Learning embedded development and mastering essential hardware circuit knowledge is very important. The author previously introduced the free tool LTspice provided by Analog Devices in the article “Key Technologies in Embedded Development at a Glance”. It is quite good, available for free download (it is very small in size), has a rich device library, many examples, and can simulate and view waveforms, making it very worthwhile to try. Today, I will introduce a software that has similar functionality to Proteus software, allowing online design and modification of circuits, simulating and viewing voltage and current waveforms at various points, but it is a web-based tool that does not require downloading. The website is: https://falstad.com/circuit/circuitsjs.html
This is a 7-segment decoder connected to a 7-segment LED display:
This is an analog signal adder:
You can also directly operate on the webpage to try it out. You can transfer both digital circuits and analog circuits from books to the webpage, modify the parameters of the components to see the effects, and what you see is what you get, which is very convenient for understanding and using circuits.