Basic Electrical and Electronic Circuits

The first thing a beginner needs to know to understand a system of electrical circuits and electronic circuits is the understanding of basic electrical theory including electron and basic unit of electrical measurement such as the value of current, the value of voltage, and the value electrical power; the introduction of codes and electric and electronic symbols; understanding of basic electric and electronic formulas; understanding of basic electrical circuits and electronics; and ways of working components.

In principle, the basic electrical circuit consists of three parts:

1. Voltage source: Voltage source (Power Supply) can be either voltage AC (Alternate Current) 220-240 VAC from the power company or a DC voltage (Direct Current) like an Accumulator (Battery Cell)
2. Conductor: Conductor can be a cooper wire, cable, or other objects that are conductive.
3. Load:  Load can be either electric or electronic devices such as televisions, refrigerators, washing machines, computers, electric motors, radios, lamps, LEDs, etc.

The third part of the electrical circuit can be connected or disconnected by a switch. When the switch is closed, electric current will flow from the source voltage through the load so that the load will work, and will be disconnected when the switch is open (disconnect) to turn off the load.

If the resistance of the conductor ignored or considered to be zero (0 Ohm). The greater voltage source, the greater current flowing to the load. The larger the load resistance, the smaller current flowing in the electrical circuit. In this condition shall apply Ohm's Law.

Ohm's law is a statement that the electrical current flowing through a conductor is always proportional to the applied potential difference to it. A conductive object will be in accordance with Ohm's law if the resistance value does not depend on the value and polarity of the potential difference. Although this statement does not necessarily apply to all types of conductors, but the term "law" still used by historical reasons.

Mathematically Ohm's law written by the equation:

"I" is electric current flowing in a conductor in Amperes (A), "V" is the voltage present at both ends of the conductor in Volts (V), and "R" is the resistance contained in a conductor in Ohm . This law was initiated by George Simon Ohm, a physicist from Germany in 1825 and published in a paper titled The Galvanic Circuit Investigated Mathematically in 1827. (Wikipedia)

Resistance, Voltage, and Current

The meaning of Resistance, Voltage, and Current
To understand the voltage and ampere we can see the example of two glasses are placed in different positions (left image). Glass "A" at the top position and glass "B" in the lower position. Glass "A" and glass "B" is connected with the pipe and in glass "A" attached faucet and filled with some water.

If the faucet is opened, the water will flows from glass "A" to the glass "B" through the pipe. The amount of water current that flows depends on the difference in height between the two glasses and depends on the size of the facet opening. The greater the difference in height between the two glasses, the greater the flow of water flowing through the pipe.

This height difference is assumed as the voltage where glass "A" is the positive pole and glass "B" is the negative pole. Pipe is assumed to be the connecting cables (connectors) and faucet as a switch. If the faucet is closed, the water will not flow through the pipe but if the faucet is opened, the water will flow from glass "A" to the glass "B" through the pipe.

The above example applies also to the electric current, if the switch is disconnected, the electric current will not flow but if the switch is connected, the electric current will flow from the positive pole toward the negative pole through the cable (the connector).

Unit voltage is Volt (V) and the unit of electrical current is Amperes (A). The value of the current that flows influenced by the value of the resistance in an electrical system or a in electronic circuits. Resistance can be assumed by the size of the pipe or the size of the opening faucet. Resistance unit is Ohm.

Voltage is the cause and current is the effect 
Voltage is the source to make the current flows and current will flow if the circuit is complete, meaning there are voltage source, connector, and the load. 

Note the electronic circuits above. In the picture "A", there are a voltage source, connector, and the load but no current flows because the switch is open; In picture "B" there are a voltage source, connector, and the load and the conditions of switch  is closed so the current will flow from the positive pole to negative pole through connector; In picture "C" there will be no current flowing though there are connector, the switch is closed, and the load, but there is no voltage source.

Electric and Electronic Symbols

Before studying the electrical and electronic, the things we should know are electrical and electronic symbols to learn more easily, especially when reading circuits and electrical schematics and electronics in a system.

By using these symbols, schematics will be easily constructed and easily understood so that the assembly process would be much easier. Below are some symbols of electrical components and electronic components.

Usually a professional electrician will read electrical schematics before the installation process. Besides the application of electrical symbols and electronic symbols can help finding an error or fault during the repair time.

SYMBOL	COMPONENT	NOTE
Connections
	Cable Connection	Connected wire (conductor)
	Connected Cable	Connected
	Disconnected Cable	Disconnected
Switch and Relays
	Toggle Switch SPST	Disconnect when open
	Toggle Switch SPDT	One on - one off
	Switch Push-Button (NO)	Connect when the button is pushed
	Switch Push-Button (NC)	Disconnect when the button is pushed
	DIP Switch	Multiswitch
	Relay SPST	Connection (Open and Close) by electromagnetic
	Relay SPDT
	Jumper	Connected by jumper
	Solder Bridge	Connected by soldered
Ground (GND)
	Earth Ground	Zero reference
	Chassis Ground	Body (Chassis) Ground
	Common/ Digital Ground
Resistor Symbols
	Resistor	Resistor
	Resistor
	Potensio Meter	Variable Resistor
	Potensio Meter
	Variable Resistor	Variable Resistor
	Variable Resistor
Condensator Symbols
	Bipolar Condensator	Condensator
	Nonpolar Condensator
	Bipolar Condensator	Electrolytic Condensator (ELCO)
	Bipolar Capacitor	Electrolytic Condensator (ELCO)
	Kapasitor Variable	Condensator yang nilai kapasitansinya dapat diatur
Inductor Symbols
	Inductor, spul, coil	Generate electromagnetic
	Induktor dengan inti besi	Generate electromagnetic
	Variable Inductor	Variable Inductor
Power Supply
	DC Source	Generate DC Voltage Source
	Current Source	Menghasilkan sumber arus tetap
	AC Source	Generate AC Voltage Source
	Generator	Generate Electric Voltage
	Battery	Generate DC Voltage
	Multicell Battery	Generate DC Voltage
	Variavle Source Voltage	Voltage Source
	Variable Current Source	Current Source
Meter Symbols
	Volt Meter	Measure voltage
	Ampere Meter	Measure Current
	Ohm Meter	Measure Resistance
	Watt Metter	Measure Electrical Power
Lamp Symbols
	Lamp	Produce light when electrified
	Lamp
	Lamp
Diode Symbols
	Diode	Serves as a rectifier of electrical current that can flow in one direction (forward biased)
	Zener Diode	DC Voltage stabilizer
	Schottky Diode	Diode with low drop voltage, typically found in logic ICs
	Varactor Diode	Varactor
	Tunnel Diode	Tunnel Diode
	LED (Light Emitting Diode)	Produce light when electrified DC in one direction
	Photo Diode	Generate electric current when it gets light
Transistor Symbol
	Bipolar NPN Transitor	The electrical current will flow (EC) when the base (B) given a positive
	Bipolar PNP Transistor	The electrical current will flow (CE) when the base (B) were given negative
	Darlington Transitor	The combination of the two bipolar transistors to increase the reinforcement
	JFET-N Transistor	Field Effect Transistor N channel
	JFET-P Transistor	P channel Field Effect Transistor
	NMOS Transistor	N channel MOSFET transistor
	PMOS Transistor	P channel MOSFET transistor
Other Symbols
	Motor	Electric Motor
	Transformer, Transformator	Step-Up and Step-Down Voltage
	Electric Bell	Sounds when electrified
	Buzzer	Producing sound as electrified buzz
	Fuse	Safety. Will disconnect when the current exceeds the capacity
	Fuse
	Bus	Consists of many lines of data or address lines
	Bus
	Bus
	Opto Coupler	As with insulation between two different settings. Connected by light
	Speaker	Transform electrical signals into sounds
	Mic, Microphone	Change the voice signal into an electric current
	Op-Amp, Operational Amplifier	Amplifier input signal
	Schmitt Trigger	Reduce noise
	ADC, Analog to Digital	Change the analog signal into digital data
	DAC, Digital to Analog	Converts the digital data into analog signals
	Crystal, Ocsilator	Producing pulses
Antenna Symbols
	Antenna	Radio signal transmitters and receivers
	Antenna
	Dipole Antenna	The combination of simple Antenna
Logic Symbols
	NOT Gate	The output will be the inverse input
	AND Gate	Output will be 0 if one of input 0
	NAND Gate	The output will be 1 if one input 0
	OR Gate	The output will be 1 if one input 1
	NOR Gate	Output will be 0 if one input 1
	EX-OR Gate	Output will be 0 if the input is equal
	D-Flip-Flop	Can serve as data storage (memory)
	Multiplexer 2 to 1	Selecting one of the input data to be sent to the output
	Multiplexer 4 to 1
	D-Multiplexer 1 to 4	Selecting the input data to be sent to one output