Electronic Devices and Circuits Engineering Sciences 154

Also see valuable references and interactive web pages at Links to Electronics Tutorials.

Sources and Signals:

Symbol Representations of "Ideal" Sources

"Ideal" Voltage Source

"Ideal" Current Source

Temporal Representations of Electronic Signals:

DC or "Step" Signal
Low Frequency Sinusoidal Signal	High Frequency Sinusoidal Signal
Amplitude Modulated (Analog) Signal	Frequency Modulated (Analog) Signal
Real Analog Signal - Video Luminosity
Real Analog Signal - Bat Sonar
Idealized Digital Signal	Real Digital Signal (click to enlarge)
Amplitude Modulated Digital Signal	Frequency Modulated Digital Signal

Spectral Representations of Electronic Signals:

 

Jean Baptiste Joseph Fourier (1768 - 1830) - source

A key question in information technology:

With such a vast array of complex signals possible, how can one ever expect to obtain a quantitative understanding of the information content of messages or to understand how signals are transformed in passing through physical system?  Spectral analysis gives us the tools to achieve just such a quantitative understanding.

The basic idea is that any time varying signal -- no matter how complex-- can be represented as a sum (or integral) of sinusoidal components - a spectral representation.

Does this help?

Yes.

We shall see that a particular measure of the complexity of an spectral representation -- viz., the "bandwidth" -- directly relates to the information content of the message.  However, before we can appreciate the notions of spectral (Fourier) analysis or decomposition, we first lightly explore the subject of spectral (Fourier) synthesis.

Once over lightly on Spectral Synthesis:

Fourier Recipe

Fourier Synthesis: a nice spectral applet from the Physics Department at Georgia Tech: one of many collected at Links to Electronics Tutorials.

 

See horrible network no. 1 and horrible network no. 2

Goal of circuit analysis is to turn this problem into a related problem in linear algebra - viz.

	h-parameter representation
	y-parameter representation
	z-parameter representation
	g-parameter representation

Resistive Networks:

In 1827 what is now known as Ohm's law appeared in Die galvanische Kette, mathematisch bearbeitet. Between 1825-27, Georg Simon Ohm (1789-1854), professor of mathematics at the Jesuit College of Cologne, had been studying electrical conduction following as a model Fourier's study of heat conduction.   Ohm's Law states that the strength of an unvarying electric current is directly proportional to the electromotive force, and inversely proportional to the resistance of the circuit concerned. Need it be said, the unit of resistance is named after him. (Source 1 and Source 2)

Simplest and most important examples - Divider Networks
 

Linear Circuit Elements

Circuit Symbol	Physical Law	Impedance
Pictures of real resistors
Pictures of real capacitors
Pictures of real inductors


 
• Simple RC Circuits by straight forward methods

 
• Simple RC and RLC by "phasor" transform method

 
• Simple RLC Circuits by Laplace transforms