Abstract: The present invention is a ceiling-mountable enclosure comprising a support frame, a lightweight inner enclosure, and a back box configured for installation in a suspended ceiling. The apparatus of the present invention includes a removable device door configured to be mounted to the support frame. Electrical and signal wires are routed through conduit access plates provided at the back box. Electrical or other equipment is mounted to a removable device door. The removable device door with mounted equipment is attached to the support frame, then rotated upwards to fit flush with the ceiling and fastened to the support frame. A variety of power receptacles are provided that are configured to be mounted to either the back box, the inner enclosure, or the removable device door. The enclosure includes a cooling system comprising an electrically powered fan and air ducts integrated into the inner enclosure.

Abstract: A simplified VCA circuit is presented. The VCA of the present invention uses fewer components and is less complex than prior art OTA-based VCAs. Further, the VCA of the present invention has improved total harmonic distortion (THD) and DC offset characteristics as compared to prior art VCAs. The VCA may be used to prevent clipping with the addition of clipping detection circuitry.

Abstract: A triangular waveform generator includes a square waveform clock circuit and an integrating circuit. The integration circuit receives input from the square waveform clock circuit and generates a triangular waveform output. A feedback circuit is operatively connected to the integrating circuit to reduce the audio band noise content in the triangular waveform output. The feedback circuit acts as a DC balance without significant sacrifice in the linearity of the triangular waveform output.