Bre's Starter Electronics

Resistor

An electronic component that limits the flow of electric current.

Resistance

Opposition to the flow of electric current, measured in ohms.

Current

The flow of electric charge through a circuit.

Voltage

Electrical pressure that drives current through a circuit.

Water analogy

Compares voltage to water pressure and current to water flow.

Carbon film resistor

A common resistor made from a carbon coating on a ceramic tube.

Metal film resistor

A resistor with a metal coating that offers better precision than carbon film types.

Wire wound resistor

A resistor made from resistive wire for high-power applications.

Resistor construction

A ceramic core coated with resistive material and trimmed with a spiral cut to achieve the desired resistance.

Spiral cut

Increases resistance by creating a longer, narrower conductive path.

LED current limiting

A resistor is placed in series with an LED to prevent excessive current.

Series connection

Components connected in a single path so the same current flows through all.

Variable resistor

A resistor whose resistance can be adjusted with a movable wiper.

Potentiometer

A common type of variable resistor used to adjust voltage or resistance.

Timing circuit

A resistor charging a capacitor creates a predictable time delay.

Capacitor

A component that stores electrical charge between two conductive plates separated by an insulator.

Capacitor function

Stores energy and releases it when needed.

Dielectric

The insulating material between a capacitor's conductive plates.

Capacitor water analogy

A flexible diaphragm that stores pressure without allowing direct flow.

Charge storage

The ability of a capacitor to hold electrical energy.

AC capacitor operation

Allows alternating current to pass by repeated charging and discharging.

Capacitance

The ability of a capacitor to store electric charge.

Farad

The unit of capacitance.

Nanofarad (nF)

One billionth of a farad.

Microfarad (µF)

One millionth of a farad.

Capacitance factors

Determby plate area and dielectric thickness.

Larger plate area

Increases capacitance.

Thinner dielectric

Increases capacitance.

Multilayer capacitor

Uses many stacked conductive layers to increase capacitance.

Ceramic capacitor

Uses ceramic as the dielectric and is common for low to medium capacitance values.

Metallized film capacitor

Uses metallized plastic film rolled into a compact cylinder.

Voltage rating

The maximum voltage a capacitor or component can safely withstand.

High-voltage capacitor

Requires a thicker dielectric to prevent breakdown.

Electrolytic capacitor

A polarized capacitor with high capacitance using a liquid electrolyte.

Electrolyte

Conductive liquid used inside electrolytic capacitors.

Oxide layer

Extremely thin insulating layer formed on aluminum foil in electrolytic capacitors.

Polarized capacitor

A capacitor that must be connected with the correct polarity.

Equivalent Series Resistance (ESR)

Internal resistance that affects capacitor performance.

Electrolytic capacitor aging

Electrolyte dries out over time, increasing ESR.

Power supply smoothing

Large capacitors reduce ripple in rectified DC supplies.

Ripple voltage

Remaining AC variation on a DC power supply.

Rectification

Conversion of AC into DC.

Switch mode power supply

High-frequency power supply that places greater stress on capacitors.

Safety vent

Pressure relief feature on electrolytic capacitors to prevent explosion.

Reverse polarity

Connecting a polarized component backwards, potentially causing failure.

Capacitor failure

May bulge, vent, or explode when damaged or connected incorrectly.

Diode

A semiconductor device that allows current to flow in only one direction.

Anode

Positive side of a diode where current enters.

Cathode

Negative side of a diode where current exits.

One-way current flow

The primary function of a diode.

Signal diode

A small diode designed for low-current signal applications.

Rectifier diode

A diode designed to handle higher currents for power rectification.

1N4148

A common small-signal diode.

1N4007

A common 1-amp rectifier diode rated for high reverse voltage.

Peak Inverse Voltage (PIV)

Maximum reverse voltage a diode can withstand without conducting.

Forward voltage drop

Voltage lost across a conducting diode, typically about 0.6 V for silicon.

Silicon diode

Standard diode with a forward voltage drop of approximately 0.6 V.

Schottky diode

A diode with a lower forward voltage drop, improving efficiency.

Light Emitting Diode (LED)

A diode that emits light when forward biased.

Forward bias

Applying voltage so current flows through a diode normally.

Reverse bias

Applying voltage opposite the normal conducting direction.

LED reverse voltage

Usually limited to about 5 volts.

Vintage LED

Early LED packaged similarly to glass signal diodes.

Zener diode

A diode designed to regulate voltage in reverse bias.

Voltage regulation

Maintaining a constant output voltage.

Voltage reference

A stable reference voltage provided by devices like Zener diodes.

Transistor

A semiconductor device used for switching or amplification.

NPN transistor

A transistor commonly used for low-side switching.

Base

The transistor terminal that controls conduction.

Collector

The transistor terminal through which load current enters.

Emitter

The transistor terminal through which current exits.

Transistor switch

Uses a small base current to control a larger collector current.

Transistor amplifier

Uses a small input signal to control a larger output signal.

Current gain

Ratio of collector current to base current.

Gain (β or hFE)

The amplification factor of a transistor.

BC547

A common general-purpose NPN transistor.

2N3904

A common NPN transistor widely used in North America.

MOSFET

A transistor optimized for efficient switching with very low on-resistance.

Gate

Control terminal of a MOSFET.

On-state resistance

Resistance of a MOSFET when fully switched on.

High-current switching

A strength of MOSFETs due to low power loss.

IGBT

Insulated Gate Bipolar Transistor combining MOSFET control with bipolar power handling.

Insulated Gate Bipolar Transistor

High-power transistor combining easy gate drive with high current capability.

Ohm's Law

Relationship between voltage, current, and resistance.

Ohm's Law formula

V = I × R.

Resistance formula

R = V ÷ I.

Current formula

I = V ÷ R.

Voltage formula

I = V × R.

Resistance unit

Ohm (Ω).

Current unit

Ampere (A).

Voltage unit

Volt (V).

Milliamp (mA)

One thousandth of an ampere.

Example LED calculation

Three 2 V LEDs on a 12 V supply leave 6 V across the resistor.

600-ohm resistor example

Required to limit current to 10 mA with a 6 V drop.

Standard resistor values

Actual resistor values are selected from preferred standard sizes.

Measuring current with Ohm's Law

Measure voltage across a known resistor and calculate current.

330-ohm resistor example

5 V across 330 Ω equals approximately 15 mA.

Resistor power rating

Maximum power a resistor can safely dissipate.

Power dissipation

Conversion of electrical energy into heat.

Resistor overload

Excessive power causes overheating, smoke, or failure.