Ohmstead

Ohmstead is a complete electronics reference and calculator bench that runs entirely on your device. It gathers the lookups and math a hardware engineer, repair tech, maker, or student reaches for dozens of times a day into one clean, ad-free workspace that works on a plane, in a lab with no signal, or in the field. Everything is bundled on device. There is no account, no login, and nothing to fetch from a server. WHAT'S INSIDE Calculators (44 tools) • Ohm's law and power, voltage and current dividers, series/parallel networks • LED series resistor, zener regulator, and battery runtime • Capacitive and inductive reactance, LC resonance, series-RLC Q and bandwidth • RC and RL filter cutoffs, Sallen-Key corner, RMS and peak conversions • 555 astable and monostable, RC time constants • Op-amp gain (inverting and non-inverting), gain-bandwidth, slew-rate limit • Wavelength and antenna lengths, coax and microstrip impedance, skin depth, VSWR • PCB trace width (IPC-2221), wire voltage drop • Buck/boost duty, transformer turns, capacitor and inductor energy, junction temperature • ADC resolution, PWM average, frequency and period • Wheatstone bridge, NTC thermistor, air-core inductor Decoders • Interactive 4, 5, and 6-band resistor color code with a live resistor preview • SMD code lookup: 3-digit, 4-digit, and EIA-96 Component & connector library • Hundreds of real parts with pinouts and specs: 74xx and 4000 logic, op-amps and comparators, voltage regulators, BJTs and MOSFETs, diodes, zeners, LEDs, and popular microcontrollers • Connector pinouts: USB-A/C, HDMI, VGA, DB9, RJ45, SATA, microSD, SWD/JTAG, the Raspberry Pi 40-pin header, ATX power, and more • Part cross-reference for common substitutes Standards tables • E6 through E192 preferred values, each with full color bands, SMD codes, nearest-neighbor cross-references, and power ratings • Capacitor 3-digit code decoder • AWG wire table with diameter, resistance, and ampacity • IPC-2221 PCB trace width • Reactance/impedance chart for standard capacitor and inductor values across frequency • SI prefixes, physical constants, a decibel ladder, logic-family levels, dielectric types, and battery chemistries Bench sheets • Save any calculation as a named bench sheet and pin your favorite calculators to the home screen Built for engineers who want their reference material to be accurate, fast, and always available.