I am a recent tech school grad and am trying to build a pulse generator for final testing of my company`s product. The pulse generator would simulate a flywheel which is supplied by the customer at their site so you see my need for this project. I have been thinking about a simple 555 timer circuit connected to a transistor(if necessary) switching a relay, passing 24v to the input of a plc. the 24v is already supplied by a power supply. Any ideas? Has anyone worked with this circuit? It does`nt have to be the said circuit, just an on, off, on, off.