Abstract: A direct connect telephone line interface which includes a solid state off hook phone line load is disclosed. The solid state off hook phone line load utilizes an active semiconductor device coupleable between the phone lines, with the control input to the active semiconductor device being coupled to a bias circuit operative from the voltage across the phone lines to bias the active semiconductor device in saturation as a result of an answer voltage on the phone lines. The bias circuit is frequency selective so that the bias point of the active semiconductor device is substantially independent of information signals on the telephone line.

Abstract: A portable lightweight angle grinder is disclosed having a motor housing with a handgrip and throttle lever, a rotary air motor driving a motor spindle, an elongated air-cooled tubular extension housing adjustably mounted on said motor housing, a work spindle near the end of said extension, toothed pulleys on the work spindle and the motor spindle, and an endless neoprene belt within said extension housing with teeth that mesh with the teeth of said pulleys. The unique toothed belt drive requires no lubrication, operates efficiently at speeds up to 25,000 revolutions per minute and at least twice that normally used in conventional angle grinders using gear drives, and can be maintained in service at a fraction of the cost of the prior devices.