T6D

Component functions and resonance

Say what rectifiers, relays, regulators, transformers, meters and ICs do, and what makes a circuit resonant.

11 pool questions1 on the exam

Syllabus: Component functions: rectifiers, relays, voltage regulators, meters, indicators, integrated circuits, transformers; Resonant circuit; Shielding

A power supply: transformer, rectifier, filter, regulator

Each stage does one job on the way from wall power to clean DC.

Rectifier: AC to DC. Regulator: steady voltage. Transformer: change the AC voltage.

Transformer changes 120 V AC to a lower AC voltage.
Rectifier (diodes) turns AC into varying DC.
Regulator holds the output voltage steady.

RememberRectifier: AC to DC. Regulator: controls the voltage. Transformer: changes the AC voltage.

A relay is a switch worked by electricity

A small current through a coil makes an electromagnet. It pulls a switch closed in a separate circuit, so a weak signal can control a big load.

The coil is an electromagnet. Its small current closes a switch in a different circuit.

RememberRelay = electrically-controlled switch.

Inductor + capacitor = a resonant circuit

Connect an inductor and a capacitor, in series or in parallel, and energy swings between them at one natural frequency. Radios use this to tune to a station.

Like a swing: energy moves back and forth at one natural rate, the resonant frequency.

RememberResonant (tuned) circuit = an inductor and a capacitor.

Shielded wire keeps unwanted signals out and in

A metal shield wrapped around a wire stops unwanted signals from coupling into it, or from its own signal leaking out to nearby circuits. It does not lower resistance or carry more current.

The shield blocks unwanted signals from coupling to the wire, or from the wire out to its neighbours.

RememberShield = prevent coupling of unwanted signals to or from the wire.

Know each part's one-line job

Part	Job
Meter	shows an electrical quantity as a number
LED	the common visual indicator (FETs and Zener diodes are not)
Integrated circuit (IC)	many transistors and parts in one package
Transistor	controls the flow of current (component 2 in figure T-1)

Memory hookIC = Integrated Circuit: a whole circuit integrated into one chip.

Loading lesson…

Go deeper

Compendium articles on the ideas in this lesson, beyond what the exam asks.

Check what stuck

Practise the 11 pool questions for this group. Answers are shuffled, and every one comes with a one-line "why".

Practise T6D →