Hi Wmerz, Welcome to EasyEDA. For information about and examples of using the PULSE source in EasyEDA, please see: https://easyeda.com/Doc/Simulation-eBook/Configuring-Voltage-and-Current-Sources.htm#Configuring-Voltage-and-Current-Sources If you click on a source you can see the parameters in the right hand Properties panel: ![enter image description here][1] You can also edit the parameters directly by double-left-clicking on the `PULSE(-1 1 0m 100u 200u 400u 1000u) AC 1 0` text: ![enter image description here][2] Note: Please replace the `EasyEDA` Source that you have used for V2 in your tachometer: the parameters for these Sources do not work as expected. The standard spice Sources described in the Simulation eBook are far more versatile anyway. [1]: /editor/20160422/5719d35e1b2f6.png [2]: /editor/20160422/5719d3ba1be40.png