Why is the current negative in this circuit?

I have a (probably silly) question about this simple series circuit. Why does it show the current as being negative when I run the time domain simulation? I would have thought the current would be positive when the voltage is positive (and above the diode's forward voltage rating). Sorry if this question is too basic but I am trying to teach myself.


by NigelTufnel
July 10, 2014

it depends on what node you click on, try clicking where I marked. http://imgur.com/eyDUkgJ when clicking a node it the current direction is from the wire into the component.

by Garrett
July 10, 2014

Garrett, your suggestion worked. Thank you for clarifying this for me!

by NigelTufnel
July 10, 2014

I am new to Circuitlab and a novice in electronics. When I try to click on a wire to make the current an output in a DC simulation it doesn't show up as an output. Am I doing something wrong or could it be my software. I am running windows 8.1. I would appreciate any suggestions.

by rbgrant
August 25, 2014


To measure a current, you need to click on the ends of a component rather than on a wire.

When you hover the mouse over any component, grey discs will appear where the component pins join the connecting wires.

When you hover the mouse over these discs, their description is shown in the lower right of the Editor window.

To measure a current, you must click on one of these discs.

Noting Garretts comments, the current flowing from the wire into a component pin is shown as positive. Hence a negative current means that the current is flowing out of the component pin into the wire connected to it.

by signality
August 26, 2014


Thank you for your suggestion on recording current as an output. Interestingly when I tried your suggestion using Internet Explorer as a browser it didn't work. I then tried it with Google Chrome and it did work. Thank you.

by rbgrant
August 26, 2014

CL isn't designed to run on IE. It requires a standards compiant HTML5 capable browser:



by signality
August 27, 2014

Thank you. It works fine with google chrome.

R.B. Grant

by rbgrant
August 30, 2014

Post a Reply

Please sign in or create an account to comment.

Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.