Abstract: An acoustic layer is added to a laptop-type personal computing device, comprising: enclosing walls, optionally one or more microphones, a signal processing device, at least one audio transducer, and an acoustic waveguide. The acoustic layer adjoins one or more internal areas of a laptop-type device. The signal processing device receives an internal signal from a laptop-type device. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: An acoustic layer is added to a laptop-type personal computing device, comprising: enclosing walls, optionally—one or more microphones, a signal processing device, at least one audio transducer, and an acoustic waveguide. The acoustic layer adjoins one or more internal areas of a laptop-type device. The signal processing device receives an internal signal from a laptop-type device. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: An acoustic layer is added to a laptop-type personal computing device, comprising: enclosing walls, optionally—one or more microphones, a signal processing device, at least one audio transducer, and an acoustic waveguide. The acoustic layer adjoins one or more internal areas of a laptop-type device. The signal processing device receives an internal signal from a laptop-type device. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: A soundskin for a pad-type device comprises a housing, at least one microphone, a signal processing device, at least one audio transducer, and an acoustic waveguide. The housing receives a pad-type device. The signal processing device receives a signal from a pad-type device when the pad-type device is received by the housing. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: An acoustic layer is added to a laptop-type personal computing device, comprising: enclosing walls, optionally—one or more microphones, a signal processing device, at least one audio transducer, and an acoustic waveguide. The acoustic layer adjoins one or more internal areas of a laptop-type device. The signal processing device receives an internal signal from a laptop-type device. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: A soundskin for a pad-type device comprises a housing, at least one microphone, a signal processing device, at least one audio transducer, and an acoustic waveguide. The housing receives a pad-type device. The signal processing device receives a signal from a pad-type device when the pad-type device is received by the housing. The signal processing device provides a directive sound enhancement of the audio input signals based on room acoustics, such as reverberation, echo, noise, delay, frequency response, and/or speaker-positional information that is determined by the signal processing device. The audio transducer device generates an audible audio output in response to an audio signal output from the signal processing device. The acoustic waveguide receives the audible audio output and generates an enhanced bass audio output from the acoustic waveguide.

Abstract: A circuit architecture, or topology, that provides a level shifter substantially independent of the duty cycle of an input signal includes an H-bridge arrangement of field effect transistors, a pair of capacitively coupled input terminals connected to the gates of the high-side transistors and circuitry to set the bias voltage at the gates of the high-side transistors, wherein the bias voltage generation circuitry receives at least information indicative of both the H-bridge power supply voltage and the modulation of the input signal. Various embodiments include a switchable element coupled in series with a voltage divider portion in the bias voltage generation circuitry. The ratio of on to off time of the switchable element determines the average current through the voltage divider and thus the bias voltage. To prevent excessive short-circuit current flow through the high-side transistors, the switchable elements are turned off responsive to detection of a short-circuit condition.

Abstract: A differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the PSRR of the amplifier. In another aspect of the present invention, a differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the CMRR of the amplifier. In a further aspect of the present invention, a Class D amplifier is provided with a passive differential feedback, summing with an input current at a differential virtual ground produced by an amplifier which is a sub-section of the Class D amplifier.

Abstract: A circuit architecture, or topology, that provides a level shifter substantially independent of the duty cycle of an input signal includes an H-bridge arrangement of field effect transistors, a pair of capacitively coupled input terminals connected to the gates of the high-side transistors and circuitry to set the bias voltage at the gates of the high-side transistors, wherein the bias voltage generation circuitry receives at least information indicative of both the H-bridge power supply voltage and the modulation of the input signal. Various embodiments include a switchable element coupled in series with a voltage divider portion in the bias voltage generation circuitry. The ratio of on to off time of the switchable element determines the average current through the voltage divider and thus the bias voltage. To prevent excessive short-circuit current flow through the high-side transistors, the switchable elements are turned off responsive to detection of a short-circuit condition.

Abstract: A differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the PSRR of the amplifier. In another aspect of the present invention, a differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the CMRR of the amplifier. In a further aspect of the present invention, a Class D amplifier is provided with a passive differential feedback, summing with an input current at a differential virtual ground produced by an amplifier which is a sub-section of the Class D amplifier.

Abstract: A circuit architecture, or topology, that provides a level shifter which is substantially independent of the duty cycle of an input signal includes an H-bridge arrangement of field effect transistors, a pair of capacitively coupled inputs terminals connected to the gates of the high-side (i.e., connected to the positive power supply) transistors and a pair of voltage dividers to set the bias voltage at the gates of the high-side transistors, wherein one side of each voltage divider is coupled to the power supply node and the other side of each voltage divider is cross-coupled to the output node of the opposite side of the H- bridge.

Abstract: A laser diode is employed to output light. A laser driver is employed to drive the laser diode. A laser driver control unit is employed to control the driving, such that carrier concentration of the laser is substantially forced to a desired concentration as photon level of the laser initially arrives at a desired level. In one embodiment, the laser driver outputs a drive pulse to drive the laser diode, with the drive pulse having a complex waveform. In one embodiment, the complex waveform includes different transition time periods, and transient rates to raise the drive pulse from an initial level to a peak level. In another embodiment, the complex waveform includes different transition time periods and transient rates to raise the drive pulse from an initial level to a transition peak level and then drop the drive pulse back to an intermediate low level and then finally transition to a final peak level.

Abstract: A laser diode is employed to output light. A laser driver is employed to drive the laser diode. A laser driver control unit is employed to control the driving, such that carrier concentration of the laser is substantially forced to a desired concentration as photon level of the laser initially arrives at a desired level. In one embodiment, the laser driver outputs a drive pulse to drive the laser diode, with the drive pulse having a complex waveform. In one embodiment, the complex waveform includes different transition time periods, and transient rates to raise the drive pulse from an initial level to a peak level. In another embodiment, the complex waveform includes different transition time periods and transient rates to raise the drive pulse from an initial level to a transition peak level and then drop the drive pulse back to an intermediate low level and then finally transition to a final peak level.

Abstract: Non-looped continuous sound made up of random sequencing of digital sound segments is generated by taking several short segments of an otherwise continuous sound and forming independent records of those short segments. The stored segments are re-assembled into a sound sequence of arbitrary length based on selecting the next sound segment according to some statistical algorithm. The selected algorithm may be simply a random or pseudo-random selection, or it may provide a probability weighting to emphasize some sound records over others, or some combination of factors also affected by external stimuli such as light, heat or operator input. Apparatus for generating random sequenced digital sound are disclosed. Another aspect of the invention is logical sequence sound in which the selection of sound segments proceeds according to a logical sequence which is programmable.

Abstract: An electronic control system for model railroads incorporates a motor control unit, an electronic state generator that generates particular operating state signals responsive to multiple reset conditions. A first reset condition initiates sequencing of motor control states and a second super reset condition independently controls system initialization conditions increasing the overall number and accessibility of controller generated operating states.

Abstract: Electronic circuits and methods are disclosed for remote control of a locomotive in a model railroad layout having an interruptible DC power supply coupled to the railroad track. The locomotive motor is isolated from the track so as to allow use of polarity reversals on the track power signal for controlling remote effects in the locomotive such as sound and visual effects. An on-board electronic state generator is provided in the locomotive for maintaining one at a time of a predetermined set of states, at least one of the states having a corresponding remote effect associated therewith. Remote control signals such as a pulsed reversal in polarity of the DC track power signal (PRP) or high voltage pulse (HVP) are used to clock the state generator to a desired state, thereby permitting control of a plurality of remote effects using only the traditional DC power supply interface.

Abstract: Several short segments of an otherwise continuous sound are recorded and stored in a digital memory. The stored segments are concatenated together to form a sound sequence of arbitrary length, based on selecting the next sound segment according to some statistical algorithm. The selected algorithm may be simply a random or pseudo-random selection, or it may provide a probability weighting to emphasize some sound records over others, or some combination of factors also affected by external stimuli such as light, heat or operator input. Apparatus for generating random sequenced digital sound are disclosed. Another aspect of the invention is logical sequence sound in which the selection of sound segments proceeds according to a logical sequence which is programmable.

Abstract: Apparatus and methods are disclosed for transmitting very fast digital DC signals over the track for remote control in a model railroad layout, by selecting positive and negative lobes from the applied AC track power signal. This method allows digital transmission at 120 Hz rate that can be used within a 60 Hz AC system. This is fast enough to be used for Digital Command Control (DCC) and also capable of delivering large power output efficiently without the expense of filtering or exotic electronic control circuits. This method also has low sensitivity to electrical noise and does not generate significant noise during operation. We describe methods of transmitting and receiving positive and negative lobes and methods to extend this technology. We also describe other areas where this technology can be applied such as remote control of appliances connected to any AC power environment such as home or industrial electric power systems.

Abstract: Non-looped continuous sound made up of random sequencing of digital sound segments is generated by taking several short segments of an otherwise continuous sound and forming independent records of those short segments. The stored segments are re-assembled into a sound sequence of arbitrary length based on selecting the next sound segment according to some statistical algorithm. The selected algorithm may be simply a random or pseudo-random selection, or it may provide a probability weighting to emphasize some sound records over others, or some combination of factors also affected by external stimuli such as light, heat or operator input. The selection of sound segments proceeds according to a logical sequence which is programmable. Sounds are organized into groups of similar sounds which may be accessed according to subsects. Groups may include beginning (head), middle and end (tail) sound segments.

Abstract: A method and apparatus for directing the movement of a train around a model railroad track having one or more turn-outs activated by at least two separate arming signals. Each signal is linked to a specified direction of the turn-outs such as straight, curve right, or curve left. The arming signal is sent to all turn-outs on the railroad track but only the turn-out which the train is approaching is toggled to a position corresponding to the arming signal. All turn-outs over which the train is moving at the time the arming signal is sent are disarmed to prevent the train from derailing due to the toggling turn-out. Proximity-selection switches may also be used for slot-car operation or for city or highway vehicles which are part of a model or miniature diorama within the model railroad layout.