Abstract: There is disclosed a fireplace system to be installed in a chimney, the chimney having at least two openings in side walls of the chimney, comprising a hearth vertically moveable in the chimney, the hearth being accessible through the openings, doors to seal the openings, lifting means connected to the hearth for moving the hearth vertically in the chimney, vertical guide means for guiding the hearth in the chimney during vertical motion, and holding means for holding the hearth at a vertical position.

Abstract: A selective efficiency (threshold) video frequency nonlinearity precorrection device comprising a direct channel (wide band channel) and an auxiliary processing channel (selected frequency correction channel), are both coupled to an input receiving the video frequency signal. The auxiliary channel may comprise a low pass filter, an inverting amplifier, a nonlinearity corrector circuit selecting a range of the signal limited by thresholds added with suitable phase and amplitude to the signal transmitted by the direct channel so that the resulting signal has, with respect to the input video frequency signal, compression or expansion limited to the range thus selected and only for the low frequency components of this signal.