Abstract: A monitoring system uses a portable master unit and at least one portable slave unit. The master unit provides an electrical circuit including an antenna, an RF signal amplifier, an RF signal tuner, a countdown timer, an attenuator, an adjustable delay timer, an AND gate and an audible alarm. Each of the slave units providing a slave circuit including a transmitter with transmitting antenna and an RF pulse generating circuit. The master unit is adjusted for receiving RF energy transmitted by a slave unit when the units are separated by a target distance or less. A time delay parameter is set using dual timers so that the slave may be positioned beyond the allowable distance parameter for a pre-selected duration before the alarm is triggered.

Abstract: An internal combustion engine provides a piston and a cylinder within which either the piston or the cylinder, or both, are free to move and using constraining motion, either the piston or the cylinder reciprocates. A shaft takeoff integral with either the piston or the cylinder experiences rotational motion. The motion is constrained by using laterally extending tits of either the piston or the cylinder to move in curilinear grooves of the other or of a housing encompassing the cylinder.

Abstract: A socket tool apparatus comprises a body having a central axis and opposing end surfaces. Impressed into one of the end surfaces are plural, central axis concentric, non-round, apertures of sequentially diminishing size. At the other one of the end surfaces, an aperture or a rod is positioned for attachment of the socket tool to a driver tool so as to enable the socket tool to revolve about the central axis. A spring is used to apply holding force to a fastener inserted into the socket tool.