#electronics

Resistive voltage-divider circuit design as an API, computed locally and deterministically. The divide endpoint takes an input voltage and two resistors and returns the output voltage Vout = Vin·R2/(R1+R2), the current I = Vin/(R1+R2) that flows through the chain, and the power dissipated in each resistor and in total — a 12 V source with R1 = 1 kΩ and R2 = 2 kΩ gives 8 V at 4 mA. The loaded endpoint adds a load resistor across R2, computes the parallel combination R2′ = R2·RL/(R2+RL) and the loaded output Vout = Vin·R2′/(R1+R2′), and reports the droop in volts and percent against the unloaded value, the classic mistake when a divider feeds a real load. The resistor endpoint sizes the missing resistor for a target output — R2 = R1·Vout/(Vin−Vout) or R1 = R2·(Vin−Vout)/Vout — so you can pick parts for a reference or sensor-bias point. All quantities are volts, ohms, amps and watts. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, embedded, hardware, sensor-interfacing and EE-education app developers, reference-voltage and bias-network tools, and maker software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the resistive divider; for a single Ohm’s-law relationship use an Ohm’s-law API and for RC/RL filters an RC-filter API.

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First-order RC and RL passive-filter design as an API, computed locally and deterministically. The lowpass and highpass endpoints take a resistor and capacitor (RC) or a resistor and inductor (RL) and return the −3 dB cutoff frequency (fc = 1/(2πRC) for RC, R/(2πL) for RL), the time constant (τ = RC or L/R) and the angular cutoff; pass a frequency as well and they add the magnitude response as a linear gain and in decibels and the phase shift in degrees — a 1 kΩ / 1 µF low-pass has fc ≈ 159.15 Hz, and right at the cutoff the gain is −3.01 dB with −45° phase for a low-pass or +45° for a high-pass. The component endpoint solves the missing one of fc, R and C from the other two (fc = 1/(2πRC)), so you can size a resistor or capacitor for a target cutoff. All quantities are SI: ohms, farads, henries and hertz. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, audio, embedded, signal-processing and EE-education app developers, filter-design and circuit-sizing tools, and maker software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is first-order single-pole filter design; for full RLC impedance and resonance use an impedance API and for stored capacitor energy a capacitor API.

api.oanor.com/rcfilter-api

Chebyshev Type I filter-design maths as an API, computed locally and deterministically. The order endpoint computes the minimum filter order to meet a specification, n = ⌈acosh(√((10^(As/10)−1)/(10^(Ap/10)−1))) / acosh(fs/fp)⌉, from the passband edge frequency and its ripple and the stopband edge and its required attenuation — a Chebyshev filter usually needs a lower order than a Butterworth for the same specification, trading a flat passband for equiripple. The response endpoint computes the equiripple magnitude response, |H| = 1/√(1 + ε²·Tₙ²(f/fc)) with the ripple factor ε = √(10^(Ap/10) − 1) and the Chebyshev polynomial Tₙ, in linear and decibel form — in the passband the magnitude ripples between 0 and −Ap dB and reaches exactly −Ap dB at the cutoff, then rolls off faster than a Butterworth. The ripple endpoint converts between the passband ripple in decibels and the ripple factor ε, with the passband maximum and minimum. Frequencies are in hertz, ripple and attenuation in decibels and the order a positive integer. Everything is computed locally and deterministically, so it is instant and private. Ideal for DSP, audio, RF, communications and instrumentation app developers, filter-design and selectivity tools, and signal-processing education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Chebyshev Type I filter; for the maximally-flat Butterworth use a Butterworth API.

api.oanor.com/chebyshev-api

Butterworth-filter design maths as an API, computed locally and deterministically. The order endpoint computes the minimum filter order needed to meet a specification — from the passband edge frequency and its allowed ripple and the stopband edge frequency and its required attenuation it returns the exact and rounded-up order, n = ⌈log10((10^(As/10)−1)/(10^(Ap/10)−1)) / (2·log10(fs/fp))⌉, where each extra order adds 20 dB per decade of roll-off. The response endpoint computes the maximally-flat magnitude response of an n-th order Butterworth filter at a frequency, |H| = 1/√(1 + (f/fc)^(2n)), in linear and decibel form with the attenuation and the asymptotic roll-off — the response is exactly −3.01 dB at the cutoff for any order. The poles endpoint gives the s-plane pole locations, equally spaced on a circle of radius ωc in the left half-plane at angles π·(2k+n−1)/(2n), all stable. Frequencies are in hertz (or any consistent unit), ripple and attenuation in decibels and the order a positive integer. Everything is computed locally and deterministically, so it is instant and private. Ideal for DSP, audio, RF, instrumentation and embedded app developers, anti-aliasing and filter-design tools, and signal-processing education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Butterworth filter; for a single-pole RC cutoff and resonance use a resonance API and for AC impedance an impedance API.

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Zener-diode voltage-regulator electronics maths as an API, computed locally and deterministically. The series-resistor endpoint sizes the series (dropping) resistor for a shunt Zener regulator, Rs = (Vin − Vz)/(Iz + Il), from the input voltage, the Zener voltage, the load current and the desired Zener (knee) current, and gives the power the resistor and the Zener must dissipate — the core design step so the diode stays in regulation at maximum load. The regulator endpoint analyses an existing regulator: from the input voltage, the Zener voltage, the series resistor and the load (as a current or a resistance) it computes the total current, the Zener current Iz = (Vin − Vz)/Rs − Il, the load current, the output voltage and whether the regulator is still regulating (Iz > 0) or has dropped out under heavy load. The power endpoint computes the Zener power dissipation P = Vz·Iz and the maximum safe current Iz_max = Pz_max/Vz from the diode's power rating. Voltages are in volts, currents in amperes, resistances in ohms and power in watts. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, power-supply, hobbyist and embedded app developers, regulator-design and reference-voltage tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Zener shunt regulator; for BJT biasing use a transistor API and for an LED series resistor an LED-resistor API.

api.oanor.com/zener-api

Bipolar-junction-transistor (BJT) circuit maths as an API, computed locally and deterministically. The currents endpoint relates the three terminal currents through the DC current gain β (hFE): the collector current Ic = β·Ib, the emitter current Ie = (β+1)·Ib and the common-base gain α = β/(β+1) ≈ 1, from β and any one current. The bias endpoint analyses the operating point of the classic voltage-divider bias network — from the supply voltage, the two divider resistors, the collector and emitter resistors, β and the base-emitter drop it computes the Thévenin equivalent (Vth = Vcc·R2/(R1+R2), Rth = R1‖R2), the base current Ib = (Vth − Vbe)/(Rth + (β+1)·Re), the collector and emitter currents, the collector-emitter voltage Vce and the node voltages, and classifies the operating region as cutoff, active or saturation. The power endpoint computes the transistor's power dissipation, Pd ≈ Vce·Ic (plus Vbe·Ib), to check it against the rated maximum. Currents are in amperes, resistances in ohms and voltages in volts, with Vbe defaulting to 0.7 V for silicon. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, amplifier-design, embedded and hobbyist app developers, biasing and operating-point tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is BJT biasing; for op-amp circuits use an op-amp API and for an LED series resistor an LED-resistor API.

api.oanor.com/transistor-api

Inductor-design electromagnetics as an API, computed locally and deterministically. The solenoid endpoint computes the inductance of a straight coil with the long-solenoid formula L = μ₀·μr·N²·A/l, from the number of turns, the coil length, the cross-sectional area (or diameter) and the relative permeability of the core — a ferromagnetic core multiplies the inductance. The toroid endpoint computes the inductance of a doughnut-shaped coil of rectangular cross-section, L = μ₀·μr·N²·h·ln(b/a)/(2π), from the turns, the axial height and the inner and outer radii; the toroidal shape confines the magnetic flux so there is little stray field. The energy endpoint computes the magnetic energy stored in an inductor, E = ½·L·I², and the flux linkage Φ = L·I, from the inductance and current — the energy released when the current is interrupted causes the inductive kick. Lengths are in metres, area in square metres, inductance in henries (millihenries and microhenries also returned) and current in amps, with μ₀ = 4π×10⁻⁷ H/m. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, RF, power-supply, filter and motor-design app developers, coil-winding and inductor-sizing tools, and electromagnetics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is inductance from geometry; for the resonant frequency and reactance use a resonance API and for full AC impedance an impedance API.

api.oanor.com/inductance-api

AC complex-impedance maths as an API, computed locally and deterministically. The series endpoint computes the impedance of a series R-L-C circuit at a given frequency — the inductive reactance X_L = 2πf·L, the capacitive reactance X_C = 1/(2πf·C), the complex impedance Z = R + j(X_L − X_C), its magnitude |Z| = √(R²+X²) and phase angle φ = atan(X/R) — and classifies the circuit as inductive (current lags), capacitive (current leads) or resistive. The parallel endpoint computes a parallel R-L-C impedance through its admittance Y = 1/R + j(ωC − 1/ωL) and Z = 1/Y, with magnitude and phase. The ac-ohm endpoint applies Ohm's law for AC, I = V / |Z|, to give the RMS current and apparent power from an RMS voltage and an impedance specified either as resistance and reactance or as a magnitude, and the real power when the phase is known. Resistance and reactance are in ohms, inductance in henries, capacitance in farads, frequency in hertz and voltage RMS in volts; phase is in degrees. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, audio, RF-filter, power-supply and motor-control app developers, AC-circuit and phasor tools, and electrical-engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is AC complex impedance; for the resonant frequency and reactance alone use a resonance API and for power-factor correction a power-factor API.

api.oanor.com/impedance-api

NTC-thermistor sensor maths as an API, computed locally and deterministically. The steinhart-hart endpoint converts between resistance and temperature using the Steinhart-Hart equation, 1/T = A + B·ln R + C·(ln R)³ — the most accurate NTC model — in both directions, solving the resistance at a given temperature with Cardano's cubic formula. The beta endpoint uses the simpler two-point Beta model, 1/T = 1/T0 + (1/β)·ln(R/R0) and R = R0·exp(β·(1/T − 1/T0)), to convert resistance to temperature or back from a reference resistance R0 at T0 (default 25 °C) and the beta coefficient. The divider endpoint recovers the thermistor's resistance from a voltage-divider reading — low-side R = Rs·Vout/(Vsupply − Vout) or high-side — so an ADC voltage can be turned into a resistance and then a temperature. Resistance is in ohms, temperature in °C (kelvin also returned), voltages in volts and beta in kelvin. Everything is computed locally and deterministically, so it is instant and private. Ideal for embedded, IoT, HVAC-control, 3D-printer and battery-management app developers, temperature-sensing and calibration tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is NTC thermistor conversion; for a generic resistive divider use an LED-resistor or voltage-drop API and for thermal expansion a thermal-expansion API.

api.oanor.com/thermistor-api

Capacitor maths as an API, computed locally and deterministically. The energy endpoint computes the stored energy and charge of a capacitor from any two of the capacitance, the voltage and the charge — E = ½CV² = ½QV and Q = CV — in joules, millijoules and coulombs. The charging endpoint models the RC charging and discharging transient: the time constant τ = RC, the voltage at a given time, V(t) = Vs(1 − e^(−t/RC)) when charging or V(t) = V₀·e^(−t/RC) when discharging, and the percent charged, or — given a target voltage — the time to reach it; a capacitor reaches about 63 % of the way in one time constant and over 99 % in five. The combination endpoint computes the total capacitance of capacitors in series (1/C = Σ1/Cᵢ) or parallel (C = ΣCᵢ). Capacitance accepts farads or the handy µF/nF/pF units. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, maker, embedded and circuit-design app developers, power-supply and timing tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is capacitor maths; for AC reactance and resonance use a resonance API and for LED resistor sizing an LED-resistor API.

api.oanor.com/capacitor-api

Printed-circuit-board design maths as an API, computed locally and deterministically. The trace-width endpoint applies the IPC-2221 standard to find the minimum copper trace width for a current and an allowable temperature rise, A = (I/(k·ΔT^0.44))^(1/0.725) with k = 0.048 for outer layers and 0.024 for inner, returning the cross-section and the width in mils and millimetres for a given copper weight. The trace-resistance endpoint computes a trace's resistance from its width, length and copper thickness, R = ρ·L/(W·t), with the copper temperature coefficient, and — given a current — the voltage drop and power dissipation. The microstrip endpoint computes the characteristic impedance of a microstrip line by the Hammerstad model from the trace width, the dielectric height and the dielectric constant (about 4.5 for FR4), with the effective permittivity and propagation delay for controlled-impedance routing. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, hardware, embedded and PCB-design app developers, board-layout and signal-integrity tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is PCB design; for resistor colour codes use a resistor API and for general Ohm's-law maths an Ohm's-law API.

api.oanor.com/pcb-api

ADC/DAC data-converter maths as an API, computed locally and deterministically. The resolution endpoint turns a bit depth into the number of quantization levels (2^N), the LSB step for a given reference voltage (in V, mV and µV), the full-scale range, the ideal signal-to-noise ratio (6.02·N + 1.76 dB) and dynamic range, and — given an input voltage — the digital output code. The sampling endpoint covers Nyquist: the minimum sample rate for a signal bandwidth (2·f_max), the Nyquist frequency for a sample rate (fs/2), whether a signal is adequately sampled, and the alias frequency a tone folds to, |f_in − round(f_in/fs)·fs|. The quantization endpoint gives the maximum quantization error (LSB/2), the rms quantization noise (LSB/√12), the ideal SNR, and the effective number of bits (ENOB = (SNR − 1.76)/6.02) from a measured SNR. Everything is computed locally and deterministically, so it is instant and private. Ideal for embedded, DSP, audio and instrumentation app developers, data-acquisition and converter-selection tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is data-converter & sampling maths; for media bitrate and file size use a bitrate API and for AC reactance and resonance use a resonance API.

api.oanor.com/adc-api

AC reactance and LC/RC tuning maths as an API, computed locally and deterministically. The reactance endpoint computes the capacitive reactance Xc = 1/(2πfC) and the inductive reactance Xl = 2πfL at a given frequency, and — when both a capacitor and an inductor are supplied — the net series reactance X = Xl − Xc, whether the circuit looks inductive, capacitive or resonant, and the impedance magnitude. The resonant endpoint computes the LC resonant frequency f₀ = 1/(2π√(LC)), or, given a target frequency and one component, solves the other component you need to tune to it. The cutoff endpoint computes the RC or RL filter cutoff frequency — fc = 1/(2πRC) for RC, fc = R/(2πL) for RL — and the time constant. Frequencies are in hertz; capacitance, inductance and resistance accept SI base units with handy µF/nF/pF and mH/µH inputs. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, RF, audio-filter and embedded app developers, tuning and filter-design tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is AC reactance & LC/RC tuning; for LED series-resistor sizing use an LED-resistor API and for VSWR and impedance match use a VSWR API.

api.oanor.com/resonance-api

Heatsink and thermal-resistance maths for electronics as an API, computed locally and deterministically. The junction endpoint computes the junction temperature of a component from its power dissipation, the ambient temperature and the thermal-resistance chain, Tj = Ta + P·(Rθjc + Rθcs + Rθsa) — junction-to-case, case-to-sink (the interface material) and sink-to-ambient — and also reports the case and sink temperatures and, given a maximum junction temperature, the headroom. The required endpoint solves the largest heatsink thermal resistance you may use to stay under a junction limit, Rθsa = (Tj_max − Ta)/P − Rθjc − Rθcs, and flags when no heatsink can do it. The power endpoint gives the maximum power a device can dissipate for a given thermal path, P = (Tj_max − Ta)/Rθtotal. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, power-supply and PCB-design app developers, heatsink selection and thermal-budget tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is conduction thermal-resistance; for convective Newton cooling use a cooling API.

api.oanor.com/heatsink-api

LED current-limiting-resistor maths as an API, computed locally and deterministically. The resistor endpoint sizes the series resistor for a single LED, R = (V_supply − V_forward) / I, and returns the resistor power dissipation (I²·R), the LED power, a recommended resistor wattage rating and the nearest E12 standard value (rounded up so the LED current stays at or below the target). The series endpoint sizes the one shared resistor for several LEDs wired in series, where the forward voltages add, R = (V_supply − n·V_f) / I, and flags when the supply is too low for the string. The parallel endpoint gives the per-LED resistor for LEDs in parallel (each needs its own) and the total current the supply must deliver. Currents are entered in milliamps. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, maker, Arduino and hardware app developers, LED and lighting-circuit design tools, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is LED resistor sizing; for general Ohm's law and reactance use an Ohm's-law API and for AWG wire properties use a wire-gauge API.

api.oanor.com/ledresistor-api

AWG (American Wire Gauge) maths as an API, computed locally and deterministically. The awg endpoint returns the physical properties of a gauge — the diameter, 0.127·92^((36−n)/39) mm, the cross-section area, the DC resistance per kilometre and per 1000 ft for copper or aluminium, and the Preece fusing current (the point at which the wire melts, far above any safe operating ampacity). The fromdiameter endpoint goes the other way, giving the nearest AWG for a measured diameter or cross-section area, n = 36 − 39·log₉₂(d/0.127). The resistance endpoint gives the resistance of a wire run from its gauge, length and material, R = ρ·L/A. Gauges 0/0 (1/0), 00 (2/0) and 000 (3/0) are entered as −1, −2 and −3. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics, electrical and maker app developers, wiring and cable-selection tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is wire-gauge geometry and resistance; for cable voltage drop over a circuit use a voltage-drop API.

api.oanor.com/wiregauge-api

555-timer (NE555) astable and monostable design as an API, computed locally and deterministically. The astable endpoint designs the classic oscillator: from the two timing resistors R1 and R2 and the capacitor it returns the output frequency f = 1/(ln2·(R1+2R2)·C), the high and low times (T_high = ln2·(R1+R2)·C, T_low = ln2·R2·C), the period and the duty cycle (R1+R2)/(R1+2R2), or solves the capacitor for a target frequency. The monostable endpoint designs the one-shot timer, T = 1.1·R·C — the pulse width of a single output pulse — and solves for whichever of the resistance, capacitance or pulse width you leave out. The design endpoint works backwards: from a target frequency, a chosen capacitor and a duty cycle it computes the resistor values R1 and R2 you need (a standard 555 needs a duty above 50 %). Capacitors may be entered in farads, microfarads, nanofarads or picofarads. Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics-hobbyist and maker tools, oscillator, blinker, PWM and timing-circuit design, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is 555-timer design; for Ohm's law, reactance and RC time constants use an Ohm's-law API.

api.oanor.com/timer555-api

Operational-amplifier gain and bandwidth maths as an API, computed locally and deterministically. The gain endpoint computes the closed-loop gain of an inverting (Av = −Rf/Rin) or non-inverting (Av = 1 + Rf/Rin) amplifier from the feedback and input resistors, gives the gain in decibels (20·log₁₀|Av|) and the output voltage for an input, and solves the feedback resistor needed for a target gain. The summing endpoint computes the output of an inverting summing (adder) amplifier, Vout = −Rf·Σ(Vi/Ri), from any number of weighted inputs — the basis of analogue mixers and digital-to-analogue converters. The bandwidth endpoint applies the gain-bandwidth product, GBW = closed-loop gain × bandwidth, and solves any of the three (a 1 MHz op-amp at a gain of 10 has a 100 kHz bandwidth), and computes the full-power bandwidth from the slew rate and the peak output voltage, f = slew_rate/(2π·Vpeak). Everything is computed locally and deterministically, so it is instant and private. Ideal for analogue-electronics and circuit-design tools, amplifier, filter and sensor-conditioning design, audio and instrumentation apps, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is op-amp amplifier design; for Ohm's law, reactance and resonance use an Ohm's-law API.

api.oanor.com/opamp-api

Rectifier ripple and smoothing-capacitor maths as an API, computed locally and deterministically. The ripple endpoint computes the peak-to-peak ripple voltage left on a reservoir (smoothing) capacitor after a rectifier, Vr = I_load/(f_ripple·C), where the ripple frequency is the line frequency for a half-wave rectifier and twice it for a full-wave or bridge rectifier — and it solves for whichever of the load current, the capacitance or the ripple you leave out, also giving the RMS ripple. The capacitor endpoint sizes the smoothing capacitor for a target ripple, C = I_load/(f_ripple·Vr), and the energy it stores. The output endpoint gives the DC output of the rectifier from the transformer RMS voltage: the peak Vrms·√2, minus the diode drops in the conduction path (one for half-wave and centre-tapped, two for a bridge), the average DC voltage and, given the ripple, the ripple factor. Everything is computed locally and deterministically, so it is instant and private. Ideal for power-supply and electronics-design tools, linear PSU, charger and audio-amplifier design, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is rectifier ripple and filtering; for Ohm's law, reactance and RC time constants use an Ohm's-law API.

api.oanor.com/rectifier-api

Ideal-transformer relations as an API, computed locally and deterministically. The transformer endpoint works from the turns ratio a = Np/Ns = Vp/Vs = Is/Ip: give any ratio-defining pair — the primary and secondary turns, voltages or currents — and it derives the rest, classifies the transformer as step-up, step-down or 1:1 isolation, and reports the primary and secondary apparent power (which are equal for an ideal transformer, so a step-down in voltage is a step-up in current). The power endpoint applies the power balance with an efficiency, Ps = η·Pp, from the primary or secondary power (given directly or as voltage times current) and reports the power loss. The impedance endpoint reflects an impedance across the transformer, Zp/Zs = (Np/Ns)² = a² — the basis of impedance matching, so an 8 Ω speaker on a 10:1 transformer looks like 800 Ω to the source. Everything is computed locally and deterministically, so it is instant and private. Ideal for electrical and electronics-engineering tools, power-supply and audio-amplifier design, impedance-matching and EE-education apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is ideal-transformer ratios; for Ohm's law, reactance and series/parallel components use an Ohm's-law API.

api.oanor.com/transformer-api

Wheatstone-bridge and strain-gauge maths as an API, computed locally and deterministically. The bridge endpoint takes the four arm resistances R1–R4 and an excitation voltage and returns the bridge output voltage between the two midpoints, Vout = Vin·(R2/(R1+R2) − R4/(R3+R4)), in volts and millivolts, the voltage at each midpoint, and whether the bridge is balanced (Vout = 0 when R1·R4 = R2·R3). The balance endpoint inverts it: give any three arms and it solves the fourth resistance that balances the bridge, the classic way a Wheatstone bridge measures an unknown resistance. The strain endpoint models a strain-gauge bridge — quarter, half or full — and converts in both directions between mechanical strain and electrical output: from a gauge factor and a strain (given directly, as microstrain or as a relative resistance change ΔR/R = GF·ε) it returns the output ratio and voltage Vout/Vin = (k/4)·GF·ε where k is the number of active arms, and from an output voltage and excitation it returns the strain and microstrain. Everything is computed locally and deterministically, so it is instant and private. Ideal for instrumentation and sensor tools, load-cell, pressure-sensor and RTD measurement design, strain-gauge and data-acquisition apps, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is bridge and strain-gauge measurement; for Ohm's law, voltage dividers and series/parallel resistor combinations use an Ohm's-law API.

api.oanor.com/wheatstone-api

Battery and accumulator maths as an API, computed locally and deterministically from basic electrical relationships. The runtime endpoint estimates how long a battery will last under a given load — from the capacity (in mAh, Ah or Wh) and the load (in watts, or amps at a voltage), with adjustable depth-of-discharge and conversion efficiency — and reports the usable energy and the runtime in hours and minutes. The capacity endpoint converts a battery capacity between milliamp-hours, amp-hours, watt-hours, kilowatt-hours and joules at a given voltage. The pack endpoint builds a series/parallel cell pack (for example 3S2P): it returns the pack voltage, capacity and energy and the total cell count — series adds voltage, parallel adds capacity. The charge endpoint estimates the charge time from the capacity and the charge current (or a C-rate), with a charge efficiency and an optional from/to state-of-charge window. Everything is computed locally and deterministically, so it is instant and private. Real-world figures depend on temperature, age, C-rate and the discharge curve, so treat the results as estimates. Ideal for consumer-electronics and IoT tools, solar and off-grid sizing, drone and RC planning, UPS and backup-power sizing, and EV and battery-pack design. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is battery maths; for Ohm's-law voltage/current/resistance use an electronics API.

api.oanor.com/battery-api

Electronics circuit maths as an API. The ohms-law endpoint takes any two of voltage, current, resistance and power and returns all four (V = IR, P = VI = I²R = V²/R). The combine endpoint computes the total of resistors, capacitors or inductors wired in series or parallel — resistors and inductors add in series and combine reciprocally in parallel, while capacitors do the opposite. The voltage-divider endpoint computes the output voltage of a two-resistor divider and the current through it. The reactance endpoint computes capacitive reactance (Xc = 1/2πfC), inductive reactance (XL = 2πfL), the LC resonant frequency, and the RC or RL time constant. Everything is computed locally with exact formulas in SI units, so it is instant and private. Ideal for electronics design and education, embedded and hardware engineering, hobby and bench projects, and physics teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. This is circuit maths; for resistor colour codes use a resistor API and for general unit conversion use a unit API.

api.oanor.com/ohmslaw-api

Read and write resistor colour codes and snap values to the standard E-series. The decode endpoint takes the colour bands of a 3-, 4-, 5- or 6-band resistor and returns the resistance in ohms (nicely formatted as Ω/kΩ/MΩ/GΩ), the significant digits and multiplier, the tolerance, the minimum and maximum resistance that tolerance implies, and — for 6-band parts — the temperature coefficient in ppm/K. The encode endpoint goes the other way: give it a resistance in ohms (and optionally a band count and tolerance) and it returns the colour bands, picking the nearest value representable with the available significant digits. The eseries endpoint snaps any value to the nearest preferred resistor value in the E6, E12, E24, E48 or E96 series and reports the percentage error and the neighbouring preferred values. It uses the standard IEC 60062 colour assignments (including gold ×0.1 and silver ×0.01 multipliers and the implicit ±20% of a 3-band part). Everything is computed locally and deterministically, so it is instant and private. Ideal for electronics design, PCB and BOM work, lab and hobby bench use, repair and reverse-engineering, and teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is for resistor colour codes; for general number formatting use a number-format API.

api.oanor.com/resistor-api