A: It is a pulse of any duration designed to trigger an event i logic design

Pulse the door trigger right before unlock, or set up for double pulse unlock, and diode isolate the door unlock wire from the door trigger wire.

it should produce a trigger pulse at a time.

Pulse transformers are designed to accurately reproduce signals with fast rise-times. They are not very good at reproducing normal sinusoidal AC signals. Pulse transformers are used to trigger SCR's, for instance, in motor controls and lamp dimmers. If you open up a photoflash unit, you will most likely see a small pulse transformer used to trigger the high-voltage pulse to the Xenon photoflash tube.

A clock input is a regular periodic pulse that can be used as a trigger to sequence timing-important activities.