I saw a drill press once from the 1880s. It looked pretty much the same as the ones your old man drools over at Sears sort of delaying your shopping spree when all you wanted to get was a bag clothespins. The main difference is that it's got this huge crank on the side instead of an electric motor.
So I'm wondering what a vibrator from the BE (Before Edison) era might have looked like or worked like.
If you go to Lucerne, Switzerland and checkout the clock tower, you'll find this huge room at the top full of cool stuff, gears and levers and pendulums, all made out of wood and all running more or less by themselves. So from that we can deduce that medieval Europeans knew how to build machines that ran by themselves, or at least enormous cuckoo clocks.
Ok, so now we have a source of power for our medieval vibrator although it's a little too conspicuous for doing private type things. Maybe if we could make it smaller like something you can windup instead of using weights dropping on ropes?
Ok, well I'm no engineer, just in case there was any doubts about that, so I'm not going to get into detailed calculations here. Instead I think we'll just surge ahead because I figure somebody must have devised some sort of a windup thing that we could use to power our vibrator so we don't have to tap into the village clock and get our bells rung both ways.
So I'm imagining this medieval chic kind of wedging her windup vibrator into her chastity belt and cranking away.
'Oh... uh... uuuuhh... oooo... aaaahhhh... *click... wind wind wind*... oh... uh... uuuuhh... oooo... aaaahhhh... oh gawd... *click* shiii... *wind wind wind* oh... uh... '
Ok so maybe you can see now that this thing has a design flaw. It tends rundown, at the wrong time, which probably explains why you don't see many of them in the museums next to the chastity belts that don't need to be rewound.
So that should make you feel pretty lucky to be living in the EE (Edison Era) when we can just flip a switch and experience eternal bliss, until the batteries rundown, shiiii... where did I put the spares?