Electronics & RF calculators
Choose a task below. Check each calculator’s assumptions and units before using its result.
Quarter-Wave Transmission Line Impedance Matching Calculator
Calculate characteristic impedance (Zmatch), physical cut length, velocity factor correction, and operating bandwidth for λ/4 impedance matching lines.
Quarter-Wave Transmission Line Transformer Calculator
Calculate the required characteristic impedance (Z0) and exact physical cutting length for quarter-wave (λ/4) RF impedance matching sections.
Quartz Crystal Oscillator Load Capacitance & Pierce Margin
Calculate quartz crystal load capacitors ($C_{L1}, C_{L2}$), Pierce oscillator negative resistance ($|-R|$), oscillation safety margin ($SF \ge 5$), and drive level.
RF Circulator & Isolator Power Dissipation Calculator
Size termination dump loads ($P_{dump} = P_{fwd} \cdot |\Gamma|^2$), calculate forward insertion loss, reverse isolation, and protect high-power RF transmitters from antenna mismatches.
RF L-Network Impedance Matching Calculator | AnythingOnline
Free RF L-network matching calculator. Calculate inductance (L), capacitance (C), loaded Q, and circuit topology to match complex load impedance to 50 ohms.
RF Link Budget & Friis Free Space Path Loss Calculator
Calculate Free Space Path Loss (FSPL), received RF power ($P_{rx}$), receiver thermal noise floor, and fade margin (dB) for wireless IoT, cellular, and satellite links.
RF Mixer Intermodulation Spurs & IMD Table Calculator
Map all $(m \cdot f_{RF} \pm n \cdot f_{LO})$ intermodulation products up to 5th order. Identify critical in-band IF spurious responses and compare high-side vs low-side LO injection.
RF Return Loss Bridge & Reflection Coefficient Calculator
Calculate RF Wheatstone return loss bridge balance, complex reflection coefficient ($\Gamma$), return loss (dB), VSWR, and directivity measurement limits.
RF SWR, Return Loss & Reflection Coefficient Calculator
Instant bidirectional conversion between VSWR, Return Loss (dB), Reflection Coefficient (Γ), mismatch loss, and transmitted power.
RS-485 / RS-422 Differential Bus Termination & Fail-Safe
Size line termination resistors (120Ω) and fail-safe pull-up/pull-down bias networks. Prevent floating UART frame errors and maintain +200mV differential noise margin.
Soil Resistivity Calculator - Wenner Four-Pin Method
Calculate apparent soil resistivity (ρ in Ω·cm and Ω·m) from Wenner four-pin field resistance measurements and classify soil corrosiveness per ASTM G57 and NACE standards.
Solar Backfeed Breaker Calculator - NEC 120 Percent Sizing
Determine maximum allowable solar PV backfeed circuit breaker size and panelboard busbar ampacity limits under NEC 705.12(B) load-side interconnection rules.
Solar String Voltage Calculator - PV Temperature Sizing
Calculate maximum cold-weather string Voc per NEC 690.7 and summer hot Vmp to ensure strings never exceed inverter maximum DC voltage ratings.
Step and Touch Voltage Calculator - IEEE 80 Safety Limits
Determine IEEE Std 80 tolerable step and touch voltage human safety thresholds based on crushed rock surface layer resistivity, body weight, and clearing time.
Submersible Well Pump Wire Size & Voltage Drop Calculator
Calculate required submersible copper cable gauge (AWG), terminal voltage drop, and backup generator wattage for deep well pump motors.
Substation Ground Grid Calculator - IEEE 80 Resistance
Determine substation ground grid resistance (Rg) and Ground Potential Rise (GPR) using Sverak and Laurent-Nieman equations per IEEE Std 80.
Substrate Integrated Waveguide (SIW) Cutoff Calculator
Synthesize low-loss planar waveguides on PCB substrates, calculate Cassivi equivalent widths, TE10 mode cutoff frequencies, and verify via pitch radiation leakage rules.
Synchronous Buck Bootstrap Capacitor Calculator
Size bootstrap capacitors, damping resistors, and calculate minimum low-side refresh times and maximum duty cycle limits to prevent high-side gate UVLO dropout.
Three-Phase Bolted Fault Calculator - Symmetrical KA Sizing
Determine maximum available symmetrical fault current at transformer terminals and downstream panelboard buses using the IEEE point-to-point method.
TL431 Shunt Regulator & Voltage Reference Resistor
Calculate feedback voltage divider resistors (R1/R2), ballast cathode resistor, and power dissipation for TL431 and TLV431 precision adjustable shunt regulators.
Transformer Inrush Current Calculator - Primary Fuse Sizing
Compute transformer magnetizing inrush current peaks (8x to 14x FLA at 0.1s) and size primary and secondary overcurrent protection per NEC Table 450.3.
Transformer KVA Calculator - Single & 3-Phase Amperage
Calculate transformer kVA rating, primary and secondary full-load current (FLA), and overcurrent protection sizing for 1-phase and 3-phase systems.
Transformer Proximity Effect Calculator
Model high-frequency eddy current winding losses using Dowell's equation, evaluate layer porosity factors, and quantify interleaving copper loss reduction.
UART Baud Rate Error & Clock Divider Calculator | AnythingOnline
Free UART baud rate error calculator. Calculate integer and fractional clock dividers (BRR), actual baud rate, and percentage timing error for STM32, AVR, and ESP32.
VFD Cable Length Calculator - Reflected Wave dv/dt Sizing
Compute transmission line critical cable length, peak motor terminal voltage doubling (Vpeak), and dV/dt filter requirements per NEMA MG-1 Part 31.
VFD Energy Savings Calculator - Payback Period Sizing
Compute electrical kilowatt reduction, annual kWh savings, and simple payback period for VFD retrofits on centrifugal pumps and fans using affinity cubic laws.
Voltage Drop Calculator - Single & 3-Phase Wire Sizing
Calculate AC/DC circuit voltage drop percentage, end-of-run voltage, and find the minimum wire size to stay within NEC 3% standards.
Waveguide E-Plane, H-Plane & Magic Tee Calculator
Analyze 3-port E-plane series and H-plane shunt junctions, evaluate 4-port Magic Hybrid Tees, compute TE10 guide wavelengths, and size inductive matching posts.
Wire Ampacity Calculator - NEC Gauge & Conduit Sizing
Determine allowable ampacity for copper and aluminum conductors according to NEC tables, temperature correction, and conduit bundling deratings.
Zener Diode Voltage Regulator & Resistor Sizing Calculator | AnythingOnline
Free Zener diode voltage regulator calculator. Calculate series resistor (Rs), power dissipation, and diode wattage rating under varying DC input voltages.