Abstract: A technique is disclosed for reducing the power consumption of a battery powered cassette player typically including a motor. The technique includes sequentially operating the motor during a first interval (T1) and turning the motor off during a second interval (T2). In the first interval (T1) the motor is driven at a high speed rate. The first interval (T1) and the second interval (T2) are chosen so that the motor is turned off for a longer time period than it is operated to thereby conserve battery power. The technique further includes storing the information from the cassette tape player during the high speed first interval (T1). The stored information is then accessed during the intervals (T1,T2) in order to transfer the information to an output device which causes playback at a lower conventional rate. The technique is preferably implemented by utilizing a controller to perform these functions and an electronic memory device.

Abstract: An intrusion detection system is disclosed including a warning device and a sensor for generating a sensor signal in response to an intruder. A driver coupled between the sensor and the warning device, which is operative to switch from an "off" state to an "on" state in response to the sensor signal. The driver in the "off" state disables the warning device, while in the "on" state the driver activates the warning device. The system further includes a controller for the driver, which includes an oscillator normally in a "static" or unenergized state of operation. The oscillator is activated in response to the sensor signal being continuous for a first predetermined period of time to cause the controller to lock the driver in the "on" state for a second predetermined period of time.

Abstract: A filter circuit smooths the output signal of a digital-to-analog converter by providing linear ramps between adjacent steps of the signal. The circuit measures the voltage difference between two adjacent step levels, amplifies the difference voltage by a predetermined gain, 10 in the present example, then applies the amplified signal to an integrating network having a time constant which is determined by the amplifier gain and the sampling time of the D/A converter. The integrator output signal is summed over the sample period with the converter output signal level of the next preceding sample time period, thereby providing a waveform which has substantially linear transitions between adjacent D/A output levels.