A Numerical Model for Water and Solute Movement in Forest Soils and its Application to Q" Transport in Microlysimeters

An electrical noise generation circuit for use in conjunction with an electro-acoustic transducer to simulate the sound of burning wood. A small loudspeaker enclosure accommodates a battery driven circuit in which a wideband electrical noise signal is produced by current flow through a zener diode. The noise signal is amplified by a frequency selective amplifier designed to have a high gain at a selected frequency in the audio frequency range, and rectified to produce unipolar signals which have randomly variable amplitudes and occur at random intervals. The unipolar signals are amplified by an amplifier having an adjustable input threshold bias. By adjustment of the bias level, output signals from the amplifier, and sounds produced by the loudspeaker, may be varied from intermittent individual pulses to rapid "bursts" of pulses. Operation of the circuit in proximity to an artificial log fire produces a surprisingly realistic audible simulation of wood burning sounds.