DOCSLIB.ORG

Application of Mixed Colloidal Magnetic Fluid of Single Domain Fe3o4 and Nife2o4 Ferrite Nanoparticles in Audio Speaker

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Application of Mixed Colloidal Magnetic Fluid of Single Domain Fe3o4 and Nife2o4 Ferrite Nanoparticles in Audio Speaker S. D. Kemkar et al. Int. Journal of Engineering Research and Application www.ijera.com ISSN : 2248-9622, Vol. 7, Issue 1, ( Part -3) January 2017, pp.11-18 RESEARCH ARTICLE OPEN ACCESS Application of mixed colloidal magnetic fluid of single domain Fe3O4 and NiFe2O4 ferrite nanoparticles in audio speaker S. D. Kemkar*, Milind Vaidya**, Dipak Pinjari***, Sammit Karekar****, Sanjana Kemkar*****, Siddhesh Nanaware******, Sanjukta Kemkar******* *Department of Physics, Smt. Chandibai Himathmal Mansukhani College, Ulhasnagar, India **Department of Physics, Vedanta College, Vithalwadi, India ***Department of Chemical Engineering, Institute of Chemical Technology, Mumbai, India ****Department of Chemical Engineering, Institute of Chemical Technology, Mumbai, India *****Smolensk State Medical University, Smolensk, Russia ******STES NBN Sinhgad School of Engineering, Pune, India *******Department of Microbiology, Smt. CHM College, Ulhasnagar, India ABSTRACT Ferrofluids are stable suspensions of colloidal ferrimagnetic particles in suitable non – magnetic carrier liquids. They have attracted a lot of attention from scientists and engineers due to their many interesting properties and applications in various branches of engineering. The present work reports the performance of colloidal fluid of single domain nanoparticles of NiFe2O4 and Fe3O4. The thermal properties and its dynamics on magnetization as well as its effect on thermal conductivity on the colloidal fluid are studied here. Advantages of the increased thermal conductivity and optimization of magnetization of mixed colloidal fluid is used to extract the heat from voice coil. Nanoparticles of 21 nm of Fe3O4 and 12 nm of NiFe2O4 are used for mixed colloidal fluid. The suspension of particles is achieved by coating the nanoparticles with mono-corboxylic group on both the types of particles. The higher size (21 nm of Fe3O4 and 12 nm of NiFe2O4) particles are taken for synthesizing colloidal fluid, to have magnetic property of mixed colloidal liquid at elevated temperature of voice coil of speaker (Higher sized particles gives better magnetization). Oil is used as a carrier. Mixed magnetic colloidal fluid is used as a medium for damping so that noise is reduced at higher temperature of voice coil. Keywords: Audio speaker, nanoparticles of NiFe2O4 and Fe3O4, magnetization, mixed colloidal magnetic fluid. I. INTRODUCTION studied [8]. Their work was on increasing the radial Nowadays, nanotechnology is emerging as restoring force on the voice coil and factors one of the prime fields of technology. influencing splash loss of the ferrofluid due to shock. Nanotechnology deals with creation of useful nano- Ferrohydrodynamic analysis was employed for materials and devices through control of these matters modeling. Ferrofluid is a temperature sensitive fluid, on nanometer scale. Such a material has different because they exhibit some properties like high phenomena and many physical properties that have thermal conductivity, small change in temperature, been observed on this scale. The phenomena and large change in magnetization. In case of mixed benefits of this technology are used in making colloidal ferrofluids, small change in temperature and materials in many fields like nano-electronics [18, 20, small change in magnetization occurs. This work 21, 22], optical fiber [1,17,19], computing, medicine deals with the preparation, characterization and and health, space exploration, environment and application of the mixed ferrofluid on audio speaker energy, aeronautics, magnetic recording media, for performance up gradation and optimizing the magnetic fluid, catalysis, medical diagnostics, magnetization of mixed colloidal fluid. We aim at pigment in paint and ceramics [2-4] etc. Nano- designing of colloidal magnetic fluid for consistent science and technology is emerging as a very performance on heat extraction, noise damping and promising field as far as applications are concerned. high fidelity achievement with minimum deviation in Various Devices based on ferrofluids continue to magnetization against temperature. The NiFe2O4 have offer high reliability and low cost solutions to many been used because of its high permeability in higher complicated industrial problems [5]. Many frequency range and low core losses at such applications based on the susceptibility of the frequencies, as well as somewhat flat magnetization ferrofluid are devised [6]. Various studies on the characteristics in the temperature span of interest. magnetization of the magnetic colloidal fluid have The heat generated by the voice coil will be been carried out [7]. Recently, extensive study on partly transferred to speaker components by the way audio speakers containing ferrofluid has also been of convection and conduction under the situation www.ijera.com DOI: 10.9790/9622-0701031118 11 | P a g e S. D. Kemkar et al. Int. Journal of Engineering Research and Application www.ijera.com ISSN : 2248-9622, Vol. 7, Issue 1, ( Part -3) January 2017, pp.11-18 when only air is present in the coil. This process is not so efficient. The pioneering work on application of ferrofluid in speaker was carried out with reference to centering of voice coil and enhancement in performance of voice coil with ferrofluid in the vicinity of the voice coil [9]. II. PREPARATION OF NiFe2O4 AND Fe3O4 NANOPARTICLES AND THEIR FERROFLUIDS The particles are prepared by chemical co- precipitation method and dispersed in the carrier liquid with stabilizer. The nanoparticles are prepared Figure 1(a). TEM image of NiFe2O4 ferrofluid sample. using aqueous solution of FeCl3 and NiCl2 with (2:1) proportion in ammonium hydroxide to achieve X-rays diffraction characterization has also NiFe2O4 magnetic nanoparticles. Ferritization of NiO been performed on the Nickel substituted particles. 0 and Fe2O3 was achieved at 98 C. Oleic acid XRD characterization was carried out by using molecules were adsorbed on particles. Particles were powder X-ray diffractometer (Phillips PW 1800, decanted and washed with acetone as well as warm range is 6-80O 2θ). Fig.1(b) shows that the particles water three times. Collected particles were dried in have inverse spinel structure of calculated size of oven and dispersed in transformer oil as carrier. Dried 12.3 nm. The details of plane d- spacing and 2 theta powder sample was preserved for XRD values are given in table 1. characterization. Ferrofluid was centrifuged at 4500 RPM for one and half hour. Lumps were removed and clean solution was obtained. The volume fraction Фm of 0.08 was prepared for NiFe2O4. Similarly, Fe3O4 magnetic nanoparticles were also prepared with chemical co-precipitation method. Aqueous solution of salts of FeCl2 and FeCl3 with 1:2 proportions in NaOH base solutions were used to achieve Fe3O4 magnetic nanoparticles. The ferritization was readily achieved at room temperature without any difficulty. Surfactant molecules of Oleic acid were adsorbed on particles. Particles were decanted and washed. Magnetite powder was dried in oven for 24Hrs at 80OC. Powder Figure 1(b). XRD pattern of NiFe2O4 powder. was dispersed in transformer oil. Samples were centrifuged at 4500 RPM for one and half hour. Table 1. d-spacing and 2theta values for NiFe2O4 crystal. Lumps were removed and clean ferrofluid was obtained. Dried sample was also preserved for XRD characterization. Ferrofluid with volume concentration of 0.08 was prepared. III. CHARACTERIZATION OF NiFe2O4 AND Fe3O4 NANOPARTICLES TEM of the sample of NiFe2O4 was obtained as in Fig 1(a). The morphology and particle size of this nanoparticle was characterized by transmission electron microscopy (TEM, H-7650 accelerating voltage of 120 KV).TEM shows the particle size of TEM of the sample of Fe3O4 was obtained as in Fig about 12 nm. 2(a). TEM shows the particle size of about 21 nm. www.ijera.com DOI: 10.9790/9622-0701031118 12 | P a g e S. D. Kemkar et al. Int. Journal of Engineering Research and Application www.ijera.com ISSN : 2248-9622, Vol. 7, Issue 1, ( Part -3) January 2017, pp.11-18 m of a particle in the field direction is described by Langevin expression. m = Md [coth ξ – 1/ξ] Where, ξ = (mHo/ kT). The behavior of the ferrofluid depends upon the behavior of individual particle. The Brownian relaxation time τB = 3 Vη / kT, Neel relaxation time σ τN = τO ℮ affects the susceptibility of the particle, where V is the hydrodynamic volume of a particle, η is the dynamic viscosity of the carrier liquid, σ is associated with anisotropy of the crystal K and given with KV / kT and τO, the damping or extinction time Figure 2(a). TEM of Fe3O4 system with 21 nm particle -9 size ferrofluid. is about ~10 seconds. In Neel relaxation, the magnetic moment may change or reverse the direction within the particle without the rotation of the particle. This is achieved by overcoming the energy barrier. The probability of such a transition is approximately equal to ℮σ. It is interesting that when τN = τB, one can determine critical particle radius; above this radius, the Brownian relaxation mechanism occurs and below this, is the relaxation by Neel’s mechanism. The total susceptibility of the ferrofluid depends on number of particles contribution. The Xi can be shown as a function of volumetric fraction Фm. Where Xi = (π/18) (Фm) 2 3 (μ0Md d /kT). The mean particle size was d≈21 nm in this work. The volume concentration Фt of the Figure 2(b). XRD pattern of Fe3O4 powder. particles coated with oleic acid in the carrier has Ф =0.08. The carrier used was transformer oil for its Table 2. d-spacing and 2theta values for Fe O powder t 3 4 stability at higher temperature. IV. MAGNETIZATION OF MAGNETIC NANOPARTICLES Magnetization of nanoparticles of magnetite is studied under applied transient field at various packing fractions [11]. Field induced particle alignment and magnetization of ferrofluid was also studied [12]. Magnetization of particles was deliberated that the shell of the particle affects The structural properties of produced magnetization of the particle [13]. However nanoparticles were analyzed by XRD taken on classically, a mathematical modeling on Philipsmake X’pert PRO model XRD machine as magnetization of particle is carried out and magnetic shown in Fig 2(b).
Load more

Recommended publications
  • Public Address System
    Hkkjr ljdkj &GOVERNMENT OF INDIA jsy ea=ky;& MINISTRY OF RAILWAYS ¼dk;kZy;hu iz;ksx gsrq½& (For official use only) MAINTENANCE HANDBOOK ON PUBLIC ADDRESS SYSTEM CAMTECH/S/PROJ/12‐13/HB‐PA/1.0 December 2012 MAHARAJPUR, GWALIOR – 474 005 CONTENTS Sr. No. Description Page No. 1. Introduction 1 2. Acoustic 2 3. Microphones 7 4. Loudspeaker 16 5. Amplifier 24 6. Audio Mixer Pre-Amplifier 37 7. Coference System 40 8. Maintenance 47 9. Wiring and Cabling 49 10. Earthing and other Safety Precautions 51 11. PA System at Railway Stations 53 12. Fault Finding 55 13. Precautions 58 ISSUE OF CORRECTION SLIPS The correction slips to be issued in future for this handbook will be numbered as follows: CAMTECH/S/PROJ/2012-13/HB-PA/1.0/C.S.# XX date-------------------------------- Where “XX” is the serial number of the concerned correction slip (starting from 01 onwards) CORRECTION SLIPS ISSUED Sr. No. of Date of Page No. and Item no. Remarks Corr. Slip issue modified CAMTECH/S/PROJ/12‐13/HB‐PA/1.0 1 PUBLIC ADDRESS SYSTEM 1. Introduction Public Address System (PA system) is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeakers, used to allow a person to address a large public, for example for announcements of movements at large and noisy air and rail terminals. The simplest PA system consist of a microphone, an amplifier, and one or more loudspeakers is shown in fig 1. A sound source such as compact disc player or radio may be connected to a PA system so that music can be played through the system.
    [Show full text]
  • Title: JBL's Differential Drive® Transducers
    Technical Note Volume 1, Number 33 Title: JBL's Differential Drive® Transducers 1. Introduction: Differential Drive technology in detail. JBL Professional introduced the Differential 2. Anatomy of a Differential Drive transducer: Drive concept in the EON System in 1995 as a means of attaining maximum system perform- The simplest way to understand Differential Drive is ance with minimum weight. Compared with tra- to compare it directly with JBL’s traditional motor ditional driver designs, JBL’s patented structures. Figure 1 shows a section view of a tradi- Differential Drive makes use of a pair of in-line tional JBL magnet-voice coil assembly and a voice coils in separate magnetic gaps instead Differential Drive system. As a starting point, let us of a single voice coil-gap combination. This design the Differential Drive system so that its permits a more effective use of available parameters are identical to those of the traditional space, and allows more efficient removal of motor structure, with the same electrical-to-mechani- heat from the motor structure. Specifically, the cal coupling and the same moving mass. voice coils are reversely wound and are In the traditional design, magnetic flux density B immersed in magnetic fields of opposite polari- crosses a gap in which a coil of wire of length l is ty. This ensures reduced magnetic leakage flux placed. The coil has an electrical resistance, R . and focuses more magnetic energy in the gaps E These quantities establish the value of (Bl)2/R , where it is needed. Both ferrite and neodymi- E which is the electromechanical coupling factor of the um-iron-boron (NIB) magnets can be used, driver.
    [Show full text]
  • Paper Speaker
    Paper Speaker Introduction: How do you listen to music? Whether you use headphones or a large sound system you are undoubtedly using some combination of speakers, but how do speakers create sound? In this activity you will construct your own speaker in order to learn how electromagnetism is used to fill the air with music. The sound we hear is a result of our brains interpreting the changes in air pressure detected by our ear drums. These changes in air pressure are what we call sound waves. When air is mechanically compressed and stretched the air molecules bump into each other, causing the pattern to move through the air where it hits your eardrum and your brain interprets it as a sound. This mechanical stretching and compressing of the air is caused by physical objects vibrating at various frequencies in the world around you. The faster the vibrations are the higher the frequency of the sound waves created, which your brain interprets as a higher pitched sound. A speaker is an electro‐mechanical device designed to transform electric signals into mechanical motions that generate sound. Sounds are typically stored on a computer as a compressed file that contains information about the frequency and intensity of the sound. When these files are “played” the computer decompresses the file and sends electric signals corresponding to the sound data through whatever output medium you are using. These electric signals turn on an electro‐magnet, called the voice coil, which reverses polarity depending on the signals it is receiving. A permanent magnet, located either inside the electro‐magnet, or surrounding it, forces the electro‐magnet to move up and down as the polarity changes.
    [Show full text]
  • Current-Driving of Loudspeakers
    IV First Edition 2010 Copyright © 2010 Esa T. Meriläinen All rights reserved Homepage: www.current-drive.info ISBN: 1450544002 EAN-13: 9781450544009 Published in the U.S.A. through a print-on-demand service While every precaution has been taken to ensure the accuracy of infor- mation presented herein, the author and publisher assume no responsi- bility for errors or omissions. Nor is any liability assumed for any pos- sible damages or losses arising from the use of this information. 1 SOME PARALLELS 1.1 The Era of Direct Current The issue whether loudspeakers should be excited by a voltage or current signal is quite well comparable to a dispute that took place over a century ago, concerning whether the production and distribution of electricity should operate on direct or alternating current. Thomas A. Edison had opened, in New York, the world's first power generating plant, that supplied a DC voltage of 110 volts for an area of a few square kilometres in Manhattan. Another pioneer of electrical tech- nology, Croatian-born Nikola Tesla, instead, believed strongly in the su- periority of the three-phase AC system he had developed. In 1886, George Westinghouse founded an electric company to utilize the inven- tions and patents of Tesla and to compete with Edison. Edison was not at all pleased seeing a rivaling system threatening his dominating stature in power production. The conflict caused a breach between Edison and Tesla, and a public struggle about which system would become prevalent. Edison even resorted to a trick campaign in his attempt to defame AC power, that he thought was dangerous.
    [Show full text]
  • The Weakest Link
    Innovation. Amplified. Chapter 2 The Weakest Link by Hartley Peavey he integral component of the production/repro- consisted of a paper cone driven by voice coil that Tduction of sound involves what engineers call a “reacted” with a fixed magnetic field generated by transducer. This is a device that transforms one kind an electromagnet. The electromagnet consist of of energy into another. A loudspeaker is a device that numerous turns of wire in a magnetic structure that converts electrical energy into a sound pressure wave created a “focused” magnetic field for the voice coil. that is perceived by our ears as what we call sound. This early “loudspeaker” was an instant hit and was Without getting too involved in history, we should be immediately copied by a number of people using a aware that when the telegraph was invented in the number of “variations” on the electromagnetic driver mid 1800’s, the “receiver” was an electromagnetic coil theme. that attracted a metal “armature” that made a “clicking noise” when current flowed through the coils producing What is most interesting about the loudspeaker is the familiar “click/clack” sound of the early telegraph… that while electronics has made vast improvements Even before Morse perfected the telegraph, scientists over the years, the so-called dynamic loudspeaker had discovered that certain materials possessed the has remained very much the same. Today’s speakers ability to produce electricity when they are moved or still use voice coils reacting with a magnetic field bent, and when electricity is applied to them, do the usually including some kind of fiber (paper) cone/ reverse by producing a physical motion.
    [Show full text]
  • Energy Transduction: Building a Speaker You Will Be Working in Groups of 2-3 Students to Construct Your Speaker
    Speaker Building Energy Transduction: Building a Speaker You will be working in groups of 2-3 students to construct your speaker. Please be careful with the magnets. These neodymium magnets are very powerful and can break or injure you if they snap together from a distance. Keep them at least one foot away from computers, credit cards, and other electronic devices as they can interfere with magnetic storage. Materials Figure 1: Materials for our loudspeaker • 2 Cylindrical neodymium magnets 1/2" diameter x 1/2" height • 1 Cylindrical neodymium magnet 1/2" diameter x 1/8" height • 2 Paper or styrofoam plates • 1 Index card • ≈17 feet of 30 gauge magnet wire • Masking tape • Scissors MET-lab 1 Drexel University Speaker Building Winding the "Voice Coil" 1. Cut off about a third off the length off the index card and roll it around 1 your finger. 2. Use the magnets to size the coil frame. There should be about a 1/8" gap between magnet and coil. Tape the coil 2 frame in place. 3. Leaving an extra 4-5" of wire on 3 each end, wind the coil around the frame, starting in the middle and working toward one end. Use ≥ 70 turns! Record the number 4 of turns you used below. #Turns: 4. Secure the ends of the voice coil with masking tape. You could also put 5 small pieces of tape on the end of the coil frame to keep the coil from slipping over and unwinding. 5. Very important: Scrape the enamel layer off the ends of the voice coil.
    [Show full text]
  • Permanent Magnet Loud Speaker (Moving Coil)
    Skill Based – III Audio and Video Systems Microphones andLoudspeakers 1 Unit- 1 and 2 Content Loudspeakers • Crystal Loudspeaker, • Dynamic Loudspeaker, • Electrostatic loudspeaker, • Permanent Magnet Loudspeaker, • Woofers and • Tweeters. 2 Microphones • Microphone Characteristics, • Crystal Microphone, • Carbon Microphones, • Dynamic Microphones and • Wireless Microphones. Introduction • Consumer electronics or home electronics (i.e. analog or digital) are equipment intended for everyday use, typically in homes. • Consumer electronics include devices such as – Entertainment (flat screen TVs, DVD players, video games, remote control cars, etc.), – Communications (telephones, cell phones, e-mail-capable laptops, etc.), and – Home-office activities (e.g., desktop computers, printers etc.) History 3 Component Inventor Year Application Johann Philipp An electric loudspeaker installed in 1861 Reis his telephone speaker He patented his first electric loudspeaker Alexander 1876 (capable of reproducing intelligible speech) as Loud Graham Bell part of his telephone First commercial version of the speaker Loudspeaker Loudspeaker is a transducer which converts an electrical signal into sound signal. A device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa called as transducer. Eg:- Microphone, Speaker. The lowest frequency that a human ear can hear is 20 Hz 4 Speaker Parts Characteristics • There are a number of interrelated factors that must be considered in designing transducer for converting electrical energy into acoustic energy. – sound travel fastest in Steel and cannot travel through a vacuum • These include • Electroacoustic efficiency, • Uniformity of frequency response, • Linearity of amplitude response, • Transient response, • Power handling capacity, • Size, • Durability and • Cost. 8 IdealLoudspeaker • Would have an electroacoustic efficiency approaching 100 per cent.
    [Show full text]
  • Ferrofluid Literature, Articles and Patents
    Web: http://www.pearl-hifi.com 86008, 2106 33 Ave. SW, Calgary, AB; CAN T2T 1Z6 E-mail: [email protected] Ph: +.1.403.244.4434 Fx: +.1.403.245.4456 Inc. Perkins Electro-Acoustic Research Lab, Inc. ❦ Engineering and Intuition Serving the Soul of Music Please note that the links in the PEARL logotype above are “live” and can be used to direct your web browser to our site or to open an e-mail message window addressed to ourselves. To view our item listings on eBay, click here. To see the feedback we have left for our customers, click here. This document has been prepared as a public service . Any and all trademarks and logotypes used herein are the property of their owners. It is our intent to provide this document in accordance with the stipulations with respect to “fair use” as delineated in Copyrights - Chapter 1: Subject Matter and Scope of Copyright; Sec. 107. Limitations on exclusive rights: Fair Use. Public access to copy of this document is provided on the website of Cornell Law School at http://www4.law.cornell.edu/uscode/17/107.html and is here reproduced below: Sec. 107. - Limitations on exclusive rights: Fair Use Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, includ- ing such use by reproduction in copies or phono records or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for class- room use), scholarship, or research, is not an infringement of copyright.
    [Show full text]
  • Qualitatively Describe the Application of the Motor Effect In: M-B
    Qualitatively describe the application of the motor effect in: M-B The Galvanometer - Measures the magnitude and direction of small DC currents. - A current-conducting coil of wire is connected in series - When he current flows, a magnetic field is induced around the coil which interacts with the external magnetic field of the permanent magnet. This causes the coil to experience a force due to the motor effect. - The force causes the needle to rotate and give a reading on the scale. - The needle rotates until the magnetic force acting on the coil is equalled by the counter- balancing spring. - Curved/radial magnets are used to generate a radial magnetic field. This ensures that the plane of the coil is always parallel to the magnetic field, keeping the torque constant and at a maximum. This also means that the scale of the galvanometer is linear, with the amount of deflection proportional to the current flowing through the coil. The loudspeaker - A device that transforms electrical energy into sound energy. - Consists of a permanent circular magnet that has one pole on the outside and the other on the inside. The coil of wire (voice coil) in the space between the poles is attached to the speaker cone. - When an AC current flows in the coil, it produces a magnetic field which interacts with the external magnetic field of the circular magnet. - The alternating current results in a changing magnetic force acting on the coil, causing it to move back and forth due to the motor effect. - The coil oscillates back and forth causing the membrane of the speaker cone to vibrate at the same frequency as the AC current passing through the coil.
    [Show full text]
  • Physics Chap 13
    4. When you look at the apparatus used to demonstrate the motor principle using a straight conductor (Figure 5), you can imagine that the suspended bare copper wire might act like a swing. What would you do to get the wire to swing back and forth with a reg- ular period of vibration? (With your teacher’s approval, you might be able to try your design.) Reflecting 5. The explanation of the definition of the ampere is included in this section that discusses the motor principle. Explain why this is logical. 13.6 Applications of the Motor Principle The motor principle refers to a force acting on a conductor carrying a current in a magnetic field. It is the most important principle used in the development of electric motors. However, the development of electric motors is not the only application of the motor principle. The motor principle has also been applied in the development of devices such as loudspeakers for stereos and in ammeters and voltmeters. The Moving-Coil Loudspeaker A loudspeaker reproduces sound waves by rapidly moving a paper or plastic sound cone back and forth in response to electrical signals from an amplifier. Figure 1 shows side and front views of a magnetically driven speaker. speaker electric current cone in voice coil movable voice ring coil (attached to pole speaker cone) N N SNNS Figure 1 N N In a moving-coil loudspeaker, a movable coil field lines is attached to the sound cone and placed central of magnet over the central shaft of a tubular permanent pole magnet.
    [Show full text]
  • Finemotor™ T U T O R I
    FINEMotor™ Magnet System & Voice Coil Design Program T U T O R I A L 1 The FINEMotor program is ideal for simulating and designing the magnet system and voice coil for any kind of loudspeaker driver. This includes not only woofers and domes but also telephone receivers and headphones etc. 6.5” Woofer Design Start FINEMotor and select “New” or _Default.fm3. We will try to use an existing voice coil with Kapton former and winding width of 9.75mm and VCID= 25.60mm. Press the “Voice Coil” button: 2 We have selected a 2 layer round wire copper voice coil and set Re=6.2 ohms, plus set Kapton as Former Material (Use the Kapton setting for all non-conducting VC formers). Note “Wire Stretch” is set to 4% to match our existing voice coil. Press “Apply Now”. Click on the upper left window and mouse drag to get close to the 9.75mm winding width. “Mechanical Parameters” shows the winding width to be 9.69mm using 0.17mm wire, which is really close. Note: In a nominal 8 ohms system you can often go down to DCR= 5.5 ohms (or even lower) and still keep the minimum impedance of 6.4 ohms. This is because the min. impedance (Zmin) is normally at least 0.5 ohms higher than DCR, and the inductor in the cross-over normally has a resistance (RL) of 0.3-0.5 ohms or more. – Likewise a nominal 4 ohms system can use a DCR of 2.5-3 ohms or lower while keeping the min.
    [Show full text]
  • Public Address System Iriset
    TC 2 PUBLIC ADDRESS SYSTEM IRISET Ver 1.0 TC2 Public Address System 1 AGENDA • Application of PA system • Acoustics • Microphones • Loud speakers • Amplifiers • Planning of PA • Installation • Special types of PAIRISET systems • Phasing and matching methods Ver 1.0 TC2 Public Address System 2 What is a PA system ? • P.A. System is a type of communication, which can be used to communicate to a limited public over a limited area. • The basic function of an audio system is to deliver audible and recognizable sounds at comparable level to the listener. IRISET • PA system comprises all the devices and networks that exists between a source of sound (or its electrical Ver 1.0 TC2 Public Address System 3 equivalent) and its point of final reproduction. Application of P.A. system in Railways IRISET Ver 1.0 TC2 Public Address System 4 • Passenger amenity • Marshalling Yards • Breakdown Train Emergency Equipment • Special Functions • Railway Workshops • Conferences IRISET Ver 1.0 TC2 Public Address System 5 Acoustics Acoustics is defined as the "Scientific Study” of Sound, especially of its generation, propagation, reception and interaction with materials and is further described as the "total effect of sound” especially as produced in an enclosed space. IRISET Ver 1.0 TC2 Public Address System 6 Terms related to the study of Acoustics IRISET Ver 1.0 TC2 Public Address System 7 Intensity: The intensity I, is the sound power passing normally through a unit area of space. This relates to amplitude of acoustic force. It is expressed in W/m2 Loudness: It is the intensity of the sound stimulus as perceived by the human ear and chiefly a function of sound pressure.
    [Show full text]