Circuit Schematic learn

The chip on which the amplifier is based, a Type LM3876, is a member of the Overture family from National Semiconductor, All members of this family are pin-compatible and mutually interchangeable. They are typified by an internal protection (called SPIKE). In practice, the diftection ference between them is the power output. The series was described on the basis of the LM3886 in an earlier issue*.

The PCB has been designed so what it can accommodate the LM3876 (50W) as well as the LM3886 (150W). Because of this, pin5 of the IC on the board is connected to the positive supply line. This connection is not needed for the LM3876, since its pin5 is not (internally) connected (NC).

The IC is located at the side of the board to facilitate fitting it to a heat sink as shown in the photograph.

An important aspect for optimum performance is the decoupling of the unregulated supply lines by C 7-10. All earth connections go to a single terminal on the board.

Air-cored inductor L1 consists of 13 turns of 1mm dia. enamelled copper wire with an inner diameter of 10mm. The completed inductor is pushed over R7 and its terminals soldered to those of the resistor.

All electrolytic capacitors must be mounted upright. The amplifier can be muted with a single-pole switch connected to the MUTE input (pin8). This function is enabled when the switch is open. If muting is not required, solder a wire bridge across the mute terminals on the board.

Boucherot network R6-C6 is not normally required in this application, but provision has been made for it for use in other applications.

According to the manufacturers, both chips are optimalized for a load of 8 Ohm. The output power is lower when a 4 Ohm load is used or when the supply voltage is reduced. When a 4 Ohm load is used, the SPIKE protection becomes active when the supply voltage is about 27V, resulting a in a reduction of the power output to 10W. This means that it is not advisable to use loudspeaker with an impedance <8 ohm.

For best result you can expand power amplifier using BPA-200 Amplifier

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Part listResistor:
R1, R3 = 1 k
R2, R4, R5 = 18k
R6 = see text
R7 = 10R, 5 Watt
R8, R9 = 22k

Capacitors:
C1 = 2.2 uF
C2 = 220 uF, 160 V
C3 = 22 uF, 40 V
C4 = 47 pF
C5 = 100 uF, 40 V
C6 = see text
C7, C8 = 100 nF
C9, C10 = 1000 uF, 40 V

Inductors:
L1 = 0.7 uH - see text

Integrated circuits:
IC1 = LM3876T

Miscellaneous:
Heat sink for IC1 <1.5 k w-1
Single-pole switch - see text
Schematic and PCB Layout LM3876

Parts:

R1_____________1M5 1/4W Resistor
R2____________15K 1/4W Resistor
R3___________100K Linear Potentiometer
R4_____________2K2 1/4W Resistor

C1___________330nF 63V Polyester Capacitor
C2___________100µF 25V Electrolytic Capacitor

D1_____________3mm. Red LED

IC1___________7555 or TS555CN CMos Timer IC
IC2___________4017 Decade counter with 10 decoded outputs IC

SW1___________SPST Slider Switch

B1______________9V PP3 Battery

Clip for PP3 Battery

Two Earclips with wires (see notes)

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Device purpose:

Owing to the recent launching in Europe of Cranial Electrotherapy Stimulation (CES) portable sets, we have been "Electronically Stimulated" in designing a similar circuit for the sake of Hobbyists. CES is the most popular technique for electrically boosting brain power, and has long been prescribed by doctors, mainly in the USA, for therapeutic reasons, including the treatment of anxiety, depression, insomnia, and chemical dependency. CES units generate an adjustable current (80 to 600 microAmperes) that flows through clips placed on the earlobes. The waveform of this device is a 400 milliseconds positive pulse followed by a negative one of the same duration, then a pause of 1.2 seconds. The main frequency is 0.5 Hz, i.e. a double pulse every 2 seconds. Some people report that this kind of minute specialized electrical impulses contributes to achieve a relaxed state that leaves the mind alert.
Obviously we cant claim or prove any therapeutic effectiveness for this device, but if you are interested in trying it, the circuit is so cheap and so simple to build that an attempt can be made with quite no harm.

Circuit operation:

IC1 forms a narrow pulse, 2.5Hz oscillator feeding IC2. This chip generates the various timings for the output pulses. Output is taken at pins 2 & 3 to easily obtain negative going pulses also. Current output is limited to 600µA by R2 and can be regulated from 80 to 600µA by means of R3. The LED flashes every 2 seconds signaling proper operation and can also be used for setting purposes. It can be omitted together with R4, greatly increasing battery life.

Notes:

• In order to obtain a more precise frequency setting take R1=1M2 and add a 500K trimmer in series with it.
• In this case use a frequency meter to read 2.5Hz at pin 3 of IC1, or an oscilloscope to read 400msec pulses at pins 2, 3 or 10, adjusting the added trimmer.
• A simpler setting can be made adjusting the trimmer to count exactly a LED flash every 2 seconds.
• Earclips can be made with little plastic clips and cementing the end of the wire in a position suited to make good contact with earlobes.
• Ultra-simple earclips can be made using a thin copper foil with rounded corners 4 cm. long and 1.5 cm. wide, soldering the wire end in the center, and then folding the foil in two parts holding the earlobes.
• To ensure a better current transfer, this kind of devices usually has felt pads moistened with a conducting solution interposed between clips and skin.
• Commercial sets have frequently a built-in timer. Timing sessions last usually 20 minutes to 1 hour. For this purpose you can use the Timed Beeper the Bedside Lamp Timer or the Jogging Timer circuits available on this website, adjusting the timing components in order to suit your needs.
  

The runtime of the battery of cell phone jammer can reach 160 minutes.
Android cell phone bulk delete contacts. Sometimes we need to contact to delete, especially not deleted but by selectively delete contacts, are Android phones in only one by one manually delete? This is too much trouble, if many did not half an hour to complete can not. Are there any easy way? , Delete contacts, there are two ways, first is stated above on the cell phone one by one to delete, and another is to use the Gmail account will sync contacts to your cell phone Android cell phone bound, on the contrary Android cell phone on the contacts can also choose to sync to Gmail account contacts. The price of cell phone jammer will be lower if you buy a large quantity.
So we can use the second method for rapid bulk delete contacts operation. Here are the steps: Gmail mailbox into the bound on the Android cell phone on a PC, operating one of the contacts, delete contacts, removal is complete, and then on the cell phone contacts can be synchronized. Android cell phone WIFI connection but can not access. Some of the Android cell phone users will encounter this problem when the cell phone WIFI wireless network connection, you can connect to the wireless network, and the signal is very good, but the use of certain network support software (such as the Browser Shique or Market) is not working, there is a big delay. How is this going? cell phone jammer equips with the dedicated operation status indicator.
But problems may be due to the switching network standards, then the wireless router set to 802.11g, of course, 802.11b can, but at a slower pace. Since then, Internet WIFI connection but can not be satisfactorily resolved. Android cell phone to restore the factory settings. As a smartcell phone operating system Android is also built many other smartcell phone operating system features that are common, such as mobile phones are essential to restore the factory settings. Android cell phone how to set it correctly in order to restore the factory settings do? cell phone jammer has the high security requirement.
First of all, we must be clear that the restore factory settings this feature is not frequently used, because if the misuse of the consequences are very serious, and restore the factory settings can be understood literally, all the settings in the cell phone will be restored to factory condition.

 phone jammer can be adopted in the legal proceedings.
As we all know the classic design of the BlackBerry is a large screen and easy to input QWE RTY keyboard, so the BlackBerry mobile email giant. Disadvantages: very weak in multimedia player. Palm OS-based advantages and shortcomings of the system and the advantages of the Palm OS on the PDA Palm has developed an operating system, which is the overlord of the PDA, once the S & P accounted for 90% of the PDA market share. Although its not specifically for cell phone design, but the Palm the OS of excellence and support for mobile devices also enable them to become an excellent cell phone operating system. The new version of the Palm OS 5.2. The installation position of phone jammer is not easy to be chosen for the large workshop.
Palm PDA with cell phone functions, such as the Palm Tungsten W. Handspring, Inc. (Palm, Inc. acquisition) of the Treo line is dedicated to the Palm OS mobile phones, such as the Treo 270 and the latest high-profile of the Treo 650. The dominant four years ago, Pocket PC operating system is Palm, then in high-end PDAs are invariably Palm and Sony products, and they almost always outside with the back parallel. But now the Palm operating system now has lost its place, when Sony announced its withdrawal from the international PDA market (in fact, tantamount to announcing to stop the production of the Palm OS PDA. The hanging installation of phone jammer should be adopted for this building.phone jammer can ensure the important activity will not be disturbed
For Palm, Sony PDAs with Palm operating systems), as much as an avalanche, and the fact that the exit of Sony did become a watershed Palm gloom and doom, then Palms market share is gradually being Windows Mobile eroded. Advantages: the Palm OS to run resource-less, fast processing speed, and ease of use shortcomings: a single function, user base, the support of the Chinese working platform Mana slow Mac OS X (Apple icell phone system) system and the advantages, disadvantages system and advantages of the system), Mac OS X is the latest version of Mac OS for the Apple Macintosh operating system software. The director of the workshop that several more installation position of phone jammer should be added.
Mac OS X in 2001 for the first time introduced in the market. It contains two main parts: Darwin, based on the BSD source code and the Mach microkernel-based Unix-like open-source environment used by Apple Computer and collaborative and independent developers for further development; and an Apple computer development, named Aqua GUI copyright.

The cell phone jammer company will celebrate its anniversary next month.
B, Java (Binary Runtime Environment for Wireless) game Java is a programming language, specifically what programming language we did not need to know. As a family game, we need to know two things: first, whether your cell phonesupports Java, to understand that you can access your phones manual or ask the dealer directly. Second, you choose whether to support a Java game for your mobile phone, to understand this, you can see "Why mobile game will have compatibility issues" and "how to download games from Sina for your cell phonemodel mobile cell phonegame" part of the . Here, there is a need to explain the misunderstanding that sometimes we talk about java games, often the first thought is probably the end of the cell phoneconfiguration, in fact, this is a big ideological errors. The factory inspection and acceptance personnel should sign the report of cell phone jammer if cell phone jammer is qualified.
Because the cell phoneis not a computer, "configuration" the word simply does not make sense for us. C, Brew and Java game similar, Brew (Binary Runtime Environment for Wireless) is a programming language. So the same, we do not know what Brew is to use Brew (Binary Runtime Environment for Wireless), you only need to know your cell phonecan support it. Currently, only CDMA (Code Division Multiple Access) mobile cell phoneonly support but at the same time, CDMA (Code Division Brew (Binary Runtime Environment for Wireless), Multiple Access) also supports Java, so in order to reduce costs, developers are still willing to choose the general Java-based game development. Therefore, Brew of the game is not a lot of support. cell phone jammer adopts anti-explosive and anti-removable shell of good sealing ability to prevent explosion, water and sun-burnt.
D, Uni-Java games Uni-Java is China Unicoms mobile cell phonejust to prepare for a new common development platform, Meet the group is still in development, there is no mobile phone-based Uni-java release. But in the near future, Uni-java is bound to be a weapon of China Unicom. E. mrp domestic mobile cell phonegame which consists of Sky Network Technology Co., Ltd. [Hangzhou] developed a lightweight virtual platform MINIJ platform format, using standard written in ANSI C. Because it is self-developed, so in addition to the Internet, "Ranger cabin" space station and the stream has a bit of hand-size travel community to provide these applications and external Web download method, the current mobile games mrp civil official website has more detail www. mrp123.cn).

 A good business is not really the appreciation of the work and marketing tool received suffering from markets and telephone product of the strength is the key to victory, of course, low comprehensive

listing of G808 last year continue to allow me to appreciate the dance of the Samsung. It is the process and result of performing every operational instruction of

cell phone jammer .
The replacement phone of HTC product cycle is very fast, almost did not take long on a machine Huang. HTC family of Windows machines Huang HTC HD3, do not know yet listed. While Android is in fact

the front is not long, nothing more than the G3, the Hero. I think for many people, especially Chinese people do not want to play the machine to send messages to call you taking pictures, do not

buy the HTC. If you have a business role, the entertainment capital of the class you want to see the movie, send email, browse the World Wide Web, play a large 3D games. Then you consider that HTC

well. The most important thing is that the HTC machine hardware configuration is very good, and that old-fashioned Nokia is completely different. To show the detailed status of

cell phone jammer .
I saw a little boy says: Im gay, I use the M8 - and then immediately replied: do not lose our gay face on the cnbeta. Now is not a phone as small as possible. You go to Europe and the United

States to take a look at those famous models, they go on the street holding his hands a large mobile phone to send text messages there. Looks super Fan children. - Suitable for girls with Sharp a

lot of heads are not small, is said to hand a small little girls no way to single-handedly control the Sharp. I phone is very large, two hands to get maintained, BlackBerry texting should at least

use two hands. - On the trend of mobile phones the size of argument, I am more biased in favor of mobile phone now or bigger only decent. The system administrator can screen cell phone jammer .
Millet mobile marketing strategies and models dismantling. Presentation online site finishing. Introduction: the popularity of millet phone and the millet mobile phone marketing strategy is

inseparable from millet phones with what kind of marketing strategy?

 The trial run of production of cell phone jammer has been finished.
The nature of the system parameters and target system performance impact of airborne laser scanning system in the ranging process, the scanning angle is continuous change, Air to bring scattering scattering echo intensity is closely related to the scan angle, the echo power nadir Air band edge minimum SNR of the system and ranging accuracy and scanning angle, the flight strip 13 the edge of the ranging accuracy in the field of view angle is too large, have to exceed the system allow ranging accuracy range. On the other hand, vary greatly due to the reflectance of ground targets, the reflectivity of the target largely determines the echo intensity, so that it could cause some surface features not receive echo In particular, the band edge in the Air. It is during the technology discussion meeting of phone jammer .The customer can know the design or technology of mobile phone jammer  in advance
Therefore, for a practical system, the flying height and scan angle should be an allowed range, necessary for the flying height, scan angle, the system parameters and surface reflectance impact on system performance for in-depth theoretical study. 9.5 data classification and identification to obtain the raw data first has to go through gross error detection, and then create a ground-based data types, separation of non-ground data, based on customer requirements, non-ground data classification, such as building class data, and transmission line data, railroads data, simply use the distance data of the laser radar or laser reflection intensity information classification and identification of surface features is not satisfactory, we can not play the advanced nature of the laser radar technology. It is the design revise of phone jammer . 
 LVL 8 Dalian Economic and Technological Development Zone Laser Technology Development Co., Ltd. Dalian Economic and Technological Development Zone Lats Laser Technology Development Co., Ltd. Economic and Technological Development Zone JZC-G manual. Maintenance and annual inspection of the JZC 6.1 JZC of Maintenance maintenance period JZC maintenance period, such as instrument quality, free repair by the company responsible, and bear the shipping costs after repair, such as damage caused by improper, I am responsible for repairs, and collect the parts Gongben fee. Maintenance in the maintenance of more than maintenance of equipment problems, responsible for the repair will be based on the maintenance of price by us alone. The visual inspection should be done for the quality inspection of phone jammer .

The GPS mobile phone jammer owns the slow start circuit design.
As the profit margins of the conflict, the downstream distributors that upstream channel or production companies to earn more profits. There are channels of bargaining ability, regardless of the level of the channel members, as long as it is gradually expanding their own market power, more resources and profits from the upstream and downstream enterprises, resulting in a conflict. Compensate for price cuts, promotional costs and defective products and services is often a lot of conflict. Competitor analysis 1.3.1 Motorolas channel strategy for Motorolas channel has mainly taken the form of agency. Its development can be divided into several stages: before 1995, subject to the constraints of the market environment, Motorola sold by China Telecom. The power supply switch of GPS mobile phone jammer will generate the powerful current.
In 2002, Nokia strengthened at the retail level to compete with Motorolas comprehensive attempt selected five major chain stores in Shanghai and Guangdong, as a direct supply store. Across the agents directly to their supplier. In addition, in many provinces, Nokia in the seven major real estate agents outside a few strong regional distributors as a proxy to participate in the distribution of several models to compensate for the lack of agents across the country (Figure ). At the same time in the national underwriting way in some provinces and gradually try to regional underwriting. Nokia to enter the Chinese market than Motorolas much shorter time, so not much of a burden, distributors conditional direct construction of sales network. The effective shielding range of GPS mobile phone jammer is 5-10m.
Postel mainly rely on an agent on the market, such as long-term, Capitel Nokia store in major cities to establish system. Another feature of the Nokia channel construction is authorized service center functions with the store to play the store after-sales service advantages. From the characteristics of channel management, Nokias overall policy of the channel members are: multi-channel, few links, network refinement, price transparency. Nokia has recognized the phone as early as the end of 1997, will soon become a mature and transparent products, does not hold too many levels in the supply chain, develop and implementation of the Retail Management Plan is now store / concession counters plan. The rechargeable power supply of GPS mobile phone jammer is AC110-250V.The actual shielding range of mobile phone jammer is in the place

This add-on board is designed to provide a pair of balanced audio outputs for the High-Quality Stereo DAC (Digital to Analog Converter). Two 3-pin male XLR connectors are used for the new outputs and they can either replace or augment the existing unbalanced outputs without affecting their performance. Balanced audio is used in recording studios and on stage because of its improved noise immunity.

Picture of the project:

    

This is due to the fact that the signal is sent differentially (ie, as two signals 180° out of phase) and then converted to a single-ended voltage signal at the far end. If any noise is picked up in the cable, it affects the two out-of-phase signals equally so that when the signals are subsequently subtracted, most of the noise is eliminated.

Parts layout:

In addition, the DAC’s performance at the balanced outputs generally exceeds that of the unbalanced outputs, although only by a small margin. The signal-to-noise ratio, frequency response and channel separation are all better, although we measured a tiny bit more distortion from the balanced outputs. However, both levels are so low as to be almost negligible.

Circuit diagram:

Comparison chart:

 

Source : www.siliconchip.com