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Fundamentally So... Archive
Fundamentally So... are quick encapsulated reviews of engineering fundamentals, with
a little history thrown in for fun.
These are not meant to be comprehensive discussions, but an introduction to
select basic topics for new designers, or a quick review for working designers.
FS06 Millmans's Theorem
Millman's Theorem states: The node voltage of a network of parallel branches,
each consisting of a voltage source and a conductance in
series (Fig 1), can be calculated by the formula:
V0 = (G1V1+ G2V2 + ... + GNVN)
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(G1 + G2 + ... + GN)
FS05 Nortons's Theorem
Norton's Theorem states that any linear combination of voltage and current
sources and resistances can be replaced by a single ideal current source Ig and a
single parallel resistor Rg.
Norton equivalent circuits are transformations of
Thevenin equivalent circuit - if you know either equivalent, the other is
easily derived.
FS04 Thevenin's Theorem
Thevenin theorem states that any linear combination of voltage and current
sources and resistances can be replaced by a single voltage source Vg and a single
series resistor Rg. Using a Thevenin equivalent to replace a complex circuit can
greatly simply circuit analysis.
FS03 Wheatstone's Bridge
Though not actually invented by Charles Wheatstone, the circuit element arrangement named
after him, the "Wheatstone Bridge," is a staple in instrumentation and sensor designs.
The Wheatstone bridge can be used to measure an unknown resistance, inductance or
capacitance, and is widely used for strain gage measurements.
FS02 Kirchoff's Laws
Kirchoff's observations and deductions led to the method of calculation of current,
voltage and resistance in electrical circuits with multiple loops.
FS01 Ohm's Law
Ohm's Law defines the relationships between (P) power, (E) voltage,
(I) current, and (R) resistance.
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