Abstract: The disclosed circuit provides a signal generator which is particularly adapted for use as an audible "kilo-sonic" game device in which a plurality of switches are provided so that the different combinations of switch positions produce a corresponding number of different sounds. The circuit includes a voltage-controlled-oscillator (VCO) having an output coupled to a transducer such as a speaker. The VCO is modulated in accordance with a control signal, provided by an up-down staircase generator which is responsive to a pulse generator, to vary the frequency of its output signal. The output of the pulse generator is also selectively coupled with the output of the staircase generator.

Abstract: A dynamic expander which is particularly suitable for restoring the original dynamic range of prerecorded stereo sound program material is disclosed. In this embodiment, the expander comprises first and second variable gain amplifiers respectively coupled to a stereo input. The gain of the amplifiers is controlled by a common slow-attack, slow-decay time-constant circuit. An input of the time-constant circuit is coupled to the stereo input and the time-constant circuit responds thereto to provide a control signal which is indicative of the volume of the program material but which varies in accordance with the characteristics of a non-linear element in the time-constant circuit and with the slow-attack and slow-decay characteristics of the time-constant circuit. The control signal of the time-constant circuit drives a light-emitting-diode (LED) which, in turn, determines the resistance of a pair of matched, light-controlled-resistors (LCR's).

Abstract: The disclosed circuit provides a wideband, wide-range logarithmic responding voltmeter particularly suitable for use as a transducer analyzer. The circuit includes an input for receiving a given A.C. input signal which can vary within a 100 db dynamic range. The input signal is coupled to a buffer amplifier the output of which is capacitively coupled to a logarithmic converter. The converter includes an operational amplifier and provides an A.C. output signal which is proportional to the logarithm of its A.C. input signal. The open loop gain of the operational amplifier is utilized to provide the A.C. output signal. The output signal of the converter is capacitively coupled to a precision AC/DC converter which rectifies and filters the output signal to provide a D.C. output voltage the level of which is, therefore, also proportional to the logarithm of the given A.C. input signal within its 100 db range. The D.C.