Abstract: An electric drill safety device is provided for dynamically braking a drill when there is contact between the drill bit and an electrically conductive material. A first direction voltage is applied to the motor winding to turn the motor forward. When contact is detected between the drill bit and an electrically conductive material, voltage to the windings is discontinued momentarily and thereafter a reverse direction voltage is provided to the motor windings for a predetermined time.

Abstract: An alarm system is provided in which an alarm condition causes a cellular transceiver automatically to transmit a telephone call to an alarm monitoring station by over-the-air transmission of a signal to a cellular site. A computer at the cellular site will cause communication between the cellular transceiver and an alarm company monitoring station. The alarm system includes a digital communicator with an alarm signal line connected to the digital communicator. The digital communicator is coupled to a cellular transceiver having a programmed keyboard, an audio input and an audio output. The digital communicator has an audio output and an interrogation input. The digital communicator's audio output is coupled to the cellular transceiver's audio input. The cellular transceiver's audio output is coupled to the digital communicator's interrogation input. The digital communicator includes a transmit enable output and a receive enable output.

Abstract: An alarm system is provided in which an alarm condition causes a cellular transceiver automatically to transmit a telephone call to an alarm monitoring station by over-the-air transmission of a signal to a cellular site. A computer at the cellular site will cause communication between the cellular transceiver and an alarm company monitoring station. The alarm system includes a digital communicator with an alarm signal line connected to the digital communicator. The digital communicator is coupled to a cellular transceiver having a programmed keyboard, an audio input and an audio output. The digital communicator has an audio output and an interrogation input. The digital communicator's audio output is coupled to the cellular transceiver's audio input. The cellular transceiver's audio output is coupled to the digital communicator's interrogation input. The digital communicator includes a transmit enable output and a receive enable output.