The present invention is directed to a roll-off trucktrailer and a method for weighing the box that is positioned horizontally on the trucktrailer. Previous circuit operations required an additional supply voltage rail, but the preferred embodiment exploits charge sharing to generate a half swing clock with less power and without the additional supply voltage rail. The interior of the outer cylinder may be moveable between an uncocked position and a cocked position such that movement of the outer cylinder from the cocked position toward the uncocked position compresses air in the interior of the outer cylinder, with the compressed air being delivered to through the fluid passage to a toy projectile attached to the toy projectile launcher.