Circuit Simulations
Change the values and see instantly how the circuit responds. Try it here before you burn something out on a real board.
1. LED and series resistor
The resistor sets how much current flows through the LED. The LED burns out above 30 mA.
I = (V − VLED) / R = (9 − 2) / 470 = 14.9 mA
2. Voltage divider
Get any fraction of a voltage you want with two resistors. Common when reading sensors.
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All simulators (59)
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LED and series resistor
Change the voltage and resistance and see the LED current. Go over 30 mA and the LED burns out.
🔒 repair packVoltage divider
Get any fraction of a voltage with two resistors.
🔒 repair packOhm's Law
Explore V = I × R by changing the values.
🔒 repair packElectron flow in a conductor
See how electrons move through a conductor when a voltage is applied.
🔒 repair packUnit and prefix converter
Convert between units such as mA, kΩ and µF.
🔒 repair packSeries and parallel resistors
Connect resistors in series or parallel and see the equivalent resistance and currents.
🔒 repair packKirchhoff's laws
Calculate node currents and loop voltages live.
🔒 repair packElectrical power and heating
See the power dissipated in a resistor and how it heats up.
🔒 repair packCells and batteries
How do voltage and capacity change with series and parallel cells?
🔒 repair packShort circuits and fuses
What happens to the current in a short circuit, and how does a fuse protect?
🔒 repair packAlternating current (AC)
Explore peak, RMS value and frequency of a sine wave.
🔒 repair packLDR and NTC sensors
Try light- and temperature-dependent resistors in a voltage divider.
🔒 repair packRC charge and discharge
See the capacitor charging curve and the time constant.
🔒 repair packRelay
See how the contacts switch when the coil is energized.
🔒 repair packDiode
Try the diode in forward and reverse bias.
🔒 repair packTransistor switch
Control the collector current with the base current.
🔒 repair packMultimeter
Measure voltage, current and resistance with a virtual multimeter.
🔒 repair packBreadboard
Build circuits on a breadboard and spot the common mistakes.
🔒 repair packTroubleshooting: LED circuit
Measure test points with a multimeter and diagnose the hidden fault.
🔒 repair packGood and bad solder joints
Compare cross-sections of solder joints.
🔒 repair packTwo-transistor flasher
Watch the LEDs blink in an astable multivibrator.
🔒 repair packComponent test bench
Test parts with a multimeter; find the faulty one in fault-hunt mode.
🔒 repair packTesting parts on diode mode
Diode and transistor readings on the multimeter's diode mode.
🔒 repair packCapacitor ESR
See how ESR in an ageing capacitor affects ripple.
🔒 repair packShort-circuit hunt
Find the shorted capacitor by measuring voltage drop along the rail.
🔒 repair packTransistor switch designer
Calculate the base resistor for your load and check saturation.
🔒 repair packMOSFET
See the MOSFET turn on as the gate voltage rises.
🔒 repair packHeat and heatsink calculator
Calculate junction temperature and the heatsink from power loss.
🔒 repair packRectifier and filter
Half- and full-wave rectification, filter capacitor and ripple.
🔒 repair packLinear regulator
Input voltage, dropout and heat loss in a 7805.
🔒 repair packLM317 calculator
Set the LM317 output voltage with two resistors.
🔒 repair packBuck and boost converter
See how the output voltage changes with duty cycle.
🔒 repair packOp-amp circuit simulator
Inverting, non-inverting, summing, Schmitt and more; see input and output over time.
🔒 repair packActive filter (Bode)
Frequency response of low-pass and high-pass filters.
🔒 repair packOp-amp relaxation oscillator
Generate a square wave with a Schmitt trigger and RC.
🔒 repair pack555 timer
Set the 555 frequency and duty cycle with resistors and a capacitor.
🔒 repair packLogic gates
Try AND, OR, NOT and XOR gates and see the truth table.
🔒 repair packKarnaugh map
Simplify Boolean expressions with a Karnaugh map.
🔒 repair packBinary adder
Add binary numbers with half and full adders.
🔒 repair packLatches and flip-flops
See how SR, D and JK flip-flops change with the clock.
🔒 repair packCounter
Binary counting and frequency division with flip-flops.
🔒 repair packElectronic dice (CD4017)
Build a die face with a counter IC and diodes.
🔒 repair packBinary, hex and ASCII converter
Convert numbers and characters to bits.
🔒 repair packUART
Watch start, data and stop bits one by one.
🔒 repair packI2C
Watch address, data and ACK bits on SDA and SCL.
🔒 repair packSPI
See MOSI, MISO, SCK and CS signals step by step.
🔒 repair packArduino simulator
Write and run Arduino code in your browser: LEDs, buttons, potentiometers, servos, serial monitor.
🔒 repair packPCB trace width calculator
Calculate trace width from current and temperature rise (IPC-2221).
🔒 repair packCapacitor code decoder
Turn codes such as 104 and 473 into values.
🔒 repair packTimer1 CTC calculator
Get the frequency you want with the prescaler and compare value.
🔒 repair packADC calculator
Calculate ADC readings from the reference voltage and resolution.
🔒 repair packBattery life calculator
Estimate battery life from sleep and active currents.
🔒 repair packH-bridge
Reverse a motor with four switches and see the shoot-through case.
🔒 repair packGate drive and losses
Calculate MOSFET losses against switching frequency.
🔒 repair packTriac phase control
Adjust the power to a lamp with the firing angle.
🔒 repair packInverter waveforms
Compare square, modified sine and PWM sine outputs.
🔒 repair packBuck / boost design bench
Calculate the inductor, capacitor and ripple.
🔒 repair packFlyback calculator
Calculate the turns ratio and switch voltage.
🔒 repair packControl loop: load step
See how the feedback tuning affects the output response.