Ferranti Plc

501 Ferranti Limited

Robert M Murray

Brian E Pitches

Ian A Greig

Douglas J Rogers

Capacitance measuring apparatus comprises a variable capacitor VC and a reference capacitor FC. Circuits D, ID, are provided for generating a periodic waveform for application directly to the variable capacitor, and in inverted form to the reference capacitor. Switches means SM are operated by control logic CL to connect the two capacitors in sequence to the input of an integrating amplifier IA, the output of which is applied to a comparator CM to which is also applied a reference level. The output of the comparator controls the control logic. Output of the control logic is converted to an indication of the capacitance of the variable capacitor relative to that of the reference capacitor.

Capacitance measuring apparatus

Apparatus for dispensing a preset monetary amount of product, such as fuel, sold by volume and for use with a dispenser which calculates and displays a continuously increasing cost of the delivery has a number of selector buttons which relate to units of cost and which when selected set an appropriate number into a counter. The counter is coupled to the display, and the count is decremented by one for each unit cost of product actually delivered. During delivery of the first unit a store calculates the difference between a unit cost and the cost of a small predetermined volume, which volume is required to be delivered slowly to end the delivery and avoid under- or over-delivery due to mechanical or fluid inertia of the dispenser. When the counter indicates the final unit preselected is being delivered, a comparator compares continuously the cost displayed for that unit and the stored difference and when they are equal the delivery rate is slowed for the final predetermined volume. The apparatus may be used with pre-stored values where delivery is by volume rather than cost.

Dispensing preset amounts of a product

A unit price setting arrangement for differently priced products available from a remotely located dispenser for example, grades of fuel, from a pump, consists of a central transmitter and a receiver in each dispenser. The transmitter forms a series of fixed length binary words, one for each product, and transmits them in sequence repetitively. Each receiver counts words of the sequence received and compares them with the position of a selected product in the sequence to determine which word relates to the product of interest. That word only is used and is applied to a comparator with a corresponding word stored from a previous transmission to detect a change in the word. A shift register having a stored bit responds to an unsuccessful comparison to shift the bit through one location and a shift through a predetermined number of locations by successive unsuccessful comparisons, if the change is permanent, causes a controller to replace the stored value with the newly received one. The shift register is reset by a correct comparison if the change indicated by the comparison is not sustained and the stored value is unaltered. Thus any disturbance giving rise to a wrong binary word is ineffective but a deliberate change repeated over several transmissions is effective.

Price display setting arrangements

Liquid dispensing apparatus for dispensing a blend of first and second liquids has flowmeters operable to measure the quantity of each liquid delivered. The flowmeter outputs are multiplied by a factor equal to the proportion of one liquid in the blend and used to control a stepping motor which operates a blending valve. An error correction circuit is provided to correct for any accumulated error, and the apparatus also includes a cost determining circuit.

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Edinburgh, United Kingdom

Robert M Murray