A TRAPEZOIDAL WAVE looks like a sawtooth wave sitting on top of a square wave. The leading
edge is called the JUMP voltage.
A TRIGGER is a very narrow pulse used to turn on or off another circuit.
A MULTIVIBRATOR is used to generate a square or rectangular wave. A multivibrator is
basically two amplifiers with regenerative feedback.
The ASTABLE MULTIVIBRATOR has no stable state. The transistors alternately switch from
cutoff to saturation at a frequency determined by the RC time constants of the coupling circuits.