Circuit Notebook calculators
Calculators that draw your circuit
Type your values. It draws your circuit with them, picks the real part you can buy, shows the working, and drops it in your notebook in one click.
Open the calculators Opens in the app on 1 December, with Circuit Notebook 1.0 The formulas are already here.
Basics Resistors, LEDs, dividers, RC: the everyday ones.
- Ohm's law & powerAny two of V, I, R, P give the other two.
- LED resistorThe series resistor, in a value you can buy.
- Voltage dividerWhat two resistors give, loaded or not; or the pair to build one.
- Series & parallelResistors, capacitors or inductors together, and how they share.
- Resistor colour codeA value to its bands, or the bands to a value.
- RC time constantτ, the cutoff, and how long to reach a level.
- Reactance & resonanceXL and XC at a frequency, and where L and C meet.
- Wheatstone bridgeThe output of a bridge, the value that balances it, the unknown from a reading.
- Capacitive dividerTwo capacitors in series: the ratio, the tap, the load that spoils it.
- RL time constantτ = L / R, the final current, and the kick when the switch opens.
- RLC circuitResonance, Q, bandwidth and damping, in series or in parallel.
Power Regulators, converters, heat, batteries.
- Linear regulator heatWhat a 7805 or an LDO burns, its efficiency, how hot it gets.
- Battery lifeHow long a device that sleeps and wakes will run.
- TransformerTurns ratio, secondary voltage, currents, the load seen from the primary.
- Buck converterDuty cycle, inductor, capacitor, the peak currents.Premium
- Boost converterDuty cycle, inductor, capacitor, and the current the input must give.Premium
- Flyback converterTurns ratio, duty, primary inductance and peak currents from the reflected voltage.Premium
- Heatsink & junction temperatureFrom the air to the junction through the thermal resistances; the heatsink you need.Premium
- Zener regulatorThe series resistor, the Zener's heat, the current it wastes.
- Bulk capacitorThe capacitor after a rectifier for a given ripple, or for a hold-up time.
Signals & radio Decibels, filters, op-amps, links.
- Decibels & dBmRatios to dB and back; dBm to watts and volts.
- Wavelength & frequencyλ from f and back, in air or in a cable; the quarter-wave.
- Op-amp gain designerThe resistor pair for a gain, and what limits it: bandwidth, slew rate.Premium
- Sallen-Key filterA second-order low-pass or high-pass from one op-amp: the four parts for a cutoff and a Q.Premium
- Radio link budgetFree-space loss, the power that arrives, the margin and the range.Premium
- LC filterThe corner of an LC low-pass or high-pass, its Q, the peak a light load leaves.
Embedded ADC, timers, PWM: the microcontroller side.
Boards & wires Traces, cables, the copper itself.
- Wire gauge & voltage dropWhat a cable drops over its length, warm, and how hard it is worked.
- PCB trace widthThe width a current needs (IPC-2221), and what the trace drops.Premium
- Microstrip impedanceZ0 of a trace over a ground plane, or the width for 50 Ω.Premium
- Differential pairZdiff of two coupled traces, or the width for 90 or 100 Ω.Premium