Abstract: An article of jewelry arranged to simulate natural optical effects, such as sparkle and scintillation, is described. The article comprises a jewel, such as a brilliant cut diamond and one or more light sources, such as colored LEDs, incorporated in the article of jewelry for emitting light so as to illuminate the jewel. The article also comprises a microcontroller for driving the one or more LEDs to cause them to emit light pulses of varying intensity thereby simulating said natural optical effects of the jewel. The duration of the light pulses and the location of each light pulse can be varied to enhance the artificial illumination. The article preferably has a cordless rechargeable power supply which avoids the need for unsightly electrical contacts by using an inductive loop charging circuit.

Abstract: An assignment system adapted to accommodate video and audio signals is provided with a digital cross-point switching matrix which is controlled by a control device which enables connections between selected inputs and outputs of said matrix. The input signals are first applied to analog-to-digital converters, from which the signal is converted into serial form before entering the cross-point matrix. The output from the matrix is converted to parallel form and thereafter to an analog signal by digital-to-analog converters. At any one input the color burst information contained on the incoming video signal, is detected and this controls the rate of conversion of the signal into digital form. The horizontal synchronizing pulse information is detected from the incoming signal and is added to the serial data stream in a coded form and after switching of the data is detected and retrieved before reconversion of the data into analogue form.

Abstract: An analogue-to-digital converter comprising a plurality of stages in series, each stage including a full wave rectifier with two inputs and two outputs. Each of the inputs receives an analogue signal together with a constant current such that the full wave rectifier current reverses direction when the analogue signal reaches a predetermined level. Temperature compensation means are provided comprising voltage generators connected to the rectifier to provide a voltage bias thereto so as to enable the point of reversal of the rectifier current to remain constant over a wide range of ambient temperatures. The voltage generators have a temperature coefficient of voltage corresponding in magnitude and acting in the same sense as the bridge rectifier.

Abstract: The television digital time base corrector for television equipment comprises an analogue to digital converter for receiving a video analogue signal, a store for receiving the successive line information in digital form from the output of the analogue to digital converter, a digital to analogue converter for receiving the stored signal, a read/write control circuit for writing the digital information into the store, an input oscillator for determining the rate of conversion of the analogue signal and the rate of writing into the store and output oscillator for controlling the rate of reading out of the digital information from the store and the rate of conversion of the digital information in the store. The input oscillator is in the form of a triggered oscillator which is switched on and off in time relationship with the video sync pulse and/or sub-carrier color burst, the period of switching on and off and the frequency of the oscillator being dependent upon the duration of the lines.