Transistorgrab

One who needs to simulate a circuit will sooner or later stumple across SwitcherCAD. This article shows how to generate a saw tooth or triangular voltage.

The company Linar Technology provides on its web site the tool SwitcherCAD for free.
It is a Spice base simulation tool that is uses to simulate curcuits. Unfortunatly it is only available for the Windows platform.

Generations Of Saw Tooth Or Triangular Voltages

From the component dialog choose a voltage source “voltage” and place it in the schematic with OK.

With a right click on the voltage source in the schematic open the dialog für the voltage source.

In this dialog click on Advanced to open the advanced dialog.
Choose the function “PULSE”. To generate a saw tooth the parameters “T rise” “T fall” “T on” and “T period” are important.
For this example we want to generate a saw tooth with 20 Hz.
“T period” needs to be 50 ms.
“T rise” could be set to 50 ms and “T on” and “T fall” to 0, but this can leed to strange simulation results. It has been proved to set “T on” and “T fall” at least to 1 ns and substract this times from “T on”. The result must be entered for “T raise”. Of course you need to enter a value for “Von” higher than 0 to have a voltage that can be measured.

The result should then look like this:

To generate a triangular volage only a little modification is necessary. “T raise” will be set to 25 ms, “T on” to 0 and “T fall” will also set to 25ms.