Abstract: A solar tracking device is mounted above a skylight of a building. An array of mirrors is rotated at a rate of one revolution per day to reflect sunlight through the skylight. A control circuit intermittently adjusts the angular position of the tracking device so that the mirrors face the sun. A solar array charges an internal energy storage system so that no external power source is needed. The control circuit within the tracking device reduces the power requirements at night and when not moving the tracking device during the daytime to conserve electrical energy.

Abstract: A solar tracking device is mounted above a skylight of a building. An array of mirrors is rotated at a rate of one revolution per day to reflect sunlight through the skylight. A control circuit intermittently adjusts the angular position of the tracking device so that the mirrors face the sun. A solar array charges an internal energy storage system so that no external power source is needed. The control circuit within the tracking device reduces the power requirements at night and when not moving the tracking device during the daytime to conserve electrical energy.

Abstract: A solar tracking device is mounted above a skylight of a building. An array of mirrors is rotated at a rate of one revolution per day to reflect sunlight through the skylight. A control circuit intermittently adjusts the angular position of the tracking device so that the mirrors face the sun. A solar array charges an internal energy storage system so that no external power source is needed. The control circuit within the tracking device reduces the power requirements at night and when not moving the tracking device during the daytime to conserve electrical energy.

Abstract: A solar tracking device is mounted above a skylight of a building. An array of mirrors is rotated at a rate of one revolution per day to reflect sunlight through the skylight. A control circuit intermittently adjusts the angular position of the tracking device so that the mirrors face the sun. A solar array charges an internal energy storage system so that no external power source is needed. The control circuit within the tracking device reduces the power requirements at night and when not moving the tracking device during the daytime to conserve electrical energy.

Abstract: A speaker telephone comprising a microphone outputting an electrical signal, and a loudspeaker is disclosed. An amplifier has its output coupled to the loudspeaker. This amplifier has non-inverting and inverting inputs. A switch having two positions couples the microphone to the amplifier or couples the tuning signal source to one of the inputs of the amplifier. A tuning signal source and control circuit output a tuning signal. Initiation means initiates a tuning sequence by causing the switch to be in the second position and causing the tuning signal source and control circuit to generate tuning signals. A coupling device is connected to one of the inputs of the amplifier and adopted to be connected to a telephone circuit. A hybrid voltage generator circuit is responsive to the output of the microphone when the switch couples the microphone to the amplifier to generate at its output a cancellation signal which prevents transmitted voice signals from appearing at the loudspeaker.