AUTODIAL No. 301
|See Autodial No. 302
Extract from an article on Repertory diallers in the POEEJ, Vol 62, page 188, October 1969.
This autodial is a self-contained unit with an internal mains-driven power unit, measures approximately 6 in x 4 in x 6 in and weighs 34 lb. In the top of the unit is a card chute through which the card falls during automatic dialling. The card is arrested at each row of punched out holes by a solenoid latch pin, until on completion of dialling the card drops out into a translucent tray. A storage compartment for thirty cards is provided behind the card chute. A call may be cancelled at any time during the dialling process by pressing the button which is situated in front of the card slot, and replacing the telephone handset.
The cards, which measure 3.5 in x 2.25 in, are moulded in A.B.S. Copolymer with 16 rows of potential holes, each hole covered with a thin web which can be removed as required with a suitable pointed instrument. Writing surfaces are provided along the top and down the left-hand side for the name and telephone number, respectively, of the called subscriber.
A typical card is shown to the right, each row of holes corresponds to one digit of the telephone number. The code is derived by deducting the number required from 16, and punching out holes corresponding to the result, where the first column on the left represents the value 1, the second column the value 2, the third column the value 4 and the fourth column the value 8. Therefore, for the digit 7,
code digit 9 must be recorded, i.e. holes punched out in column 1 and column 8. The digit 0 must be considered as 10, hence holes to the value 6 would be punched out. A jig is provided to assist the user in programming cards correctly.
The dial-pulse generator is clamped by the output from the i.d.p. generator. The termination of this output triggers a 5 ms timer which provides a setting potential for the
If a public-exchange access digit from a p.a.b.x. is required to precede a national or an international telephone number, the access digit is recorded in the normal manner using the first row of holes, but the fifth hole is also punched out. The detection of this fifth hole causes the following i.d.p. to be increased to two seconds. This allows time for public exchange dial tone to be connected before the remainder of the telephone number is transmitted.
Last revised: December 11, 2018