A pulse is nothing more than applying power for a short period of time. The solenoid will have a mimimum actuation time in order to operate. In addition, it will take some time (short, but still some time) for the gate to be pulled by the spring and start moving. Therefore, the "pulse" of power to the solenoid must be at least as long as those two actions take. In this application, the easy way out is to make the pulse a second or two long, because there is no penalty for a pulse that is too long."and the solenoid could be pulsed (via a MOSFET) "
Oh, I love it when you talk techie to me. Of course, I don't have a clue as to what that means. My understanding is that the solenoid needs but one "pulse" to pull it open/back and release the door/gate.
Honestly, I do not understand the pulse thing.
I don't know what you have in mind for the latch mechanism, and I know you said you could handle it, but I hope you aren't planning to have the plunger of the solenoid act as a striker that hits a latch when the gate shuts. I think that would put too much lateral pressure on the solenoid, and unless it's bigger than I imagine, it wouldn't hold up well. I suppose that you also know that solenoids are made to actuate by electromagnetics, but they usually rely on a spring mechanism to "un actuate," and the spring usually doesn't have as much power as the actuation. Just something to keep in mind as you design the latch.
BTW, if I'm providing more info than you want or need, just say so, and I'll lighten up. I am especially interested in this project because I plan to build a chicken coop and run next spring, and plan on having some of the functions automated in much the same way as your dog pen.