# creating a square wave with + - amplitude

#### lostwithcircuits

Joined Feb 6, 2012
1
I need some help as I am a beginner with circuits. My end goal is to create a square wave with +-amplitude with pulse width of 5ms. I am using an arduino and command PWM to generate the two single sq waves (+5V to -0V) and (-5V to -0V) but I do not know how to combine the two outputs to create a single +-5V sq wave.
Thanks!

#### wayneh

Joined Sep 9, 2010
16,400
Are the two waves already related to each other through time, or is the comparison what you're looking for? If they're not related, you've really got a 3-state, 10V wave. You can have one at -5 and the other at +5 for ∆V=10, or they can be the same with ∆V=0, or the reverse of above, ∆V=-10.

More detail about what you want will get you a good answer here.

#### castley

Joined Jul 17, 2011
31
A 741 Op Amp with + - 5V supply should give you the output you need. If one input is set at + 2.5 volts and you feed a 0 to +5 V SQ. wave in The output will be 0 when the input is + 2.5 V.

#### Ron H

Joined Apr 14, 2005
7,014
A 741 Op Amp with + - 5V supply should give you the output you need. If one input is set at + 2.5 volts and you feed a 0 to +5 V SQ. wave in The output will be 0 when the input is + 2.5 V.
No it won't.
Lostwithcircuits, Are the three waveforms identical except for voltage levels? If not, we need a drawing of your two inputs and the desired output.