| 释义 |
push-pull, a., n., and adv.|pʊʃˈpʊl|
[f. push- + pull v. or n.2]
A. adj.
1. Characterized by, caused by, or being a forced reciprocating motion; responding to or exerting both pushes and pulls. Also transf. and fig.
push-pull train (see quot. 1966).
[1894Phil. Mag. XXXVIII. 301 They..show that the ‘push and pull’ theory is capable of giving an adequate account of the action of the telephone.] 1929Prof. Paper Inst. P.O. Electr. Engineers No. 124. 34 The frequency characteristics of a Western Electric..‘push-pull’ carbon transmitter [sc. a microphone]. 1934[see multipole a.]. 1940Chambers's Techn. Dict. 687/2 Push-pull microphone, a carbon microphone in which two carbon-granule cells are mounted on either side of a stretched diaphragm, so that amplitude distortion arising in one is largely balanced out by the opposite phase amplitude distortion in the other. 1951Engineering 10 Aug. 178/3 ‘Push-pull’ fatigue tests on welded bridge members were continued. 1959[see facia 2]. 1962R. B. Fuller Epic Poem on Industrialization 50 Basic structural stability..by segregated satisfaction of isolated articulating push-pull forces. 1963Times Rev. Industry June 117/1 Fork Truck Attachments... Drum forks, brick handling forks, push-pull device. 1966K. Möller Amer. & Brit. Railway English 31 Push-pull, reversible train..a type of locomotive-hauled suburban train fitted with driving control apparatus connected to the engine, at the rear end. 1971Engineering Apr. 110/2 (Advt.), A responsive industrial control system taking care of loads from a few ounces to over 1000 lb through push-pull cables. 1972Modern Railways Sept. 364 Instances continue to occur of Glasgow-Edinburgh push-pull trains being worked by single locomotives. 1972Science 20 Oct. 311/3 Cyclic AMP and cyclic GMP function in opposite directions, that is, in a push-pull fashion to exert long-term control over neuronal excitability in the sympathetic ganglion. 1978A. Huxley Illustr. Hist. Gardening iv. 119 The push-pull weeder hoe—with a flat oblong blade sharpened on both edges.
2. Electronics. Having or involving two matched valves or transistors that operate 180 degrees out of phase on identical alternating inputs, so that they conduct for alternate half-cycles and their combined output is the sum of each acting alone, making possible increased power without reduced efficiency.
1924Wireless World 4 June 277/2 With the push-pull amplifier one may employ smaller and therefore less expensive valves. 1925Motor 8 Dec. 980 B/1 The Push-pull Wireless Circuit. 1932Oxford Times 23 Sept. 22/5 Some manufacturers stock ‘pairs’ of carefully matched valves for push-pull amplification. 1945Electronic Engin. XVII. 431/2 A more satisfactory way of cancelling or reducing cathode self-bias distortion is to use push-pull stages with common self-bias. 1955Radio Times 22 Apr. 30/1 Table radiogram with 6-watt ‘push-pull’ output. 1965Wireless World July 329/2 Fig. 8 shows a push-pull 55 kc/s oscillator which provides erase and bias signals. 1970J. Shepherd et al. Higher Electr. Engin. (ed. 2) xxiv. 778 The fact that both p–n–p and n–p–n transistors are available enables push-pull circuits to be designed without transformers... If a p–n–p and an n–p–n transistor are fed from the same drive, a given input swing will cause one transistor to conduct more while the other conducts less, giving a push-pull operation. 1974Harvey & Bohlman Stereo F.M. Radio Handbk. v. 127 The driver transistor TR2 provides a common phase signal drive to the bases of the output pair but since they have complementary characteristics, the operation is in effect push-pull.
3. Cinemat. (See quot. 1973.)
1934Jrnl. Soc. Motion Picture Engin. July 52 In addition to its inherent freedom from ground noise, the push-pull sound track has other advantages. 1938Encycl. Brit. Bk. Year 498/1 Although not new in 1937, the use of push-pull sound recording increased considerably during the year. 1959B.S.I. News Sept. 25 Sound records and scanning area of 35 mm double width push-pull sound prints (normal and offset centreline types). 1973D. A. Spencer Focal Dict. Photogr. Technologies 498 Push-pull sound track, optical sound track on a cine film divided into two equal parts which were exposed to light modulated in opposite phase.
B. n. Chiefly Electronics. A push-pull arrangement or state; esp. in adv. phr. in push-pull.
1929Exper. Wireless & Wireless Engineer VI. 307/1 A pair of valves, (or banks of valves), working in opposite phase, commonly called ‘Push-pull’. 1932Oxford Times 23 Sept. 22/5 Push-pull gives the last stage a much greater power-handling capacity. 1943Electronic Engin. XVI. 55/1 The advantages to be gained by the use of push-pull for deflection are so great that unbalanced time-bases are rarely employed in cathode-ray tube circuits. 1948A. L. Albert Radio Fund. ix. 360 Radio-frequency power amplifiers often are operated in push-pull. 1962A. Nisbett Technique Sound Studio 276 Movement of the stylus produces variations in the magnetic flux, which in turn generates a current in a coil (or in two coils situated on paths which are favoured alternately, and operate in push-pull). 1962Listener 7 June 1006/2 One could not help speculating on the strange symbiosis or state of push-pull—call it what you like—which exists between him and his age. 1975G. J. King Audio Handbk. iv. 83 The output stages of hi-fi amplifiers employ two transistors in push-pull.
C. adv. Electronics. In a push-pull manner.
1947R. Lee Electronic Transformers & Circuits v. 109 Operation may sometimes be improved by the use of two tubes connected push-pull. 1978Nature 6 Apr. p. xxxiii/2 Errors existing between the DC reference and the detected signal are amplified and applied push-pull to a transverse field electro-optic light modulator. |