As i said in my original post, "A dumb circuit without even a single chip in it could do that." Vibration units can literally just respond to voltage. It's how electrical devices worked before chips, like old pinball machines and old radios. It works just like how a standing fan works - there's a mechanical motor, and you literally just need to attach plain copper wires onto the motor's contact points and stick the other ends of the wire into the slots of a wall power outlet.

You don't need a chip in a vibration circuit. Hell a potentiometer is more than sufficient to give you different levels of vibration