Need a square wave at a relatively low frequency?  Here is a circuit that you can use to generate a symmetrical square wave.

• Assuming R₁ = R₂, the output is a symmetrical square wave with an amplitude equal to the saturation level of the op-amp.
• The frequency of oscillation is given by:
• f = 1/[2ln(3)RC]
• The output resistance/impedance is low since the output is the output of the operational amplifier.
• The high frequency limit is determined by the slew rate of the op-amp.