http://www.falstad.com/circuit/ http://www.falstad.com/circuit/ https://www.circuitlab.com/ https://www.circuitlab.com/ I recommend LTSpice as a desktop circui

http://www.falstad.com/circuit/ http://www.falstad.com/circuit/ https://www.circuitlab.com/ https://www.circuitlab.com/ I recommend LTSpice as a desktop circuit simulator/analyzer.