Ohmβs Law Cheat Sheet
Quick-reference formulas for voltage, current, resistance, and power.
Utilities Bunker Resource Hub
Resources Library
Fast, structured technical references for electronics, computing, AI, engineering, science, math, security, and general utility work.
About the Resources Library
This section is built for quick-reference use: open a topic, get the essentials, and move on. No fluff, no maze, no slow-loading nonsense.
Current library count: 197 resources across 10 main sections.
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Electronics & Power
Resistor Color Codes
Band decoding, tolerance colors, and common resistor markings.
Resistor Series & Tolerances
E-series overview from E6 through E192 and typical tolerance classes.
LED Resistor Table
Forward voltage, current targets, and resistor sizing guidance by LED color.
AWG Current Capacity
Wire gauge, ampacity, resistance, and sizing reference.
Wire Gauge Table
AWG diameter, cross-sectional area, and equivalent sizing data.
Power Formulas (AC/DC)
Core power formulas for DC, single-phase AC, and three-phase systems.
Three-Phase Basics
Relationships between line voltage, phase voltage, current, and power.
Capacitor Types & Uses
Ceramic, film, electrolytic, tantalum, and practical use cases.
RC Charge Time
Charge and discharge timing basics for RC circuits and time constants.
Inductor Core Materials
Ferrite, powdered iron, and common magnetic core tradeoffs.
Electronics Packages
Common SMD and through-hole package reference guide.
Transistor Pinouts
Typical BJT and MOSFET package pin arrangements.
MOSFET vs IGBT
Switching behavior, losses, speed, and application differences.
Power Supply Standards
ATX, SFX, barrel connectors, USB PD, and general PSU references.
PSU Efficiency & 80 PLUS
Efficiency curves, load behavior, and certification reference.
PSU Noise Filtering
Ripple reduction, LC filtering, and power cleanliness basics.
Signal-to-Noise Ratio
dB conversions, interpretation, and common examples.
RF Cable Attenuation
Cable loss versus length and frequency reference.
RF Connectors
SMA, BNC, N-type, impedance notes, and connector selection.
Antenna Types
Dipole, Yagi, patch, monopole, and directional antenna basics.
Transformer Turns Ratio
Voltage, current, and winding ratio quick reference.
Buck vs Boost
Step-down versus step-up regulator concepts and tradeoffs.
Switching Regulator Efficiency
Efficiency behavior across load and topology choices.
Thermal Resistance (ΞΈJA / ΞΈJC)
Thermal path concepts for components, packages, and heatsinks.
Thermal Derating
Component ratings and safe operating behavior versus temperature.
Charging Voltage Table
Common battery chemistry voltage targets and charge ceilings.
Battery Self-Discharge
Discharge rate reference by chemistry and storage condition.
Battery Charge Algorithms
CC/CV, balancing, trickle, and common charging methods.
Battery Discharge Curves
Runtime behavior and discharge profile reference by chemistry.
Relay & Switch Types
SPST, SPDT, DPDT, contact forms, and use-case basics.
Fuse Types & Ratings
Blade, glass, ceramic, fast-blow, and slow-blow reference.
Power Factor Reference
Power factor basics, correction, and system behavior.
Clock Frequency Tolerances
Crystal ppm, drift, stability, and oscillator reference notes.
Signal Integrity Basics
Reflections, ringing, impedance, and termination fundamentals.
PCB Design Rules
General board layout guidelines, clearances, and manufacturability basics.
PCB Trace Width Guide
Current, copper weight, and trace width relationship reference.
PCB Layer Stackups
Practical 2, 4, 6, and 8-layer board stack examples.
PCB Materials
FR-4, Rogers, dielectric constant, Tg, and material properties.
Eddy Current Loss
Frequency-related magnetic losses and core behavior notes.
Power Loss Guide
Conduction, switching, thermal, and efficiency loss concepts.
Embedded Protocols
SPI, I2C, UART, CAN, and RS-485 quick reference.
Motor Driver ICs
Common motor control IC families and popular module choices.
Servo vs Stepper
Control style, torque behavior, and application comparison.
Computing & Networking
USB Versions & Speeds
USB generations, connectors, and transfer speed summary.
Storage Interfaces
SATA, NVMe, PCIe lanes, and storage interconnect comparison.
Memory Hierarchy
Registers, cache, RAM, and storage role overview.
CPU vs GPU
Parallelism, throughput, and processing model differences.
Filesystem Types
NTFS, exFAT, ext4, APFS, Btrfs, and common tradeoffs.
Ports & Interfaces
USB, DisplayPort, HDMI, serial, and internal interface reference.
Floating-Point Formats
IEEE-754 binary floating-point structure and data formats.
Floating-Point Errors
Rounding, NaN, infinity, and precision pitfalls.
File Size Conversions
Bytes through tebibytes with decimal and binary comparisons.
Network Cable Standards
Cat5e through Cat8 bandwidth and wiring reference.
Wi-Fi Bands & Channels
2.4 GHz, 5 GHz, and channel overlap basics.
DNS Record Types
A, AAAA, CNAME, MX, TXT, NS, and related records.
HTTP Methods
GET, POST, PUT, PATCH, DELETE, and request behavior.
SSL/TLS Versions
Protocol history, version comparison, and security basics.
Web Performance Metrics
Core Web Vitals and page speed measurement basics.
Linux Shell Commands
Practical command-line admin and troubleshooting reference.
SQL Datatypes
Common MySQL, PostgreSQL, and SQLite type reference.
Editor Shortcuts
Common IDE and editor productivity shortcuts.
Language Syntax
Quick syntax comparisons for common programming languages.
Internet Protocol History
IPv4, IPv6, HTTP evolution, and major web milestones.
USB Power Delivery
Profiles, power negotiation, and cable compatibility notes.
Optical Fiber Types
Single-mode, multimode, wavelength windows, and loss basics.
Computer Architecture
ALU, buses, memory, and control structure overview.
Connector Pinouts
USB, HDMI, RJ45, ATX, and general connector reference.
Bluetooth Versions
Version history, rate improvements, and range comparison.
Wireless Protocols
LoRa, Zigbee, NFC, UWB, and wireless tradeoff overview.
File Extensions
Common file types, categories, and software associations.
MIME Types
Content types used for uploads, downloads, and HTTP headers.
Cache & Memory
Latency, bandwidth, and memory hierarchy comparison.
AI & Data Science
AI Model Types
CNN, RNN, LSTM, transformer, and model family basics.
AI Evaluation Metrics
Precision, recall, F1, BLEU, ROUGE, and related measures.
Token Limits & Costs
Context windows, token sizing, and usage planning notes.
Embedding Models
Dimensionality, use cases, and embedding model reference.
Model Quantization
INT8, FP16, pruning, distillation, and deployment tradeoffs.
Activation Functions
ReLU, GELU, sigmoid, tanh, and practical behavior.
Loss Functions
MSE, MAE, cross-entropy, hinge, and optimization basics.
Gradient Descent
Learning rate, convergence, and optimization intuition.
Dataset Formats
JSONL, CSV, COCO, VOC, TFRecord, and dataset packaging.
Hash Algorithms
SHA-2, SHA-3, BLAKE3, speed, and integrity use cases.
Embedding Use Cases
Search, clustering, semantic similarity, and RAG use cases.
PID Tuning (Control)
PID fundamentals and common manual tuning approaches.
System Design Patterns
REST, event-driven systems, queues, MVC, and service patterns.
Data Visualization Types
Which chart type to use for different data situations.
Statistical Tests
t-tests, chi-square, ANOVA, and significance basics.
Correlation Guide
Correlation strength, r-values, and common interpretation pitfalls.
Error Propagation
How uncertainty combines across measured calculations.
JSON vs XML
Structure, readability, overhead, and use-case comparison.
JSON Schema Examples
Schema validation examples and structure patterns.
File Hash Algorithms
MD5, SHA-256, bcrypt, and file integrity reference.
Password Strength
Entropy, length, and crack-resistance concepts.
Data Transfer Time
Estimated transfer times by bitrate and payload size.
Model Parameter Sizes
Memory usage, parameter count, and rough model sizing.
Embedding Evaluation
Similarity scoring and embedding quality comparison ideas.
Math & Physics
Physics Constants
Fundamental constants used across science and engineering.
EM Spectrum
Frequency, wavelength, and energy across the spectrum.
Trig Cheat Sheet
Unit circle, identities, and common trigonometric relationships.
Geometry Formulas
Area, perimeter, surface area, and volume formulas.
Triangle Identities
Law of sines, law of cosines, and triangle relationships.
Matrix Operations
Addition, multiplication, determinants, and inverses.
Matrix Decompositions
SVD, LU, QR, and Cholesky overview.
Dimensionless Numbers
Reynolds, Mach, Prandtl, Froude, and engineering significance.
Fourier Transform
DFT, FFT, and transform intuition for signals.
Speed of Light Conversions
Light-seconds, AU, light-years, and parsec comparisons.
Earth Constants
Radius, mass, gravity, density, and major planetary constants.
Planetary Data
Comparative data for planets, orbits, and basic properties.
Planetary Gravity
Surface gravity and escape velocity by planetary body.
Gas Laws
Boyle, Charles, Avogadro, and ideal gas basics.
Water Properties
Density, viscosity, heat capacity, and temperature behavior.
Thermal Conductivity
Reference conductivity values for common materials.
Thermal Expansion
Expansion coefficients for metals, plastics, and other materials.
Humidity & Dew Point
Basic psychrometric reference and moisture relationships.
Escape Velocity
Equation reference and worked spaceflight examples.
Moment of Inertia
Common beam and body formulas for mechanical analysis.
Mechanical Conversions
Torque, pressure, force, energy, and engineering unit conversions.
Density / Mass / Volume
Quick reference relationships and worked examples.
Statistical Distributions
Normal, binomial, Poisson, and other common distributions.
Thermodynamics Laws
First through third law overview and core thermal concepts.
Fluid Dynamics
Laminar versus turbulent flow and major fluid concepts.
Mechanical & Materials
Material Properties
Density, tensile strength, thermal behavior, and material basics.
Thread Sizes
Metric and imperial threads, pitches, and size reference.
Bolt Torque Specs
General torque ranges by fastener size and grade.
Bearing Types
Ball, roller, thrust, and load type comparisons.
Spring Constants
Helical, torsion, leaf, and spring rate fundamentals.
Mechanical Leverage
Mechanical advantage formulas and lever class overview.
Tolerances (ISO 2768)
General machining tolerance reference for common parts.
Optical Lens Formulas
Thin-lens relationships and optical magnification equations.
Fastener Materials
Alloy, stainless, titanium, and common fastener material choices.
IP Protection Codes
IP ratings from dust and splash resistance through washdown.
Safety Symbols
Common electrical warning, grounding, and protection symbols.
Connector Pinouts
General quick-reference connector and power pinout notes.
Optics & Wavelengths
Visible spectrum, wavelength, color, and energy reference.
Thermal Interfaces
Thermal pads, paste, and interface material basics.
Power Derating with Temp
How temperature affects safe power and component ratings.
Magnetic Units
Tesla, gauss, oersted, and magnetic unit conversions.
Coil Inductance Guide
Solenoid and toroid inductance concepts and formulas.
AC Waveform Distortion
Harmonics, waveform quality, and THD fundamentals.
Antenna Patterns
Gain, beamwidth, lobes, and radiation shape basics.
Power Factor (Mech)
Practical equipment impact of low and corrected power factor.
Environment & Chemistry
Periodic Table
Element symbols, atomic number, and core chemistry reference.
Element Properties
Melting point, boiling point, density, and element behavior.
Combustion Energy
Fuel energy density reference in common engineering units.
Atmosphere Layers
Troposphere through exosphere with altitude overview.
Solar Irradiance
Solar energy levels by condition, angle, and environment.
Water Properties
Density, viscosity, and thermal behavior of water.
Humidity & Dew Point
Basic air moisture and dew point reference.
Expansion Coefficients
Thermal expansion values for common materials.
Battery Charging
Voltage targets and chemistry charging reference.
Environmental Standards
RoHS, WEEE, ISO 14000, and environmental compliance basics.
Gas Laws
Pressure, volume, and temperature gas-law relationships.
Water Density vs Temperature
Density lookup behavior across temperature ranges.
Planetary Atmospheres
Atmospheric composition across major planetary bodies.
Fuel Properties
Density, energy content, and key fuel comparison notes.
Earth Constants
Earth system constants relevant to chemistry and environment.
Audio & Optics
Sound Pressure Levels
dB SPL examples and loudness reference points.
Audio Frequency Bands
Sub-bass through treble and common band breakdowns.
Audio Sampling Theory
Nyquist, sample rate, bit depth, and digital audio basics.
Microphone Types
Dynamic, condenser, ribbon, and polar pattern reference.
Color Temperature
Kelvin scale examples for light source appearance.
Optical Lens Formulas
Thin-lens equation and focal behavior reference.
Camera Sensor Sizes
APS-C, full frame, Micro Four Thirds, and crop factor notes.
Exposure Triangle
ISO, aperture, shutter speed, and image exposure basics.
Light Wavelengths
Color, wavelength, and visible spectrum quick reference.
Optical Fiber Types
Fiber classes, windows, and basic optics transport overview.
Aerospace & Robotics
Orbital Mechanics Basics
Keplerβs laws, orbital motion, and transfer basics.
Escape Velocity
Planetary escape velocity formulas and examples.
Planetary Gravity
Gravity comparison across planets and major bodies.
GPS Accuracy & Errors
WAAS, DGPS, drift, and multipath error basics.
Robotics Sensors
LIDAR, encoders, IMUs, ultrasonic, and sensor roles.
Firmware Updates
Bootloader, DFU, OTA, and firmware delivery methods.
Model Quantization (Edge)
Low-precision model deployment ideas for edge devices.
Clock Tolerances
Timing drift, oscillator precision, and synchronization concerns.
Sensor Calibration
Offset, gain trim, and basic sensor calibration practices.
Motor Types
DC, AC, stepper, brushless, and control comparison notes.
Security & DevOps
Security Headers
CSP, HSTS, X-Frame-Options, and hardening basics.
Encryption Algorithms
AES, RSA, ECC, ChaCha20, and encryption reference.
Modes of Operation
ECB, CBC, CTR, GCM, and authenticated encryption basics.
HTTP Status Codes
Response code meanings and practical web examples.
Versioning Conventions
Semantic versioning, release tags, and version strategy basics.
DevOps Pipeline
Build, test, deploy, release, and CI/CD flow overview.
Performance & Security
Performance-security balance and implementation tradeoffs.
Cybersecurity Basics
CIA triad, threats, attack surface, and protection concepts.
IPv4/IPv6 & CIDR
Private ranges, masks, subnet basics, and addressing overview.
DNS Records (Ops)
Operational DNS record quick reference for infrastructure.
General Reference
Color Codes
HEX, RGB, HSL, and color format reference.
SI Units & Prefixes
Metric base units and power-of-ten prefixes.
Engineering & Binary Prefixes
k, M, G versus Ki, Mi, Gi notation reference.
Binary / Decimal / Hex
Quick conversion relationships and number system basics.
Number Systems
Binary, octal, decimal, hexadecimal, and representation basics.
HTML & CSS Cheat Sheet
Core tags, selectors, and useful shorthand reference.
Regex Cheat Sheet
Pattern syntax, anchors, groups, classes, and examples.
Markdown Syntax
Common Markdown formatting patterns and usage guide.
Unit Conversion Table
Common engineering unit relationships across categories.
Formulas Index
Jump-off point for formulas, tools, and related references.