923,571. Impulse transmitters. McGRAWEDISON CO. Sept. 16, 1960, No. 31925/60. Class 40 (4). [Also in Groups XXIV and XXXVIII] In an automatic dialling machine which records telephone numbers and produces impulse trains corresponding thereto, a continuous signal is recorded on a recording medium corresponding in length to the particular digit dialled, i.e. the digit " 1 " is recorded as a 40 milliseconds (msecs.) signal and all other digits are recorded as [40+(n-1)100] msecs. signals, where n is the particular digit dialled, e.g. digit "6" corresponds to 540 msecs. During playback the signals are converted into impulses corresponding in number to the original digit dialled in order to operate automatic exchange equipment. By these means a plurality of different telephone codes can be set up on the machine and thereafter any one of the codes can be sent to line by the operation of a single button. A detailed description, of the mechanical linkages between various control knobs and their respective switches and of the gearing between a constant speed motor and the parts of the apparatus driven thereby, is given with reference to Figs. 1-38 (some not shown) and also a second embodiment, Figs. 40-44 (some not shown) is described. General description of machine (Fig. 1).-an order to record a telephone code, knob 25 is rotated until an index line 34 on a paper tape 8 is brought into coincidence with the part of the alphabetical scale 33 corresponding to the name of the person whose code is to be recorded. A glass slide 32a is removed and the name and code are written on the tape 8. Record button 65 is pressed to release a dial lock, to energize a recording head 121, to drive the latter forward acting initially as an eraser for about 500 msecs., to lock tape 8 and a recording tape 35, and to mute the line circuit L 1 , L 2 (Fig. 39). The recording tape 35 is driven by control knob 25 concurrently with tape 8. The telephone code is then dialled in the normal way using dial 199, return of the dial being under control of motor 144. If it is desired to dial a long. distance number an access button 314, revealed on operation of record button 65, is operated so as to provide a predetermined interval between the first digits of the code and the later digits which are necessary for completing the call once the distant exchange has been reached. Upon completion of dialling, reset button 66 is operated to drive the head 121 forward for another 500 msecs., again acting as an eraser, and then to return it to its home position. In order to call a number set up, by control knob 25, in the display slot 32, playback bar 64 is depressed, whereupon head 121 now acting as a playback head traverses the tape and in response to the length of signal picked up thereby operates a solenoid which in turn operates the dial impulse contacts. Dial assembly (Fig. 21).-This is supported by a frame 211 connected to the base 2 of the recording machine and consists of a finger plate 199 mounted on a shaft 204 supported by bearings in mounting plates 260 and 208. A motor gear 214, rigidly connected to the shaft, drives an oscillator gear 223 through a lostmotion coupling, the latter gear being frictionally coupled through a one-way spring clutch 240a to a shaft 229 geared to motor 144. Return of the dial to its home position is governed by the motor acting, through spring clutch 240a and oscillator gear 223, against the dial return spring 219 attached to shaft 204 and shaft housing 217. A dog 234 is retained by the operating arm 236a of a solenoid 236 except during playback when it is released and by means of a further spring clutch 235 drives a cam 232 to operate the impulsing springs 237. The dial lock consists of an armature 252 normally engageable with a recess 254 in motor gear 214, armature 252 being movable by a dial lock solenoid 251. Operation of impulse transmitter (Fig. 36).- On winding up the dial a pin 222, attached to motor gear 223, initially takes up a lost-motion period provided by slot 224 in oscillator gear 214, both gears then being rotated together until the finger in the dial reaches the finger stop. Both gears are provided through about half their thickness with long peripheral slots, thereby giving them ten spaced teeth 256 and 257. When the oscillator gear starts to rotate (clockwise, Fig. 36) a latching pawl 269 is released and as each of the teeth 257 strikes a lobe 266a on a two-lobe (spring urged) cam 266, the latter is kicked anticlockwise; this has no effect since operating arm 265 for oscillator switch 259 is resting on a smooth portion of cam 266. However, during the return motion, the first tooth 257 causes cam 266 to rotate clockwise so that pawl 269 engages lobe 266b and the latter moves arm 265 so as to operate the switch. Towards the end of the return motion a finger 271 on gear 223 releases the pawl 269 and hence switches off the oscillator which has been connected to the recording head in order to record a signal corresponding to the digit dialled. Motor switch 258 is controlled in a similar way but when this is switched off by finger 279, the motor is not stopped immediately but is controlled through an alternative circuit (to be described). Oscillator switch 259 and motor switch 258 are mounted on mounting plates 260 and 208 respectively (Fig. 21) and the stud 218 (Fig. 36) serves as a stop for the pin 222. Recording (Fig. 39).-Record button 65 is depressed and via its contacts 1, 2 energizes a record relay 315 and an auxiliary record relay 316 in addition to its mechanical functions outlined above, and over its contacts 4, 5 it energizes the dial lock solenoid 251 from the combined power supply and oscillator unit 318. Operation of relay 316 connects a 400 cycle erase signal to recording head 120 from terminal 322 of unit 318 and the oscillator dial switch 259; isolates the head from playback amplifier 323 and also energizes a clutch solenoid 181 (Fig. 3, not shown). The latter is effective in engaging the drive from the motor 144 to the carriage (for the recording head) advance mechanism and in lowering the head on to the recording tape. Record relay 315 at contacts 6 and 7 closes a circuit for motor 144, the latter driving the head forward for 500 msecs., when a jog switch 195 is released by the head carriage and thus stops the motor. Mute switch 194, also operated by the head carriage, is closed as the jog switch opens, and serves as an additional safeguard for keeping the dial solenoid 236 and hence impulsing contacts 237 quiescent. At this time, the transmitterreceiver TR circuit is not short circuited so that normal calls can proceed, however impulse contacts 237 are short circuited. Upon dialling the first digit, release of the finger plate causes motor switch 258 to operate (Fig. 36) within 10 msecs., with consequent operation of motor relay 321. The latter locks up, restarts motor 144 and hence the carriage is again driven forward, and releases dial lock solenoid 251 so that when the dial reaches its home position it will be temporarily retained there. 60 msecs. after operation of motor switch 258-the motor having reached normal speed-oscillator switch 259 is operated and thereby connects a 200 c/s. signal from terminal 325 of unit 318 to the recording head 120. After 40+(n-1)100 msecs., oscillator switch 259 is switched "off" and although 50 msecs. previously motor switch 258 was released the motor still continues to run since motor relay 321 is locked up. How. ever, an advance clutch solenoid 280 is now energized, and is effective in engaging the drive from the motor to a cam which on rotation can operate four cyclically placed switches 310-313 (Fig. 18, not shown). 550 msec. after the motor switch 258 was switched off, the cam operates a first interdigital switch 310 and this causes relay 321 to drop out and so de-energize the motor, the cam being spring-urged returning to its home position. There is thus provided a 500 msecs. blank space on the recording tape between any two digits. Release of motor relay 321 causes the re-energization of the dial lock solenoid so that the next digit can be recorded in the same manner. Access relay operation.-As indicated above, the access button 314 is pressed, if a long distance call is to be made, after the routing digits have been sent. In so doing, switch 334 is operated to lock-up access relay 320. The latter starts the motor, thus causing the recording head carriage to be driven forward in the erasing condition, the advance clutch solenoid being also energized to start its cam revolving. In this ease interdigital switch 310 when operated has no effect, but 1450 msecs. after commencement a second interdigital switch 311 operates to out out the motor relay and hence the motor and also the access relay itself. If the access switch is held on manually for longer than 1450 msecs., the advance clutch remains engaged but since switch 311 is open the motor is stopped and cannot be restarted until switch 334 has been released. Reset operation.-Upon pressing reset button 66, reset switch 119 is latched on by the same latching means that is retaining the record switch 97. In this case motor relay 321, motor 144 and advance clutch solenoid 280 are energized but the revolving cam of the clutch now only operates a reset advance switch 313 after 2500 msecs. from commencement of rotation. Switch 313 causes a carriage return solenoid 174 to operate. This disengages the drive to the carriage causing it to return to its home position and also unlatches the record and reset buttons. Playback.-Depression of playback bar 64 causes playback switch 83 to operate, and the tapes to be locked in position, the dial lock also being operative. Motor relay 321 is energized and since the carriage is in its home position, i.e. clutch switch 189 operated, clutch solenoid 181 operates. Since the motor is running, solenoid 181 engages the drive to the car