A simple LM324 squarewave and sawtooth generator with triangle to adjustable duty cycle pulse output.
Triangle output is roughly linear by being set to a small section of an exponetial charge and discharge.
**How it works:**
The actual oscillator is made up of the components around U2. See "Figure 27. Squarewave Oscillator" in: http://www.ti.com/lit/ds/symlink/lm124-n.pdf
U1 just gener...