Some Scanners, Overlap Relays, Isolation Switches and Cut-outs White City London

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Time Division Multiplexers before electronics

This page contains a photograph which is one of several belonging to the photo gallery pages which are part of several pages relating to the invention of the world's first automatic totalizator in 1913 and Automatic Totalisators, the company founded to develop, manufacture and export these systems.

This is a close up image of part of the Julius Tote Scanners, Relay panels and Switchboard and is part of one of the first Large Scale Real Time Multi User Systems. The writing on the back of the photo reads White City London - but typical of any tote Distributor and Relay Board in English Julius Totes. Scanners or Distributors are synonymous names attributed to the circular devices at the bottom of the racks with an inner unbroken ring and a studded concentric outer ring and arms radiating from the centre. In operation the arms rotate, electrically connecting the unbroken ring to the studs in sequence. These devices are time division multiplexers long before the invention of digital electronics that made this a common concept. These devices send enabling pulses to the Ticket Issuing Machines which are attached to the studs and if the selected TIM has a transaction pending a transaction cycle begins recording the transaction and printing a ticket. Each scanner is connected to a single solenoid in a particular adder selected by the TIM. The adders are visible in the first and second photographs in the White City section of the Photo Gallery. As there are eight studs on each scanner, with a TIM attached to each one, eight TIMS are scanned by each scanner. Hence each solenoid in the adder causes the transactions from a group of eight machines to be summed by the solenoid's associated escapement wheel.

Above the scanners are overlap relays which hold the transaction cycle voltage from the scanner until the end of the transaction cycle after the arm has passed the stud. Above the relays are isolation switches used to disconnect a faulty ticket issuing machine from its associated scanner. In the top row are the Cut-out Relays mentioned below. There is a close up view of one of these Cut-out Relays, which today would be called a circuit breaker, in the following image in the Photo Gallery.

There is some technical text on the back of this photograph. I have included it here for the technically minded. The first sentence does not read well however I have copied it verbatim:
Cut out Relays wired in distributor common so that any excess amperage due to overlapping of bets from TIMs or faulty circuit breaker in any TIM in the group. Cut out relay is set to trip at just under 2A usually 1.85A. Thus if any TIM maintains its betting circuit unduly the plunger of cut out has time to rise and open its own circuit. If two issuers, by a wiring error, were on one TIM relay and betted simultaneously the cut out would instantly come out owing to the excessive amperage thus revealing the fault at once.

There is no photographers stamp on this print.