[sdiy] Square to Saw converter? (5Pulser abuse)

[RFahl]

Looking at Ian Fritz's 5Pulser, I started thinking that it might be cool to
turn this into sort of a burst generator... that is it would take a square
wave in and create multiple pulses depending on the control voltage.  The
input is looking for a saw wave, so unless this thing will work with a
square wave as is... how do I convert a square wave into a sawtooth wave?

Romeo