Circuits Cloud Is Now Open Circuits: A Free Circuit Simulator Built for Learning

If you studied electronics any time in the last decade, you may have run into Circuits Cloud, the free online simulator launched in Bahrain in 2014 and featured in plenty of "best online circuit simulators" lists. It has a new name and a new home: Open Circuits, at opencircuits.net.

This post explains what changed, what you can do with it today, and how to try it in about five minutes.

From Circuits Cloud to Open Circuits

Circuits Cloud started as an online digital logic simulator built by Script for Information Technology Solutions in Bahrain, and later added analog simulation. It was made for students, and a lot of teachers and hobbyists used it to try circuits before building them.

Open Circuits is the same project, rebuilt. The goal hasn't changed: a simulator that runs in your browser, costs nothing, and is easy enough to use in a first electronics class.

What you can simulate

Digital logic. AND, OR, NOT, NAND, NOR, XOR and XNOR gates, tri-state buffers, SR, JK, D and T flip-flops, multiplexers, decoders, encoders, adders, clock generators, 7-segment displays and LED arrays.

Analog circuits. Resistors, capacitors, inductors, potentiometers, DC sources, diodes, LEDs, Zener diodes, NPN and PNP transistors and op-amps. The analog engine uses Modified Nodal Analysis, the same approach SPICE simulators use, and you can watch current flow along the wires and place voltage and current probes.

Microcontrollers. Arduino UNO, Nano, Mega 2560 and Pro Mini running real sketches, with common libraries such as Servo, LiquidCrystal, SSD1306, NeoPixel, DHT and Keypad. It also simulates PIC16F877A, PIC16F887, PIC16F876A, PIC16F628A, PIC16F84A and PIC12F675 chips, programmed in C, assembly or Intel HEX, with timers, PWM, ADC, USART and interrupts.

Plug-in parts. LCD and OLED displays, servos, buzzers, RGB LEDs, NeoPixel strips, and sensors such as the HC-SR04, DHT22, LM35, light and PIR sensors. You can drag a sensor's value or turn a knob while the program is running and see the result immediately.

Built for teaching

Most simulators stop at the canvas. Open Circuits adds three things for classrooms:

1. Recorded lessons. The Academy has 61 step-by-step lessons on logic gates, combinational and sequential circuits, digital system design, DC circuit analysis, and AC and transients. Each one is a recording of a circuit being built, which students can pause, rewind and replay at their own speed.
2. Your own recordings. Teachers can record every action on the canvas with voice narration and publish it as a lesson.
3. Classes and assignments. Create class groups, invite students by email or code, set circuit challenges with due dates, then review, grade and comment on what students submit.

The interface is available in 15 languages, including English, Arabic, Chinese, Spanish, Hindi, French and Portuguese.

Try it in five minutes

1. Go to opencircuits.net. There's nothing to install.
2. Open the Circuit Library and choose a ready-made example, such as a half-wave rectifier from the op-amp section.
3. Press Run. Current animates along the wires, and the graph inspector plots the input sine wave against the rectified output.
4. Change a resistor value or swap a diode, run it again, and compare the waveforms.
5. When you're ready, fork the example to your own workspace and build from there.

Who it's for

• Students who want to check a homework circuit or see how a flip-flop really behaves.
• Teachers who want to demonstrate circuits live and set practical work without a lab.
• Makers who want to test an Arduino or PIC project before wiring anything.

Open Circuits is free to use. If you used Circuits Cloud before, this is where the project lives now. We'd love feedback on what to add next.

Try it: opencircuits.net

Disclosure: this article was written by the Open Circuits team.