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// 15 FREE GUIDES · WITH CALCULATORS

Electronics guides & calculators

Plain-English guides with the formula, worked examples and a free calculator built in: your electricity bill, resistor colour codes, LED resistors, Ohm's law, multimeters, batteries and more. Written for total beginners, worldwide.

CircuitsHome energyDigital & ArduinoToolsBatteries & powerComponents
// CIRCUITS

Circuits

5 guides

Circuits · 4 min readAC vs DC: What's the Difference? (And How Chargers Turn AC Into DC)AC vs DC in plain English: what each one is, 50 Hz vs 60 Hz, why homes use AC and phones use DC, and how a diode bridge turns AC into DC.Read the guide →Circuits · 3 min readOhm's Law Explained Simply: V = I × R With Real ExamplesOhm's law in plain English: V = I × R, the triangle trick, power P = V × I, and real examples with LEDs, chargers and heaters. Free calculator.Read the guide →Circuits · 3 min readRC Time Constant Explained: How Fast Does a Capacitor Charge?τ = R × C tells you how fast a capacitor charges: 63 % after 1 τ, over 99 % after 5 τ. Worked examples, the charging curve, uses and a free simulator.Read the guide →Circuits · 3 min readSeries and Parallel Resistors: Formulas, Examples and CalculatorResistors in series add up; in parallel the total gets smaller. Formulas, the two-resistor shortcut, worked examples and a free calculator.Read the guide →Circuits · 3 min readVoltage Divider Formula and Calculator (5 V to 3.3 V Example)Voltage divider formula Vout = Vin × R2 ÷ (R1 + R2), resistor pairs for 5 V to 3.3 V, sensors like LDRs, and a free calculator.Read the guide →
// HOME ENERGY

Home energy

2 guides

Home energy · 5 min readAppliance Power Consumption Chart: How Many Watts Does an AC, Fridge or TV Use?How many watts does an AC, fridge, TV, fan, laptop or water heater use? A clear wattage chart with real kWh per month for 30+ home appliances.Read the guide →Home energy · 5 min readHow to Calculate Your Electricity Bill (kWh per Appliance) + Free CalculatorCalculate your electricity bill from watts, hours and price per kWh. Simple formula, worked examples for AC, fridge, heater and TV, plus a free calculator.Read the guide →
// DIGITAL & ARDUINO

Digital & Arduino

3 guides

Digital & Arduino · 3 min readBinary to Hex (and Decimal) Conversion Made Easy: 8-Bit GuideConvert binary to decimal and hex in seconds: place values, the nibble trick, a 0–F table and examples like 0x20 = 32. Free bit flipper.Read the guide →Digital & Arduino · 3 min readLogic Gates Explained: AND, OR, NOT, NAND, NOR, XOR (Truth Tables)The 7 basic logic gates — AND, OR, NOT, NAND, NOR, XOR, XNOR — with truth tables, everyday examples and a free logic gate simulator.Read the guide →Digital & Arduino · 3 min readPWM Explained: How analogWrite Dims an LED on Arduino (Duty Cycle)What PWM is, how duty cycle sets the average voltage, and how Arduino analogWrite (0–255) dims LEDs and controls motors. PWM pins, frequency, simulator.Read the guide →
// TOOLS

Tools

1 guide

Tools · 4 min readHow to Use a Multimeter: A Beginner's Guide (Volts, Ohms, Continuity, Amps)Learn to use a multimeter step by step: every dial symbol, which hole each probe goes in, and how to measure volts, ohms, continuity and amps safely.Read the guide →
// BATTERIES & POWER

Batteries & power

2 guides

Batteries & power · 4 min readInverter Battery Backup Time: How to Calculate It (Formula + Free Calculator)How long will your inverter battery last? Backup time formula (V × Ah × efficiency ÷ load), 150 Ah and 200 Ah examples, and a free calculator.Read the guide →Batteries & power · 4 min readmAh to Wh: How Many Charges Will a Power Bank Really Give? (Calculator)Convert mAh to Wh and see how many times a 10,000 or 20,000 mAh power bank really charges your phone. Formula, losses, airline rule, free calculator.Read the guide →
// COMPONENTS

Components

2 guides

Components · 4 min readWhat Resistor Do I Need for an LED? (5 V, 12 V, 3.3 V, 9 V) + CalculatorFind the right LED resistor with R = (Vs − Vf) ÷ I. Ready values for 3.3 V, 5 V, 9 V and 12 V, resistor wattage, and a free LED resistor calculator.Read the guide →Components · 3 min readResistor Color Code Chart: How to Read 4-Band and 5-Band ResistorsRead any resistor in seconds: color code chart for 4-band and 5-band resistors, digits, multiplier, tolerance, worked examples and a free decoder.Read the guide →