. The Bell System technical journal . is equipped with a camera for the purpose ofphotographing a clock on the oscillogram to indicate the exact timeof occurrence of the disturbance recorded. Any other information itis desired to associate with the records made by a particular oscillo-graph may be recorded photographically along with the clock. Inseveral cases calendar clocks have been employed indicating the dayand the month, and indicating whether the time is or OSCILLOGRAPHS 371 A schematic diagram of the optical system of the recorder and of thecamera, as used in the polar oscill
. The Bell System technical journal . is equipped with a camera for the purpose ofphotographing a clock on the oscillogram to indicate the exact timeof occurrence of the disturbance recorded. Any other information itis desired to associate with the records made by a particular oscillo-graph may be recorded photographically along with the clock. Inseveral cases calendar clocks have been employed indicating the dayand the month, and indicating whether the time is or OSCILLOGRAPHS 371 A schematic diagram of the optical system of the recorder and of thecamera, as used in the polar oscillograph, is shown in Fig. 1. Some ofthe mechanism essential for operation is omitted for the sake ofclearness. One of the calendar clocks used in conjunction with these oscillo-graphs is shown with cover open in Fig. 2. A space is left below theclock face for a card on which may be written identifying or otherinformation relative to records that may be obtained. Lamps aremounted within the cover to illuminate the clock when OSCILLOGRAPHCIRCUIT Fig. 3—Circuit of high-speed line-relay. Both oscillographs are equipped with automatic devices whichenable them to make records of transients for which they are intendedwithout the attention of an operator. These automatic features willbe described in some detail in the following discussion of the individualoscillographs. One part, however, a high-speed line-relay is common to consists of a pair of high-speed polar relays, the windings of whichmay be connected into a line in such a way that, depending on thepolarity, one or the other will be operated by any pulse of sufficientmagnitude. The relays may be so biased that they operate only onpulses in excess of any given magnitude. They are connected so thatwhen they do operate they remain operated until reset by someexternal means. Contacts on the relays are connected to the apparatusto be controlled so that a single positive or negative pulse will put that 372 BELL SY
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
