)
V2
If V is 7 Volts and R is 1 ohms and the Motor uses 10 Watts, what is I?
7 = V2 + V3
W = VI => V = W/I
7 = I + 10/I
I=2, 5
There are two answers, how can this be? As the voltage drops the motor will slow down, producing less power, reducing the need
for current - even here the motor is not linear
Application
• How do we reduce the resistance to the
motor?
– Larger Wires
– Shorter Wire runs
– Better/Fewer connections
Power Distribution
• What is Power Distribution?
– Providing power from the battery to the devices
that need it.
• Why is it important?
– Safety
– Clean distribution
• efficient and allows for better performance
• Easier modification and troubleshooting
Power Distribution
• What does it look like?
• One device or load
• What about more?
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Load
Battery (V)
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Load
Load
Power Distribution
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How is it done in FRC?
Electrical Hardware
Wiring Diagram
Control Diagram