Systems 3/4 - Electronics 1

Units - what is the measurement (from the calculation sheet) and base units name?

1. V / V (answer: Voltage in Volts)

2. I / A

3. P / W

4. R / Ω

5. E (or W) / J

6. N / (no base unit - in a calculation with voltage)

7. C / F

1. Voltage in Volts

2. Current in Amps

3. Power in Watts

4. Resistance in Ohms

5. Energy (or Work) in Joules

6. Number of turns (of a coil in a transformer)

7. Capacitance in Farads

PCB

1. What does it stand for?

2. What is it used for? What are the identifying features?

1. Printed Circuit Board

2. Mechanically support and electrically connect electronic components using conductive pathways (traces)

Surface mount (SMT)

1. Definition

2. Why use this?

1. A component that lays flat on the surface of a circuit board, with no protruding pins or leads.

2. Easy for machines to produce

Breadboard

1. Definition

2. Why use this?

1. Rows of electrically connected holes in a board that jumper cables plug into

2. Easy to use for quick prototyping

Veroboard

1. Definition

2. Why use this?

1. A grid of through holes (donut holes) that are often electrically connected in rows

2. Allows for soldering components by hand for better attachment than a breadboard.

1. What happens to current in series components?

2. What happens to current in parallel?

1. It stays constant through the circuit (All electrons pass through)

2. Shared/splits between branches (as a ratio of resistance)

1. Conductor (definition)

2. Insulator (definition)

1. A material that allows electrons to move through it easily

2. A material that does not allow electrons to move through it easily

Multimeter - voltage

1. Steps to use?

2. Use case

1. Set the meter to the V with flat lines symbol, typically to the 20, probes placed parallel to component

2. To test voltage drop on component, or to test battery charge

Multimeter - current

1. Steps to use?

2. Use case

1. Set the meter to the A with flat lines symbol, the red probe needs to be on the 10A plug and set the dial to the highest setting, place the probes in series (break the circuit), a tiny reading will appear, then switch the plug back and change the dial one notch lower (bold is what is normally asked in the exam)

2. To typically test total current

(Rare)

Multimeter - continuity

1. Steps to use?

2. Why is this useful?

1. Set the meter to the arrow (diode) symbol, probes placed on opposite ends of component/wire being tested

2. Checks for conductive path (checking solders)

Solenoid

1. Description

2. Use case

3. Diagram symbol (lots of versions out there)

1. A coil of wire (inductor) around a metal rod which is pushed/pulled when a current passes through the wires

2. Electric door lock

Relay

1. Description

2. Use case

3. Diagram symbol (lots of versions out there)

1. Is an electromagnet next to a mechanical switch

2. Used to electrically complete another (often high-power) circuit

Brushed DC Motor

1. Description

2. Pros/Cons (compared to brushless)

3. Diagram symbol (two acceptable versions)

1. Convert electrical energy into kinetic energy through induction of a rotary coil which is connected to a split ring/brushes

2. Simpler, cheaper, less efficient, less powerful

Brushless DC Motor

1. Description

2. Use case

3. Diagram (internals)

1. The stator and rotor don’t touch (no brush). Needs a signal wire to activate pairs of coils (stator) for speed. Gets the right alignment of magnets with hall effect sensors (mag sensors).

2. Drones (high power/weight)

AC induction motor

1. Description

2. Use case

3. Diagram (internals)

1. Produce motion from 3-phase Alternating current (looks similar to brushless, unless shown in 3D with squirrel cage)

2. Used for simple, high efficiency, high-power applications like factories (needs mains power)

Servo

1. Description

2. Use case

1. Motor with precise angular position control. Controls position with 3rd signal wire

2. RC car turning, RC plane flaps adjustment

Stepper Motor

1. Description

2. Use case

3. (rare + tough) Diagram (internals)

1. A very angularly precise, high torque motor that can move in very small increments (eg: 1.2°)

2. 3D printer, Lasercutter

Generator/ dynamo

1. Description

2. Use case

1. A motor that converts mechanical energy into AC electrical energy (AC induction motor)

2. Power generation plants

(rare)
Flyback Diode

1. Description/ use case

2. Circuit diagram setup

1. Diode connected across any inductor (eg: motor) to prevent damage from excessive voltage discharge (motor still spinning after turned off).

Speaker

1. Description

2. Diagram symbol

Converts electrical signals into sound with electromagnet and diaphragm

Microphone

1. Description

2. Diagram symbol

Reverse of speaker. Sound pushes on diaphragm causing electrical signal

Piezo Buzzer

1. Description

2. Diagram symbol

1. Makes a predictable buzzing sound with electrical current applied to a specific crystal (NOT A SPEAKER)

Transformer

1. AC or DC?

2. Description

3. What kind of transformer terms are associated with an exam question?

4. Use case

5. Diagram symbol

1. AC only

2. Steps up or down voltage (current inversely) by the ratio of coils on each side (turns or number)

3. Primary coil 1000, secondary 500, 2:1, V1 = 230V, then V2 = 115V

4. Voltage is stepped up for transmission from powerplants, and stepped down once it arrives for homes

Full bridge rectifier

1. Description

2. Use case

3. Commonly added components? (3)

4. Circuit diagram setup

1. Made up of 4 diodes as in diagram

2. Used to convert AC to DC voltage

3. Transformer for step down AC, capacitor for smoothing, reverse bias Zener diode for clamping voltage

1. What is this and how is it different from a full bridge rectifier

2. What does the middle wire that splits the turns do?

3. How do you count the turns for the transformer?

1. It’s a simpler rectifier

2. Its the common ground, where the rectified DC always goes back to

3. The output turns are in two halves - one does positive voltage and the other does negative voltage, so you only have to count either the top or bottom

Fuse

1. Description

2. Use case

3. Diagram symbol

1. Thin covered wire that melts at a specific current level

2. Use in high-power circuits to protect delicate components.

Potentiometer

1. Description

2. Use case

3. Diagram symbol

1. A three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider

2. Volume control

LDR

1. What it stands for

2. Description

3. Use case

4. Diagram symbol

1. Light Dependent Resistor

2. Changes resistance depending on the light intensity that falls upon it

3. Light sensor in a room

Thermistor

1. Description

2. Use case

3. Diagram symbol

1. A resistor that changes its resistance with a change of temperature

2. Temp control in a room

3. (Look out for the flick at the end of the diagonal line)

(rare)
Photo transistor

1. Description

2. Diagram symbol

1. A component that electronically switches (or amplification) which relies on exposure to light to operate