Showing posts with label Speakers. Show all posts
Showing posts with label Speakers. Show all posts

2/14/2015

Speakers

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So amplifiercircuit will try to do a definition of speakers, are one of the most common output devices used with computer systems. Speakers are transducers that convert electromagnetic waves into sound
Speakers
waves. The speakers receive audio input from a device such as a computer or an audio receiver. This input may be either in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since sound waves are produced in analog form, digital speakers must first convert the digital input to an analog signal, then generate the sound waves. The sound produced by speakers is defined by frequency and amplitude. The frequency determines how high or low the pitch of the sound is. For example, a soprano singer's voice produces high frequency sound waves, while a bass guitar or kick drum generates sounds in the low frequency range. Many speakers include multiple speaker cones for different frequency ranges, which helps produce more accurate sounds for each range. Two-way speakers typically have a tweeter and a mid-range speaker, while three-way speakers have a tweeter, mid-range speaker, and subwoofer.
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8/16/2014

250 W Stereo Audio Amplifier Class-T

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GENERAL DESCRIPTION:

The TA0103A is a 250W continuous average (4Ω ), two channel Amplifier Driver Module which uses Tripath’s proprietary Digital Power Processing (DPPT M ) technology. Class-T amplifiers offer bot h the audio fidelity of Class-AB and the power efficiency of Class-D amplifiers. 

Applications:
  • Audio/Video 
  • Amplifiers/Receivers 
  • Pro-audio Amplifiers 
  • Automobile Power Amplifiers 
  • Subwoofer Amplifiers 
  • Home/PC Speaker Systems
Circuit Amplifier:
250 W Stereo Audio Amplifier Class-T

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4/15/2014

Satellite + Subwoofer 3-Speaker System Electronics Crossover IC

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  • CMOS Technology 
  • Low Power Consumption 
  • 2 Built-in Individual Volume Control: 0 dB to -60dB 
  • 2-Channel 2nd Order High Pass Filter + 1 Mixed Mono Subwoofer Low Pass Filter 
  • Cross-Over Frequency adjustable by external passive components 
  • Control Interface of Volume Control: UP/DOWN Key (MCU is not necessary) 
  • Built-in 3D Effect and Loudness Function 
  • Supply Voltage: 5V to 9V
Satellite + Subwoofer 3-Speaker System Electronics Crossover IC

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3/30/2014

Speaker indicator

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With this indicator you can see how much power an amplifier delivers. The circuit uses a LM 3915, the logarithmic variation of the known LED VU meter IC LM 3914. The circuit is connected directly to the speaker output of the amplifier, and the power state of 0.2 watts to 100 watts. The sensitivity of the circuit can be varied with R1. The basic settings are shown in the table.
 
  • R1 = 10 k (see text)
  • R2 = 10 k
  • R3 = 390 Ω
  • R4 = 2.7 K?
  • C1 = 22 V μF/25
  • LED1-LED10 = LED (color of choice)
  • IC1 = LM 3915

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Subwoofer Amplifier 40W

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Description

This amplifier delivers massive power and uses one IC and two power transistors. The circuit consists of an amplifier IC (a TDA 2030A) and a power stage consists of two transistors.  Amplifier can be powered with an asymmetrical supply voltage of 12 to 44 V.

Circuit Diagram:


Subwoofer Amplifier 40W
Subwoofer Amplifier 40W

Part-list:

  • R1-R3, R7 = 100 K?
  • R6 = 8,2 kW
  • R4, R5, R8, R9 = 1.40 Ω 1%
  • R10 = 1 Ω
  • C1 = 470 nF
  • C2 = 10 V μF/63
  • C3 = 4.7 V μF/63
  • C4, C5, C7 = 220 nF
  • C6 = 2200 V μF/50
  • C8 = 1000 V μF/50
  • D1, D2 = 1N4001
  • T1 = BD712 or BD912
  • T2 = BD711 or BD911
  • IC1 = TDA2030A
  • LS = speaker - 4/8 Ω
  • Cooling = Fisher SK08/75
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2/02/2014

Crowbar Speaker Protection

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Description
Crowbar circuits are so-called because their operation is the equivalent of dropping a crowbar (large steel digging implement) across the terminals. It is only ever used as a last resort, and can only be used where the attached circuit is properly fused or incorporates other protective measures.

A crowbar circuit is potentially destructive - if the circuitry only has a minor fault, it will be a major fault by the time a crowbar has done its job. It is not uncommon for the crowbar circuit to be destroyed as well - the purpose is to protect the device(s) attached to the circuit - in this case, a loudspeaker.



There's really nothing to it. A resistor / capacitor circuit isolates the trigger circuit from normal AC signals. Should there be enough DC to activate the DIAC trigger, the cap is discharged into the gate of the TRIAC, which instantly turns on ... hard. A TRIAC has two basic states, on and off. The in-between state exists, but is so fast that it can be ignored for all intents and purposes.

The BR100 DIAC (or the equivalent DB3 from ST Microelectronics) is rated for a breakdown voltage of between 28 and 36V - these are not precision devices. Needless to say, using the circuit with supply voltages less than around 40V is not recommended, as you will have a false sense of security. The supply voltage must be higher than the breakdown voltage of the DIAC, or it cannot conduct. Zeners cannot be used as a substitute for lower voltages - a DIAC has a negative impedance characteristic, so when it conducts, it will dump almost the full charge in C1 into the gate of the TRIAC. This is essential to make sure the TRIAC is switched into conduction.

The TRIAC is a common type, and may be substituted if you know the specifications. It's rated at 12A, but the peak current (non-repetitive) is 95A, and it only needs to sustain that until the fuse (or an output transistor) blows. A heatsink is preferred, but there is a good chance that the TRIAC will blow up if it has to protect your speakers, so it may not matter too much. The 0.47 ohm resistor is simply to ensure that the short circuit isn't absolute. This will limit the current a little, and increases the chance that the TRIAC will survive (albeit marginally). Feel free to use a BT139 if it makes you feel better - these are rated at 16A continuous, and 140A non-repetitive peak current.

The peak short circuit current will typically be about 90A for a ±60V supply, allowing ~0.2 ohms for wiring resistance and the intrinsic internal resistance of the TRIAC, plus the equivalent series resistance of the filter capacitors. That's a seriously high current, and it will do an injury to anything that's part of the discharge path. Such high currents are not advised for filter caps either, but being non-repetitive they will almost certainly survive.

Construction & Use

Apart from the obvious requirement that you don't make any mistakes, construction is not critical. Wiring needs to be of a reasonable gauge, and should be tied down with cable ties or similar. C1 must be polyester. While a non-polarised electrolytic would seem to be acceptable, the circuit will operate if the capacitor should dry out over the years. This means it will lose capacitance, and at some point, the crowbar may operate on normal programme material. This would not be good, as it will blow up your amplifier!

Make sure that all connections are secure and well soldered. Remember that this is the last chance for your speakers, so it needs to be able to remain inactive for years and years - hopefully it will never happen. The circuit doesn't have to be mounted in the amplifier chassis - it can be installed in your speaker cabinet. Nothing gets hot unless it operates, at which point no-one really cares - it just has to save the speakers from destruction once to have been worthwhile.

Remember that the crowbar circuit absolutely must never be allowed to operate with any normal signal. A perfectly good amplifier that triggers the circuit because of a high-level bass signal (for example) will very likely be seriously damaged if the crowbar activates. To verify that no signal can trigger it, you may want to (temporarily) use a small lamp in place of R2, and drive the amp to maximum power with bass-heavy material.

A speaker does not need to be connected. If the lamp flashes, your amp would have been damaged. If this occurs, you may want to increase the value of C1. Note that bipolar electrolytics should never be used for C1, because they can dry out and lose capacitance as they age. This could cause the circuit to false-trigger.
Origianl article sourse learningelectronics.net
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1/26/2014

FAQ on the speakers and subwoofer

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Introduction

Recently could hear a lot of questions about speakers and subwoofers. The vast majority of responses can be found on the first three pages of any book written by professionals. Material is addressed primarily to beginners, lazy ;) and rural Homebrew, prepared on the basis of books I.A.Aldoschinoy, V.K.Ioffe partly Ephrussi, journal publications in Wireless Worrld, AM and (some) personal experience. NOT used information from the Internet and Fidonet. The material is in no way purport to lighting problems, and is an attempt to explain the basics of acoustics on the fingers.

Most often, the question goes something like this: "the speaker found that to do with it?" Or "tovarischch and say such subwoofers are>." Here we consider only one solution to this problem: For existing dynamics to make a box, with the optimal settings for HCH as possible. This option differs from the task factory designer-pull system to lower the frequency of the required quantity of TU

[Q] Hashel large speaker on the occasion unmarked. How to know whether you can make him a subwoofer?

[A] Hujno measure its T / S parameters. Ha Based on these data to decide on the form of HCH clearance.

[Q] What is the T / S parameters?

[A] The minimum set of parameters for the calculation of HCH design proposed by Till and Small.
Fs-resonant frequency of the speaker without registration
Q factor Qts-full dynamics
Vas-equivalent volume of the speaker.

[Q] How to measure the T / S parameters?

[A] To do this, you need to collect from the generator circuit, a voltmeter, a resistor, and the test speaker. The speaker is connected to the output of the generator with an output voltage of several volts across the resistor of about 1 kOhm.

1. Remove V (F) = AFC resistance dynamics in the resonance region. The speaker must during this measurement to be in the free space (the distance from the reflecting surfaces). Hahodim speaker impedance on the current fasting person (useful), write in the air resonance frequency Fs (this is the frequency at which the voltmeter maximal :), the voltmeter Uo at minimum frequency (well, for example 10 Hz) and Um at the resonance frequency Fs.

2. Hahodim frequencies F1 and F2, in which the curve V (F) intersects the level of V = SQRT (Vo * Vm).

3. Hahodim Qts = SQRT (F1 * F2) * SQRT (Uo / Um) / (F2-F1) is the total quality factor of the dynamics, we can say, the most important value.

4. To find Vas need to take a small indoor Boxes volume Vc, with a hole a little smaller than the diameter of the diffuser. Tightly to lean to the speaker hole and repeat the measurements. From these measurements, you will need a resonant frequency dynamics in the housing Fc.Hahodim Vas = Vc * ((Fc / Fs) ^ 2-1).

This procedure is written in the audio shop • 4 for 99 year. I had checked it out .. There are others, when measured mechanical properties of the head, weight, flexibility, etc.

[Q] I now have options speaker, what to do?

[A] Each speaker in the design sharpen a certain kind of acoustic design. To find out under what is, look at the quality factor.
Qts> 1,2 it heads for the open boxes, optimally 2.4
Qts <0.8-1.0 - head for closed boxes, optimally 0.7
Qts <0.6 - for bass reflex, optimum - 0.39
Qts <0.4 - for horns

Wise to sort head is not on good quality and value for Fs / Qts. Cite from memory, the reluctance of the formula to calculate.
Fs / Qts> 30 (?) Screen and open housing
Fs / Qts> 50 closed body
Fs / Qts> 85 Tubes
Fs / Qts> 105 Bandpassy (bandpass resonators)

Elasticity, meatiness, dryness and other similar characteristics of the sound emitted by Bass speakers, are largely determined by the transient response of the system formed by the speaker, woofer design and the environment. To this system was not to release the impulse response, its quality factor should be less than 0.7 for systems with one side of the radiation dynamics (closed and phase inverter) and 1.93 for two-way systems (design type screen and open box)

[Q] Where to read about the open design?

[A] Open boxes and screens is the simplest type of decoration. Pros: ease of calculation, no increase in the resonant frequency (the size of the screen depends only view of the frequency response), almost constant quality factor. Disadvantages: large size of the front panel. Sufficiently competent and simple calculations of this type of design can be found in VK Joffe M.V.Lizunkov. Household speakers, M., Radio and Telecom.1984. And in the old Radio certainly have primitive amateur calculations.

[Q] How to calculate the closed box?

[A] Making "closed box" is of two types, infinite baffle and suspension compression. Getting into a particular category depends on the ratio of suspension dynamics and flexibilities in the air box, denoted alpha (by the way, you can try on the first and second count and change by filling).For an infinite screen ratio is less than 3 flexibilities for suspension compression more than 3-4. Can be considered as a first approximation that the heads with high Q sharpened by an infinite baffle, with less-under suspension compression. Taken to advance the speaker enclosure is closed infinite baffle has a larger volume than the compression box. (Generally speaking, when there is a speaker, the optimal body under it is clearly a certain amount. Errors encountered when measuring the parameters and calculations, can be slightly corrected by filling).Speakers for closed shells have powerful magnets and soft suspensions unlike heads for the open boxes. The formula for the resonant frequency of the dynamics in the design of volume V Fc = Fs * SQRT (1 + Vas / V), and an approximate formula relating the resonant frequency and quality of the head in the body (the subscript "c") and open space (subscript "s") Fc / Qtc = Fs / Qts

In other words, it is possible to implement the required quality factor only way speaker system, namely the choice of the volume of a closed box. What is the quality factor to choose? People who have not heard the sound of natural musical instruments, usually choose speakers with Q bolee1 0. In columns with a quality factor (= 1.0) the smallest uneven frequency response in the lower frequencies (and what does that sound?) Achieved at the cost of a small release on the transient response. Maximally smooth frequency response is obtained when Q = 0.7, and fully aperiodicity impulse response with Q = 0.5. Homogrammy for calculations can be taken in the above book.

[Q] Articles about speakers often words like "approximation of Chebyshev, Butterworth," etc. How does this relate to the speakers?

[A] The speaker system is a high-pass filter. The filter can be described by the transfer function. Transfer characteristic is always possible to fit a known function. In the theory of filters use several types of power functions, named for mathematicians first licked a particular function.Function determined by the order (maximum exponent, ie H (s) = a * S ^ 2 / (b2 * S ^ 2 + b1 * S + b0) has the second order) and the set of coefficients a and b (from these coefficients You can then move on to the values ​​of the real elements of the electric filter, or electro-mechanical parameters.) Next, when it will go on the approximation of the transfer characteristic polynomial Butterworth or Chebyshev or something else, it should be understood so that the combination of the properties and dynamics of the body (or containers and inductance in an electric filter) turned so that most accurately the frequency and phase characteristics can be adjusted to a particular polynomial. Most smooth frequency response is obtained if it can be approximated by a polynomial Butterworth. Chebyshev approximation is characterized by the wave-frequency response and a large stretch of the working area (according to GOST to -14 dB) in the region of lower frequencies.

[Q] What kind of approximation to select the phase inverter?

[A] So before the construction of a simple bass reflex need to know the volume of the box and reflex tuning frequency (pipes, holes, passive radiator). If as a criterion to select the most smooth response (and this is not the only possible criterion), we get the following label A) Qts <0,3-most smooth curve will kvazitretego order B) Qts = 0,4 - better described battervortovskimi curves in) Qts > 0.5 - will allow the waves on the AFC, Chebyshev. In case A) bass reflex tuned to 40-80% higher than the resonance frequency in case b), the frequency of resonance, in case B) below the resonance frequency. Also in these cases will be a variable volume enclosure .. In order to find the exact frequency tuning, we must take the original formula, rather cumbersome to bring them here. Therefore, I refer interested in AudioMagazin 1999, then there is an educational program can be sorted out, or book Aldoshina. And even in the article Ephrussi Radio for '69 amiss.

Conclusion

If after reading all this, you still have the desire to rivet something yourself, you can take online nifty program type WinspeakerZ and calculate it all myself, remembering that of G.. candy not do. Not to be carried away by a decrease of the cutoff frequency, in any case, do not try to compensate for the roll off the amplifier. AFC can be leveled and a little bit, but the sound is enriched harmonics and subharmonics weight.On the contrary, the best results, in terms of pleasantness to the ear can be achieved forcibly ruining inlet UM very lowest frequencies, iefrequencies below the cutoff frequency HCH column. Another remark concerning the phase inverter configuration error in the resonance frequency of the phase inverter 20% leads to a surge or decline in response at 3 dB.

Oh, I almost forgot to say about subwoofers that actually strip resonators. Q-factor of the speakers for them should be even lower. The simplest bandpass too incalculable, but this ends my courtesy.
Original article sourse cxem.net
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1/24/2014

UM protection unit and acoustics overcurrent

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It is based in protection circuit Audio Analogue Aida - from the site of its designer Federico Paoletti . I developed it a little bit and used in his new mobile amplifier - also borrowing from Paoletti. The scheme is applicable to any PA whose output - compound emitter follower (2 stages or more, or a Darlington Naturally - silicon, or a cascade of CMOS).
In the original scheme in the traditional circuit protection (voltage drop across the emitter resistor opens key bypass transition BE composite output transistor) added two optocoupler (circuit shunt base for the upper and lower arm). Current drawn from the shunt base flows through the LED of optocoupler and opens galvanically isolated key. Fine, but the same node can not just arbitrarily turn off power, but doing it on the pitch outside. Need another pair of optocouplers, shunt BE transitions output transistors:


Threshold set divider R1-R2 based on the current limit for each transistor and the emitter resistance in the circuit output. The total resistance R1 + R2 must be in the range 10 .. 100 ohms. Thanks circuit R3-C1-R4-D1, R8-C2-R9-D2 (LPF) threshold DC is much higher than the AF.Furthermore, the threshold decreases with increasing temperature T1, T2.
The first and fourth (vertical) optocouplers - security sensors (closed = alarm), second and third - the keys controlled by an external signal (sink current = off UM). In the chain of forced shutdown necessarily provide current-limiting resistor. Resistors R9-10 - I put instead of jumpers on the board, whether they are as such - probably not.

Despite the additional voltage drop across the LED, the scheme is guaranteed off the PA with a repeater on single and dual Darlington (0.33 ohms under the emitter). The main thing that current drawn T1, T2 in the "triangle" - the voltage amplifier - was sufficient to guarantee the inclusion of optocouplers (not less than 1 mA for TLP521). Optocouplers - any except Darlington (well, they go to hell, and do not need much gain here). Requires current transfer ratio is determined by currents and levels of automatic protection, as well as current shunt which will select from the "triangle". T1, T2 - any thin with low saturation voltage.

Incidentally, memorized by heart half volt LED on - not quite right. The LED TLP521 in this scheme falls at room temperature not more than 0.9V.

When designing the board first, "the mind" is placed own mind and protection circuit - second. In this "ground" defense to hold separate and connect with other "lands" at a common point "star." If a car amplifier analog ground unleashed current board of land and automation unit usually sits on the board, the circuit R4D1 R9D2 connect with analog power and ground otpronov - with on-board.
Original article sourse cxem.net
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Protection device speakers

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In life, frequent situations where, for whatever reason speakers connected to an audio amplifier, the power of which exceeds the maximum allowed for a system that, on the one hand, often produce the best sound quality, increase the dynamic range, with another - increases the risk of damage due to overload dynamic heads. This is especially true when using the speaker on school, student, youth parties, where the acoustics are often connected to the first that fell known good amplifier that is "powerful." To prevent damage to the speakers when applying for her power, exceeding the nominal, it is necessary to equip the unit overload protection, built-in speakers and requires no additional power supply. Schematic diagram of such a device designed to protect the AC power 10 ... 35 W is shown in below


Protection device speakers circuits


Also in case of overload tripping SS, this device also protects it from damage by the dynamic head in the event of failure of the transistor amplifier and its output appears on the DC voltage. The device is connected to the output of the power amplifier audio frequency. The AC voltage is rectified by a bridge diode VD1. Resistor R1 eliminates the influence of a job amplifier. The rectified voltage is smoothed oxide capacitors NW, C2. While the output power of the amplifier does not exceed the maximum allowable for the AU, the voltage at the capacitor C2 is small, the zener diode VD3 closed, hence also closed and SCR VS1. In the micro-current SCRs of this type are controllable, ie, they can close the control voltage. Since VS1 is closed and will be closed transistor VT2. K1 relay contacts are closed, dynamic head at AU will do 100% of capacity. As soon as the output power of the amplifier exceeds permissible for AC voltage on C2 increases so that opens zener VD1, open SCR VS1 and the transistor VT2, K1 relay contacts open, the power supplied to the speakers will be limited by resistors R11-R13. These load resistors are a power amplifier, which improves stability of the amplifier in case of disconnection of speaker system, moreover, these resistors reduces arcing between the relay contacts when closing and opening. When protection against overload LED lights HL1. Transistor VT1, emitter junction which operates as a diode with a micropower voltage stabilization 7 ... 12 V protects the FET from the breakdown of a gate insulator. Once the voltage at the amplifier output is reduced, zener VD3 closes closed VS1, VT2, relay K1 is closed, on the AU will come back full power. Resistor R8 introduces small hysteresis to prevent cyclic circuit-opening relay contacts at a constant power output, slightly higher than the threshold. R9 resistor reduces the current through the relay coil by opening its contacts, capacitor C6 accumulates enough energy required for reliable operation of the relay.

When placing the speaker structure within the housing structure elements operate in a fairly strong vibrations in a wide range of sound frequencies produced by the dynamic head, moreover, in some cases, should also be considered an alternating magnetic field from the dynamic head. PCB should be located at a maximum distance from the open magnetic systems dynamic heads.

The device used fixed resistors MLT, Cl-4, C2-23 or imported analogues. Trimmer R3 is desirable to use a sealed enclosure, for example, SP4-1, GPA-16c, SP5-16A, SDR-19a-3 SP4. After setting up the rotation axis of the resistor must be assigned a drop of paint. Capacitor C1 terephthalate film ethyl K73-17, K73-9 or similar. C4 - ceramic K10-17, CM-5, oxide capacitors - K50-35 or imported analogues. NW capacitor can be formed from two 470 uF (provided on the circuit board). If necessary, the capacitor C6 also be used for the operating voltage of 100 V. In the case when the device is applied with amplifiers having a supply voltage output stages more than ± 50 V electrolytic capacitors need to be at the voltage of 160 V, the power and the resistance of resistors Rl, R2 , R9 also need to increase. Capacitors NW, C6 set parallel to the PCB, and further secured with wire clamps on it. Diode bridge can be replaced by a similar low-power, for example, DB103-DB107, RB153-RB157 or make up of four rectifier diodes with a working voltage of at least 100 V. Instead KD243A can install any of a series of KD243, KD247, KD208, KD105, 1N4002-1N4007. 1N4738A Zener diode can be replaced by KS175A, KS175ZH, KS126K LED - any other. Instead trinistor KU112A can apply CG 112 AM in the TO-92. N-channel field effect transistor in this embodiment IRF9540 can operate without the heat sink. Its maximum drain-source voltage of 100 V, the domestic counterpart - KP785A. Instead, the transistor can be used IRF9634, KP796A having UCH MAX> 250 V. Instead KT315A can apply any of the series KT312, KT315, SS9014. Relay K1 - REC-29, passport DUSCH4.501.56.Resistance of the coil of the relay about 950 ohm stable switching contacts occurs at a voltage of 15 V, the minimum voltage retention - 7 V. This type of relay modules used in the control of domestic TV USTST. For replacements, consider the fact that the contacts of the relay must commute significant current.

PCB protection device speakers 
The apparatus may be mounted on a printed circuit board size 140x50 mm, wherein all the elements are installed than the LED. On Figure 2shows the circuit board from the conductors. 
From the installation fee is desirable to cover three or four thin layers of epoxy glue. Each subsequent layer is applied after setting the previous one. Fee is attached to the body with five screws inside AU MOH or screws. If possible it is desirable to close deaf thick-walled (> 0.5 mm) casing, which also reduce the probability of failure of the device due to vibrations in the powerful speakers, as well as reduce the likelihood of contact bounce relay. 
Manufactured author two instances these devices are used in conjunction with speakers 15AS-220, which uses dynamic head 25GDN-3-4.These systems start to wheeze and rattle when the input power more than 40 watts. Protection threshold set to 25 watts. These speakers are powered by an amplifier "Orbit UM-002 stereo", 
which is able to develop power above 50 watts at 4 ohms. Other two copies installed in homemade sealed AC collected on broadband heads 10GDSH-1 powered by an amplifier "Corvette 50U-068 C". On threshold of protection is also installed at the rate of 25 watts of amplifier at 4 ohms. If you are working with powerful speakers (> 35 ... 5O W) and a powerful amplifier SCR will close at too low power for this case, the resistance of the resistors R4 and R7 can be doubled. 
This device can be modified by setting instead of fixed resistor R2 thermistor NTC resistance of 3.3 ... 4.7 ohms at 25 ° C, which, through a pad of heat conductive rubber should be rigidly secured to the magnetic system, a powerful low frequency driver. In this case, strong heating of the magnetic system will include device protection with less output power amplifier.
Original article sourse cxem.net
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