Reference sheets

Electronics reference sheets: codes, values, tables and rules of thumb for the bench.

Parts & markings

• Capacitor codes104 = 100 nF — decode the three-digit marking and its tolerance letter
• Capacitor ESR & rippleWhat ESR costs you, family by family
• Capacitor typesX7R vs C0G vs electrolytic — which dielectric for which job
• Common diodes1N4001, 1N4148, Schottky and zeners with their real limits
• Crystal load capacitorsSize C1 and C2 from the crystal's CL, and why it matters
• E12/E24 valuesThe resistor values that actually exist, and their tolerances
• LED forward voltageVf per colour, so the series resistor comes out right
• MOSFET comparisonWhich jellybean part actually switches fully at 3.3V or 5V
• Op-amp comparisonLM358, TL072, MCP6002 and co: supply, offset, speed
• Relay contactsSPDT, NO / NC, coil voltages and the flyback diode
• SMD packagesChip sizes drawn to scale, from 0201 to 2512
• Transistor hFEGain and ratings for the jellybean BJTs, lead order included

Formulas, units & symbols

• AbbreviationsSMD, BOM, ESR, PTH: the jargon on datasheets and fab files
• dBm powerDecibel-milliwatt to watts, and what each level means
• Ohm's law wheelTwelve formulas linking V, I, R and P
• ResistivityHow well common materials conduct
• Schematic symbolsEvery symbol the app draws, with its designator letter
• SI prefixesPico to giga, with the factors written out

Wiring & connectors

• AWG wire gaugeGauge to mm² and the current a wire can really carry
• Connector familiesJST XH / PH / SH, Molex, Dupont: pitch, current, where found
• Connector gender & keyingMale or female, and what stops it going in backwards
• Connector pitchesDrawn to scale — the 2.54 vs 2.5 mm trap in one look
• Heat shrink sizesThe tube for each wire gauge, with shrink ratios
• PCB design rulesTrace width and current, spacing, rings, drills, copper weight
• PCB stackup2, 4 or 6 layers, and what a ground plane buys you
• Screws & standoffsM2 / M2.5 / M3 sizes and the mounting holes on common boards
• Via currentHow much current a via carries, and when to use several
• Wiring coloursThe colour conventions for DC, mains and signal wiring

Power & protection

• Battery chargingCC-CV per chemistry, and the mistake that starts fires
• Battery typesChemistries, cell voltages and what each one is good at
• Decoupling capacitorsWhy every IC needs one, which values, and where to put them
• Fuses & protectionFast vs slow blow, polyfuses, TVS and reverse-polarity guards
• Motor typesDC, stepper, servo, brushless: control and drivers
• Thermal managementTj, θJA, and when a part needs copper or a heatsink
• USB powerWhat each port really delivers, and why USB-C needs its resistors
• Voltage regulators7805, LM317, LDOs and buck modules side by side

Digital, boards & sensors

• Dev-board comparisonEvery board in the Pinouts tab, spec for spec
• Display typesLCD, OLED, TFT, e-paper: speed, power, sunlight
• I2C addressesWhat that hex address from a bus scan actually is
• Logic levelsVIH / VIL per family — what damages what
• Memory & storageEEPROM, flash, FRAM, SD: endurance, speed, retention
• Radio bandsISM bands, power limits and what lives on each
• Sensor pickerWhich sensor for temperature, distance, light or current
• Serial protocolsUART, I2C, SPI, CAN and friends: wires, speed, reach
• UART baud & framingBit times per baud rate, and what 8N1 really sends
• Wireless comparisonBLE, WiFi, LoRa, Zigbee: range, rate, power and licence

Workshop & measuring

• ESD & handlingWhat really kills parts, and what the bags actually do
• Flux typesRosin, no-clean, water-soluble, and which must be washed off
• Multimeter guideEvery dial position, burden voltage, and that fuse
• Oscilloscope basics1x vs 10x, compensation, triggering, aliasing
• Solder joint qualityRead a joint by its shape: cold, dry, bridged, tombstoned
• Soldering & reworkAlloys, iron temperatures, tip choice and flux