Patent GB-663574-A (GB)
Title: Improvements in or relating to electrical circuits employing static electrical switches
Inventor: ODELL ALEXANDER DOUGLAS
IPC: H04Q3/00
Filed: 1949-03-04
Abstract: 663,574. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. March 4. 1949, No. 5933/49. Class 40 (iv). [Also in Groups XL (b) and XL (c)] Impulse storage and regenerator equipment employs a chain of discharge tubes (see Group XL (c)) upon which the digits comprising a number are stored as a pattern formed of conducting tubes spaced apart by non-conducting tubes in accordance with the value of each digit. Stepping pulses applied in common to the cathodes of all the tubes cause the complete pattern to travel stage-bystage along the chain influencing the final tube to control the regeneration of impulses in accordance with the stored number. In Fig. 5 a five-digit number impulse train received on relay A is stored on a chain of 50 tubes G1-G50, the chain subsequently serving to control the regeneration of the impulses by magnet-springs L1 operating at controlled speed and make-and-break ratio. Tubes GA-GE function as a digit-counting chain. Relay A operates via the line loop and operates relay B over a1 up which prepares C over b up. Contact b2 up triggers tubes G1  and GA, and then relay A follows the separate impulses and over a2 applies voltage pulses across R7 to the cathodes of tubes G1-G50 which step the fired tube along the chain, one stage for each impulse. Relay C is slowreleasing and operates to the first and releases after the last impulse of each digit train. On releasing, contact c1 back triggers G1 again, and contact c2 back moves the digit-counting chain along one, triggering GB and extinguishing GA. This process is repeated for the other digits of the number, thus building up a pattern of conducting tubes spaced apart by non-conducting tubes in accordance with the value of each digit. On c2 falling back after the fifth tube is received, tube GF is triggered, operating relay D. Over dl up the control of the storage chain is transferred from a2 to magnet springs M2, and d2 up prepares relay IG for operation at the next " break " of magnet springs M1. Contact d3 up transfers control of the digit-counting chain from relay C. to relay E. Contact d4 triggers tube GA, resetting the counter. On the first break of springs Ml following operation of relay D, relay IG operates. Contact ig2 connects resistance R7 to springs M2 and the pattern on the storage chain then moves along stage-by-stage until the final tube G50 triggers, operating relay E. Contact c1 up triggers tubes GK and GJ, operating relays G and F. Relay G has a delay such that contact g2 prevents the digit-counting chain stepping at this first operation of relay E. Contacts f4 and f5 complete the circuit for tube GK which triggers after a delay determined by the charge rate of condenser c3. This delay constitutes the inter-digital pause. Contact f2 removes pulses from the storage chain, contact f3 shunts out the loop springs and contact f1 releases relay IG. At the end of the inter-digital pause the striking of tube GK extinguishes tube GH, so releasing relay F. This allows relay IG to operate again and impulses commence to be transmitted to line by springs L1. The impulse train is interrupted when tube G50 again becomes operated, so constituting the first transmitted digit. Operation of relay E causes the operation of relay F as before, starting the loop springs and initiating an inter-digital pause. At the end of the pause relay F releases and the transmission of the next digit. commences. The digit-counting chain is stepped once for each digit and at the end of the five digits tube GG is triggered from e1 via d6 up. Tube GG in operating de-ionizes tube GF, thereby releasing relay D which over dl back returns the control of the storage chain to contact a2 and so resets the circuit for a subsequent operation. In order to eliminate the delay which will arise when a pattern corresponding to a number with small valued digits is stepped along until tube G5a is fired, an impulsing arrangement with a higher repetition rate, such as a multi-vibrator, may first be connected to the storage chain and a relay employed in the anode of tube G48 or G49 to change over from the higher rate impulsing arrangement to the impulsing springs already described. The retransmission of a stored number may be delayed under the contiol of external circuits by inserting an extra make contact in the circuit of relay IG.