Abstract: A method and apparatus for analyzing movement of objects in a border area. Information about the movement of the objects in the border area is identified from sensor data. The information about the movement of the objects in the border area is compared with movement information for the border area to form a comparison. An alert is generated when the comparison indicates that an object of interest in the objects is present.

Abstract: A power tool has a variable speed control circuit that comprises a user switch, a motor and a silicon controlled rectifier (SCR) connected in series between a pair of power supply terminals. A manually variable resistor is connected between a first electrode of the SCR and a circuit node. A capacitor is coupled between the circuit node and a second SCR electrode. A bleed-off resistor is connected between second electrode of the SCR and the circuit node to provide a path for discharging the capacitor when the user switch is open. A zener diode couples the circuit node to the SCR gate electrode. The circuit configuration ensures that the capacitor charges from substantially the same voltage level at the start of each half-cycle during which the SCR is to be turned on.