# Basic Electronics.

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Basic Electronics

Electric Circuit Components are connected together with electrical wire to form a closed loop. Components are represented by symbols

Electric Circuit Electrical wire used to connect components is a conductor. A conductor allows electric current to flow through it easily. Good conductors include: copper, gold, silver, tin Copper wire is generally used as it is most cost effective. All electrical wires have a plastic cover. Plastic is an insulator. An insulator does not allow current to flow through it. Avoids electric shock. Insulators include: plastic, glass, wood

Electric Circuit Electric Current is the flow of electrons around a circuit. Electrons have a negative charge

Electric Circuit Electric current is measured with an Ammeter
The ammeter is placed into the circuit (in series) Unit of measurement is the Ampere or ‘amp’ Represented by the letter I

Electric Circuit EMF (electromotive force) is the force that makes electrons flow around a circuit. EMF is often called Voltage and is provided by the battery. Higher voltage = more current

Electric Circuit Voltage is measured using a Voltmeter.
The voltmeter is placed across a component (in parallel) Unit of measurement is the Volt. Represented by letter V.

Electric Circuit Resistance is the opposition to the flow of electric current. All components have resistance. Electrical wire has resistance. Unit of measurement is the Ohm (Ω) Represented by the letter R

Electric Circuit Resistance is the opposition to the flow of electric current. All components have resistance. Electrical wire has resistance. Unit of measurement is the Ohm (Ω) Represented by the letter R

Ohm’s Law Voltage , Current & Resistance are calculated using Ohm’s Law V I R

Series Circuit Components are connected one after the other
There is only one path for current to flow around

Series Circuit The current at all points in a series circuit is equal

Series Circuit The voltage is shared between the components in a series circuit. Components of equal resistance – voltage is shared equally

Series Circuit The voltage is shared between the components in a series circuit. Components of unequal resistance – voltage is shared proportionally

Parallel Circuit Components are connected side by side
There is more than one path for current to flow around

Parallel Circuit The voltage across each path is always the same as the applied voltage When component resistance in each path is the same

Parallel Circuit The voltage across each path is always the same as the applied voltage When component resistance in each path is different

Parallel Circuit The voltage across each path is always the same as the applied voltage When there is more than one component in a path

Parallel Circuit The current is divided between the paths proportionally (Ohm’s Law)

Motor Control SPST Switch:
Polarity connection determines direction of rotation

Motor Control DPDT Switch: Forward and reverse control of motor

Motor Control DPDT Switch +V C3 C4 C1 0V C2

Motor Control DPDT Switch: Wiring Diagram

Motor Control DPDT Switch: Wiring Diagram

Motor Control DPDT Switch: Wiring Diagram

Motor Control DPDT Switch: Wiring Diagram +V 0V

Motor Control Forward and reverse control of motor with limit switches

Motor Control Forward and reverse control of motor with limit switches
Wiring Diagram +V 0V

Motor Control Forward and reverse control of motor with limit switches

Motor Control Forward and reverse control of motor with limit switches
Wiring Diagram +V 0V

Motor Control Will SW1 and SW2 act as limit switches in this circuit?

Sensors Light Dependent Resistor (LDR)
Resistance increases as darkness increases

Sensors Thermistor Resistance decreases as the temperature increases

Transistor Acts as a switch
Voltage > 0.6V-0.7V between the base and emitter transistor is on Collector Emitter Base BFY51 E B C

Transistor Voltage Divider circuit is used to create the turn on voltage between the base and emitter.

LDR Transistor Circuit
An LDR changes the voltage according to light levels Dark = LED on

Relay A relay is a switch used to turn other circuits on and off
Coil terminals are part of controlling circuit DPDT switch

Relay Position A

Relay Position A NC1 NO2 P1

Relay Position B

Relay Position B NO2 NC2 P2

Relay