Interactive familiarization with resistors, capacitors, inductors, diodes, LEDs, transistors, multimeters, and breadboards.
Interactive Resistor — Change bands to calculate value
1st Digit
2nd Digit
3rd Digit
Multiplier
Tolerance
1.00 kΩ ± 5%Range: 950 Ω — 1.05 kΩ
Knowledge — Resistor
What is a Resistor?
A passive two-terminal component that opposes current flow. The ratio of voltage to current defines its resistance. Used for current limiting, voltage division, and biasing active components.
V = I × R | P = I² × R
Reading 5-Band Color Codes
Bands 1–3 are digits, Band 4 is multiplier, Band 5 is tolerance
Read left to right; gold/silver band is always on the right
Tolerance shows how much the actual value may deviate
Power rating (¼W, ½W, 1W) limits maximum safe heat dissipation
A passive component that stores electrical energy in an electric field between two conductive plates separated by a dielectric. Charges when connected to voltage, discharges when disconnected.
A passive component that stores energy in a magnetic field when current flows through it. Resists changes in current (Lenz's Law). Consists of a coil of wire, often wound around a magnetic core to increase inductance.
V = L × (dI/dt) | XL = 2πfL
Key Properties
Measured in Henrys (H); practical: mH (10⁻³), µH (10⁻⁶)
Short circuit to DC steady-state; blocks high-frequency AC
Reactance (XL) increases with frequency — opposite of capacitor
Iron/ferrite core multiplies inductance by µᵣ (permeability)
Used in: power supply filters, RF chokes, LC oscillators, transformers
Mutual inductance between two coils is the principle of transformers
PN Junction Diode — Bias Simulator
⚡ Forward Bias
🚫 Reverse Bias
Supply Voltage5.0V
Diode Type
0.7V
Voltage Drop (Vf)
4.3V
Output Voltage
⚡ Forward Biased — Current flows freely
Knowledge — PN Junction Diode
What is a Diode?
A semiconductor device with a P-N junction that allows current to flow in one direction only. When forward biased (anode + > cathode −), current flows; when reverse biased, only negligible leakage current passes.
I = Is(e^(V/VT) − 1) [Shockley Equation]
Types of Diodes
Rectifier Diode: Converts AC to DC — core of power supplies
Zener Diode: Voltage regulation via controlled reverse breakdown
Schottky Diode: Very fast switching, low forward voltage (~0.2V)
LED: Emits light when forward biased (see LED tab)
Photodiode: Generates current proportional to incident light
Varactor: Variable capacitance diode used in RF tuning circuits
LED — Interactive Color & Power Tester
● ON
LED OFF
1.6–2.0V
Forward Voltage
610–760 nm
Wavelength
Knowledge — LED
How does an LED work?
A Light Emitting Diode converts electrical energy directly into light via electroluminescence. When electrons recombine with holes across the P-N junction, they release energy as photons. The photon color depends on the semiconductor bandgap energy.
E = hf = hc/λ (Photon Energy)
Circuit Rules
Longer lead = Anode (+), Shorter lead = Cathode (−)
Always use current-limiting resistor: R = (Vs − Vf) / If
Typical current: 10–20 mA for standard indicator LEDs
Color determines forward voltage drop (see material table below)
White LEDs use a blue InGaN chip + yellow YAG phosphor coating
💡 Active LED: AlGaAs, GaAsP — Red, 610–760 nm
LED Color — Material Composition & Specifications
Color
Wavelength (nm)
Forward Voltage (Vf)
Semiconductor Material
Digital Multimeter — Interactive Simulator
MODE: OFF---
Probe Connections
Red Probe Jack
COM
V / Ω / Hz
mA / A
Measurement Mode (Dial)
OFF
DC Voltage
AC Voltage
Resistance Ω
DC Current
Diode Test ►|
Continuity ))
Frequency Hz
Capacitance
💡 Select a dial mode, connect red probe to V/Ω jack, then choose what to measure.
Knowledge — Digital Multimeter
What is a Multimeter?
A multi-function electronic test instrument combining voltmeter, ammeter, and ohmmeter in a single device. Modern digital multimeters (DMM) display readings on an LCD and include auto-ranging for the correct measurement scale.
Terminal Connections
COM: Always connect black probe here (common ground reference)
V/Ω/Hz: Red probe for voltage, resistance, frequency, diode, capacitance
mA/A: Red probe ONLY when measuring current — never for voltage!
How to Measure
Voltage: Connect in PARALLEL across the component being tested
Current: Connect in SERIES — you must break the circuit
Resistance: Measure with component de-energized (power OFF)
⚠ Never measure resistance/continuity on a live (powered) circuit — this will damage the meter!
⚠ Never put red probe in mA/A jack then measure voltage — internal fuse will blow!
Interactive Breadboard — Click holes to place components
Wire (+)
Wire (GND)
Wire (Signal)
Wire (Data)
LED
Resistor
🗑 Erase
How Breadboard Works:
🔴 Red rails (+) — All holes connected horizontally (power line)
🔵 Blue rails (−) — All holes connected horizontally (ground line)
🟢 Rows A–E & F–J — Holes in same row & column are internally connected vertically
📌 Click a hole with a selected tool to place a component or wire
Knowledge — Breadboard
What is a Breadboard?
A solderless prototyping board with spring-clip contacts inside each hole. Component leads are inserted to make electrical contact without soldering — perfect for testing circuits before committing to a PCB design.
Internal Connection Layout
Power rails (top & bottom) run horizontally the full board length
Component rows run vertically — 5 holes per group (A–E or F–J)
The center gap divides rows — IC chips straddle it for dual access
Maximum current per rail: typically 1–3A depending on board quality
Pro Tips
Color-code wires: Red = VCC, Black = GND, others = signals
Keep wires short and close to the board surface for clarity
Place ICs straddling the center gap for full pin access
Add 100nF bypass capacitors near IC power pins to reduce noise
Use continuity mode on multimeter to verify connections
Demo Circuit: Battery (+9V) → 470Ω Resistor → LED Anode → LED Cathode → GND
R = (9V − 2V) / 20mA = 350Ω → nearest E24 value: 470Ω