# How to make a triangle wave "on paper"?

#### paultwang

Joined Mar 8, 2006
80
I need to simulate a circuit using OrCAD. The problem is I don't have a triangle wave voltage source. All components are ideal so generators based on noise oscillation do not work. Please recommend a method to generate triangle wave at specified frequency.

#### JoeJester

Joined Apr 26, 2005
4,390

#### Papabravo

Joined Feb 24, 2006
21,314
Originally posted by paultwang@Apr 19 2006, 11:41 PM
I need to simulate a circuit using OrCAD. The problem is I don't have a triangle wave voltage source. All components are ideal so generators based on noise oscillation do not work. Please recommend a method to generate triangle wave at specified frequency.
[post=16348]Quoted post[/post]​
In the real world:
What is the integral of a step function? A ramp!
What is the integral of a negative step function? A negative ramp!
Put a positive step and a negative step together and you have a square wave.
Integrate the squarewave and you'll get a triangle wave, almost certainly.

In the simulated world:
You can specify a pulse generator with a very long rise time and a very long fall time and a frequency such that the rise time is half the period and the fall time is half the period, and behold the magical mystical TRIANGLE wave.

Very clever these simulators.

#### Mazaag

Joined Oct 23, 2004
255
Originally posted by paultwang@Apr 19 2006, 10:41 PM
I need to simulate a circuit using OrCAD. The problem is I don't have a triangle wave voltage source. All components are ideal so generators based on noise oscillation do not work. Please recommend a method to generate triangle wave at specified frequency.
[post=16348]Quoted post[/post]​
I was thinking maybe you could make a square wave relaxation oscillator, then feed it into an integrator. Yes I know the opamp requires noise to start of.. what you could do is put a voltage source with a very small value (say micro volts) into the non-inverting terminal. That will give you the intial rail voltage required to start up the relaxation oscillator...

Papa please tell me if anything I said up there makes sense ....

paul don't read anything I said up there till Papa says its okay to..

#### Papabravo

Joined Feb 24, 2006
21,314
Originally posted by Mazaag@Apr 21 2006, 02:39 PM
I was thinking maybe you could make a square wave relaxation oscillator, then feed it into an integrator. Yes I know the opamp requires noise to start of.. what you could do is put a voltage source with a very small value (say micro volts) into the non-inverting terminal. That will give you the intial rail voltage required to start up the relaxation oscillator...

Papa please tell me if anything I said up there makes sense ....

paul don't read anything I said up there till Papa says its okay to..
[post=16386]Quoted post[/post]​
Fine by me