Basic Circuit Theory Yong Heui Cho @ Mokwon University Some of slides are referred to: [1] jerbor, Circuit theory mt, slideshare, 2011.
Basic Circuit Theory
Yong Heui Cho @ Mokwon University
Some of slides are referred to:[1] jerbor, Circuit theory mt, slideshare, 2011.
2
Electronic Circuits
1. Semiconductor & Electronic Ckts2. Introduction to Smart Sensors3. Basic Circuit Theory
4. Diode – Operational Princi-ple
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Electric Circuit• An interconnection of electrical
elements.
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Charge (Q) & Current (I)• Electric current is the time rate of
change of charge, measured in am-peres (A).
• Direct Current (DC) is a current that re-mains constant with time.
• Alternating Current (AC) is a current that varies sinusoidally with time.
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Voltage (V)• Voltage (or potential difference) is the energy
required to move a unit charge through an ele-ment, measured in volts (V).
• Voltage vab between two points a and b in an electric circuit is the energy (or work) needed to move a unit charge from a to b; mathematically,
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Power & Energy• Electric power [W]– Rate at which electrical energy is
transferred by an electric circuit–DC: – AC:
• Energy [J]– – kWh: kW x hours
VIP VIP21
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timePE
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Sign Convention• Passive sign convention is satisfied when the
current enters through the positive terminal of an element and p = +vi. If the current en-ters through the negative terminal, p = −vi.
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Dependent Sources• Four possible types of dependent
sources– Voltage-Controlled Voltage Source (VCVS)– Current-Controlled Voltage Source (CCVS)– Voltage-Controlled Current Source (VCCS)– Current-Controlled Current Source (CCCS)
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Ohm’s Law• Ohm’s law states that the voltage “v”
across a resistor is directly proportional to the current “i” flowing through the resistor.
• Short circuit is a circuit element with resis-tance approaching zero.
• Open circuit is a circuit element with resis-tance approaching infinity.
IRV
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Current & Water
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Types of Resistors
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KVL• Kirchhoff Voltage Law
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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KCL• Kirchhoff Current Law
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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3 Laws for Analysis• Any circuits can be analyzed with
3 laws.–Ohm’s law– KVL– KCL– Just try and solve!
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Equivalent Resistor• Complicated resistor networks
can be replaced with one R.
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Thevenin Theorem• Developed in 1883 by M. Leon Thevenin (1857–1926), a
French telegraph engineer• Thevenin’s theorem states that a linear two-terminal
circuit can be replaced by an equivalent circuit con-sisting of a voltage source VTh in series with a resistor RTh, where VTh is the open-circuit voltage at the termi-nals and RTh is the input or equivalent resistance at the terminals when the independent sources are turned off.
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Norton Theorem• Developed by E. L. Norton, an American engineer
at Bell Telephone Laboratories in 1926, about 43 years after Thevenin published his theorem.
• Norton’s theorem states that a linear two-terminal circuit can be replaced by an equivalent circuit consisting of a current source IN in parallel with a resistor RN, where IN is the short-circuit current through the terminals and RN is the input or equiv-alent resistance at the terminals when the inde-pendent sources are turned off.
□ Courtesy to jerbor, Circuit theory mt, slideshare, 2011.
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Capacitor [F]• A component used to store elec-
tric charge CVQ
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Inductor [H]• A component used to generate
magnetic flux LI
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Impedance Z• AC resistance• Z = R + jX– Resistance (R) and reactance (X)
ZIV