China
Africa
Explore chapters and articles related to this topic
Solid-State Amplifiers
Published in Jerry C. Whitaker, The RF Transmission Systems Handbook, 2017
At high-power levels not practical for Class A, the Class B amplifier is used. Class B is more power efficient than Class A and unlike Class A, a transistor (or other amplifying device) conducts for precisely half of the drive cycle of π radians. It is biased precisely at collector current cutoff. As stated previously, the class of operation has nothing to do with the device type, but rather its bias condition and its conduction angle. Since Class B operation means that the device is only conducting half of the time, a single ended amplifier may only be used at narrow bandwidths where the tuned output network provides the missing half-cycle by storing the energy presented to it by the active half-cycle, then returning it to the circuit when the device is off. For untuned applications, such as audio amplifiers and wideband RF amplifiers, a push-pull pair of devices operate during their respective half-cycles causing the amplifier to be active all of the time. In this situation, the point on the loadline halfway between the ends is at zero supply current for both devices and driven away from zero with drive. Figure 11.10 shows a graphical presentation of the Class B push-pull configuration.
Spatial Orientation and Disorientation
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
The neural signal from the semicircular canals represents the angular velocity of the head in the plane of each canal. At rest, a rate of firing of about 80 spikes per second can be measured in vestibular afferent nerves. A rotation in one direction results in an increase in the rate of firing proportional to the instantaneous angular velocity, and in the opposite direction, a decrease. Comparison of the signals from corresponding canals in each inner ear shows that, in the presence of a rotational stimulus, when one canal generates an increase in the rate of firing, the opposite canal will register a decrease. This so-called push–pull arrangement is familiar to electronic engineers and is used, for example, in the output of an amplifier to improve the linearity of the response and thereby reduce distortion. It appears that physiology is doing the same.
Electronic Circuits in Action
Published in Trevor Linsley, Electronic Servicing and Repairs, 2014
When an amplifier is used to amplify the input voltage or current in such a way that the output is an enlarged copy of the input and is not distorted, it is said to be a small signal amplifier. When an amplifier is used to amplify the power of an input signal it is said to be a power amplifier.Figure 5.26 shows the circuit diagram of an audio frequency amplifier. The left-hand side of the circuit, the op amp, is a small signal voltage amplifier which is used to amplify a small signal from, for example, the ear piece jack plug of a tape recorder. The right-hand side of the circuit is the power amplifier which is required to drive the speaker. This is made from a pair of complementary power transistors, one is an n-p-n and the other a p-n-p transistor which have beenmatched so that they have the same gain and other properties. When the voltage on the top transistor is positive the voltage on the bottom transistor is negative and vice versa. The amplification of each half of the voltage waveform is, therefore, shared between the two transistors. A circuit which is constructed in this way is known as a push-pull amplifier. The additional power required to drive the speaker in this circuit comes from the 9 V batteries.
Controlling the Speed of renewable-sourced DC drives with a series compensated DC to DC converter and sliding mode controller
Published in Automatika, 2023
K. Gurumoorthy, Sujatha Balaraman
The proposed work uses a set of SCBBCs and a push pull converter. The push pull converter is advantageous because the power electronic switches are in the low voltage side with reduced voltage stress and losses incurred in the switches. The SCBBC offers more power conversion efficiency because it is only a part of the output power that flows through the converter and the remaining part flows direct to the load. The same application can be realized using boost converters. But the voltage gain of the boost converter is low in the stable low-duty cycle region. The proposed method gives a large overall voltage gain, achieved by the push pull converter, even for a small duty cycle. The voltage gain is determined by the turn’s ratio of the push pull transformer. The proposed system works more stable and its power conversion efficiency can be compared with the generic converter and the super lift Luo converter as shown in Table 5. As compared to the efficiency of the super lift Luo converter which is around 82%, the proposed system offers an overall efficiency of 87%.
Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation
Published in Journal of Nuclear Science and Technology, 2022
Kazami Yamamoto, Michikazu Kinsho, Naoki Hayashi, Pranab Kumar Saha, Fumihiko Tamura, Masanobu Yamamoto, Norio Tani, Tomohiro Takayanagi, Junichiro Kamiya, Yoshihiro Shobuda, Masahiro Yoshimoto, Hiroyuki Harada, Hiroki Takahashi, Yasuhiro Watanabe, Kota Okabe, Masahiro Nomura, Taihei Shimada, Takamitsu Nakanoya, Ayato Ono, Katsuhiro Moriya, Yoshio Yamazaki, Kazuaki Suganuma, Kosuke Fujirai, Nobuhiro Kikuzawa, Shin-Ichiro Meigo, Motoki Ooi, Shuichiro Hatakeyama, Tomohito Togashi, Kaoru Wada, Hideaki Hotchi, Masahito Yoshii, Chihiro Ohmori, Takeshi Toyama, Kenichirou Satou, Yoshiro Irie, Tomoaki Ueno, Koki Horino, Toru Yanagibashi, Riuji Saeki, Atsushi Sato, Osamu Takeda, Masato Kawase, Takahiro Suzuki, Kazuhiko Watanabe, Tatsuya Ishiyama, Shinpei Fukuta, Yuki Sawabe, Yuichi Ito, Yuko Kato, Kazuo Hasegawa, Hiromitsu Suzuki, Fumiaki Noda
To achieve an acceleration from 400 MeV to 3 GeV in 20 ms, an acceleration voltage exceeding 440 kV per turn is necessary for the RF system. The revolution frequency of the RCS changes from 0.61 to 0.84 MHz; thus, the RF system needs to follow this frequency change. In fact, because the harmonic number of RCS is two, the fundamental frequency of the RF is twice the revolution frequency. Therefore, there are two RF buckets in the RCS, and two bunches are simultaneously accelerated. The RF system also has another function to manipulate the longitudinal density of the beam (namely, longitudinal painting [27,28]); furthermore, the RF of the second harmonics needs to be excited to make the RF bucket flatten. The higher harmonics RF helps reduce the density of the beam and the transverse space charge effect. To satisfy these requirements, we did not implement the conventional ferrite core cavity but the magnetic alloy (MA)-loaded cavity [29,30]. The core is made by winding the metallic ribbon of MA [31]. To change the radius of the winding core, we can make a large core that can fit to the large beam aperture of the RCS. The characteristics of MA core are a high saturation magnetic flux density (Bs > 1.3 T) and a high Curie temperature (>500°C). Furthermore, the MA material has a high permeability and a low Q-value, and these features enable the simultaneous excitation of the second harmonic RF in one cavity. Twelve RF cavities in total are installed in the tunnel, whereas an accelerating electric field is excited by applying an RF power fed using the tetrode vacuum tubes in the final amplifier close to the cavity. The amplifier comprises a push–pull circuit with two vacuum tubes. Each vacuum tube excites the upstream and downstream of the acceleration gap in different phases. Figure 7 shows the schematic and photograph of the RF cavity.