Controls, Switches and Energy Transformation

CONTROL

The function performed by a component that can open or close a circuit

switches and pushbuttons are examples of controls

SWITCHES SINGLE POLE SWITCH OPENS/CLOSES 1

CONTACT AT A TIME DOUBLE POLE CAN OPEN/CLOSE TWO

CONTACTS AT ONCE ELECTRONS FOLLOW 1 PATH IN SINGLE

THROW SWITCH DOUBLE THROW ALLOWS ELECTRONS

TO FOLLOW 1 OF 2 PATHS P470

SWITCHES

A switch is deemed to be closed when a connection is made. If you have a closed switch you will then have a closed circuit.

Open Closed

SwitchesSwitch Number of

contacts that are open

Number of possible paths for electrons

Diagram

Single PoleSingle Throw

1 1

Single – Pole Double – Throw

1 2

Double – PoleSingle – Throw

2 1

Double – Pole Double – Throw

2 2

SWITCHES

ROCKER

SWITCH

TOGGLE SWITCH

PUSH BUTTON

MAGNETIC CONTACT

ENERGY TRANSFORMATION

CHANGE OF ONE FORM OF ENERGY TO ANOTHER FORM OF ENERGY

EXAMPLES OF ELECTRICAL COMPONENTS USED TO TRANSFORM ELECTRICITY

INCANDESCENT BULBS- NEW FORM-LUMINOUS ENERGY

HEATING ELEMENT- NEW FORM- THERMAL ENERGY

PIEZOELECTRIC CRYSTALS- NEW FORM – MECHANICAL OR SOUND ENERGY

ELECTROMAGNETS – NEW FORM OF ENERGY – MAGNETIC ENERGY

COMPONENTS WITH OTHER FUNCTIONS

CAPACITORSDIODESTRANSISTORS (AST ONLY)RELAYS (AST ONLY)

CAPACITORS CAN STORE ELECTRICAL CHARGE COMPOSED OF TWO ELECTRICAL

SURFACES SEPARATED BY AN INSULATOR (BLOCKS THE FLOW OF ELECTRONS)

CHARGE BUILDS UP ON ONE PLATE, INSULATOR IS REMOVED AND CHARGE IS RELEASED ALMOST INSTANTLY

CAPACITORS

- +

-------

++++++

Plate

• The left part of the plate attracts all the electrons.

• The right side of the plate is positively charged as the power supply attracts all the electrons.

• This plate stops the flowof electrons, but at the same time the capacitorstores a charge.

• Once the capacitor is pushed out of the way and electricity can flow, you will have a strong charge that will happen in a short period of time.

Dielectric

CAPACITOR CHARGE FROM CAMERA

BATTERY BUILDS UP UNTIL BUTTON IS PRESSED

FULL CHARGE

IS RELEASED IN

THE FLASH

DIODE ALLOWS ELECTRIC CURRENT TO FLOW

IN ONE DIRECTION MADE OF SEMICONDUCTOR PROTECTS ELECTRONIC PARTS FROM

HAVING ELECTRONS FLOW IN THE WRONG DIRECTION – NOTABLY WHEN A BATTERY (IS INCERTED IN THE WRONG WAY) OR POWER SUPPLY IS PUSHING ELECTRONS THE WRONG DIRECTION

DIODE USED TO CONVERT AC TO DC

LED’S ARE ‘LIGHT EMITTING DIODES’ THAT GIVE OFF LIGHT WHEN CURRENT FLOWS THROUGH THEM

TRANSISTORS (AST ONLY)BLOCK OR AMPLIFY AN

ELECTRIC CURRENT

TRANSISTORS (AST ONLY) CURRENT FLOWS FROM

COLLECTOR TO EMITTER TO BASE BASE ACTS LIKE A VALVE THAT

ALLOWS CURRENT TO FLOW FREELY; BLOCK FLOW OR ALLOW SOMEWHERE IN BETWEEN

CONNECTION BETWEEN TRANSISTORS AND COMPUTERS P477 OF OBSERVATORY

RELAYS (AST ONLY) A RELAY OPENS OR CLOSES A

CIRCUIT USING AN ELECTRICAL SIGNAL FROM ANOTHER CIRCUIT (THINK RELAY RACE-PASSING ON)

RELAYS (AST ONLY) COMMONLY USED TO CONTROL HIGH

VOLTAGE CIRCUITS FROM A REMOTE DISTANCE, HEATING SYSTEMS,

LIGHTING IN A THEATRE, HIGH VOLTAGE APPLIANCES (X-RAY MACHINE)