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Electrical Parts, Controls, and Devices
Home appliances use circuit control and safety devices as well as resistance loads to make our lives considerably easier. A simple understanding of the function and appearance of the electrical parts used in appliances, as well as the wire diagram symbols used to portray their use will give you a huge advantage in troubleshooting and repairing your home appliance problems. It may seem a little overwhelming at first...Start with an aspirin and the electricity 101 video and I think you'll feel a little better.
Transducer | Thermostat | Thermistor | Light Dependent Resistor | Motor | Coil / Solenoid | Buzzer | Fuse | Resistor | Heater | Lamp | Rheostat | Potentiometer | Timer | Transformer | Diode Capacitor | Ground | Switches
Lamp: 
A lamp is a resistor-transducer, which converts electrical energy to light.
Rheostat: 
Rheostats are variable resistors have 2 contacts and are usually used to control current. Rheostats can be used to regulate electric range surface burners, among other applications. (The third teminal in this rheostat picture is a grounding terminal.)
Potentiometer: 
Potentiometers are variable resistors have 3 contacts and are usually used to control voltage.
Timer:
Timers are used in most appliances to control the timing of a particular action. A timer can be motor operated or a solid-state control board. As the timer advances, one ore more switches are opened or closed to energizing or breaking electrical contact to a particular part at the correct time.
Transformer:
Transformers are wo coils of wire linked usualy by an iron core. Energy is transferred between the coils by the magnetic field in the core. Transformers are used to step up (increase) and step down (decrease) AC voltages. For example a transformer may be supplied with 110 volts AC and produce a voltage of 3 VAC or 2000 VAC. A transformer does not generate electricity it increases or decreases a circut's voltage.
Diode: 
A diode is an electrical device that only allows current to flow in one direction, like a one way gate. In a microwave oven diodes are used in line with a transformer and capacitor to create a large voltage discharge used by the microwave's magnetron to create the microwaves used to excite the water in your food.
Capacitor: 
A capacitor stores an electric charge. (It is important to note that that electrical charge can remain even after a circuit’s power supply has been removed or unplugged.)
Ground or Earth Connection
This connection is very important; it is usually made with bare wire attached to the cabinet of an appliance, which is in turn connected to earth within the service panel of your home through a “grounded” plug. This connection serves a safety protecting against electrocution in the case of a short.
Switches:
Terms describing switch properties
Open:
Off position, offering infinite resistance to a circuit.
Closed:
On position, offering zero resistance to a circuit.
Pole:
Number of contact sets.
Throw:
Number of conducting positions. (Single or double)
Way:
Number of conducting positions. (Three or more)
Momentary:
A switch that returns to its normal position when released.
Types of switches
On-Off Switch SPST (Single Pole, Single Throw):
An on-off switch allows current to flow only when it is in the closed or on position.
2-Way Switch SPDT (Single Pole Double Throw): 
A 2-way switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position.
Relay: 
A relay is an electrically operated switch, commonly used in appliance control boards.
Pressure sensing switch: 
This style of switch has a pressure sensing mechanism inside it, usually a diaphragm, which flexes as pressure increases and opens or closes a switch as the pressure reaches a specific level. These switches are commonly used in washing machines to sense the amount of water that has entered the washtub and prevent overflow.
Push to Make Switch: 
A push to make switch allows current to flow when the switch is pressed.
Push to Break Switch: 
This type of push switch is normally closed (on) it is open (off) only when the button is pressed.
Dual On-Off Switch DPST (Double Pole Single Throw):
A dual on-off switch.
Reversing Switch DPDT (Double Pole Double Throw):
This switch can be used to change the direction of a motor.
