Archive for the ‘Coreelectronics’ Category

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Telephone Amplifier

April 7th, 2010 by Thomson | No Comments | Filed in Coreelectronics

A telephone amplifier enables more than one person to follow a telephone conversation. The unit described here, in common with all normal units of this type, requires no direct connection to the telephone. Instead, the special pick-up coil has a built-in rubber suction cap that enables it to be easily attached to the telephone base. This produces a very weak signal from the magnetic field radiated by an inductive component inside the telephone, but satisfactory results can be obtained if it is fed to low noise, high gain amplifier. It would of course be possible to use a much simpler circuit if a direct connection to the telephone were to be made, but this would make installation more difficult and it is ILLEGAL to make a direct connection to a Post Office telephone anyway.

Telephone amplifier Telephone Amplifier

The preamplifier stage of the unit is based on IC1 which is a low noise op amp having a FET input stage. This is used in the conventional inverting audio amplifier mode and the negative feedback network, R1, 4, sets the voltage gain at about 40dB. (100 times C11 reduces the gain slightly at high frequencies in order to obtain an improved signal to noise ratio.

C4 couples the output from the preamplifier to volume control, RV1, and from here the signal is coupled to the power amplifier by C5. The output stage uses the TBA820M, a class B amplifier which will give an output power of a few hundred milliwatts rms. The closed loop voltage gain of the device is determined by the value of R6, about 25dB. (180 times) with the specified value. This gives the required very high overall gain in conjunction with the preamplifier’s gain. C7, R7 and C8 are needed in order to maintain stability.

The quiescent current consumption of the unit is only about 5mA, but this rises to as much as 50mA or so at high volume levels. The best position for the pick-up coil on the telephone base (not the handset) can be located with a little experimentation.

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VMOS 10 Watt Amplifier

April 6th, 2010 by Thomson | No Comments | Filed in Coreelectronics

At first sight this circuit may seem to be a straightforward Class B design having an emitter follower, complementary output pair and Darlington Pair common emitter drive stage. However, the output devices are, in fact, complementary VMOS transistors used in the source follower mode (the FET equivalent of the emitter follower).

VMOS 10 watt amplifier free projects VMOS 10 Watt Amplifier

R1 and R2 are used to bias the unit to give the optimum quiescent output potential and they provide overall negative feedback, which improves the quality of reproduction. D1 and C4 are boot strapping components, enabling the gate drive voltage to Q3 to go above the positive supply potential, giving improved efficiency to the circuit. R3 is the main collector load for Q2 and PR1 is used to give a standing bias on the output transistors that gives a quiescent current consumption of about 25mA. The thermal compensation circuitry normally used is totally unnecessary in this circuit, since VMOS devices do not suffer from thermal runaway. In fact the quiescent bias current will drop slightly as the output devices heat up, but not sufficiently to give rise to significant crossover distortion.

C2 and C5 provide DC blocking at the input and output respectively, while C1 is a supply decoupling component. C3 gives a degree of high frequency attenuation and aids the stability of the circuit.

Although the current in the driver stage, only about 1mA, may seem to be totally inadequate, it is in fact more than sufficient since the VMOS devices have extremely high input impedances and consume no significant, input current. This is one of their main advantages over bipolar devices. One disadvantage in this particular application is lower efficiency due to the higher threshold voltages and on resistance of VMOS transistors in comparison to bipolar devices. However, the circuit will give an output of 10W rms using a supply voltrage of about 33V or so (with a current drain of up to about 600mA). An input of about 500mV rms is needed for maximum output.

Note: The output devices do not have internal zener protection diodes and the appropriate handling precautions should be taken.

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Cassette Preamplifier

April 3rd, 2010 by Thomson | No Comments | Filed in Coreelectronics

Used in conjunction with one of the cassette mechanisms currently available on the surplus market (or a mechanism removed from an old recorder or player) this preamplifier circuit makes an inexpensive but useful cassette player for use with a hi-fi system.

The output signal level from a cassette tape head is typically about 500 micro Volt or so at middle audio frequencies for a mono head and about half this level for a stereo type. The preamplifier must, therefore, provide a considerable amount of voltage gain in order to match this to a hi-fi amplifier, since these require a signal level about 1,000 times higher. It is also necessary for the preamplifier to provide equalization, because the output from a tape head rises at a rate of 6dB per octave. However at higher audio frequencies, tape heads are not very efficient and require a much less rolloff.

free electronics projects cassete preamplifier Cassette Preamplifier

Q1 and Q2 are used in a conventional two stage, direct coupled, common emitter amplifier and the frequency-selective negative feed-back through C3 and R4 provides the appropriate equalization. These also set the midband voltage gain of the input stage at about 46dB. With such a low input level it is obviously necessary to use low noise transistors (Such as the BC109C) in order to obtain good results. Running Q1 at a low collector Current, about 200uA, also helps.

Q3 is used as a low gain common emitter stage, which provides the additional amplification. R9 introduces negative feedback, which controls the voltage gain of Q3 and the specified value gives a gain of about 14dB. For a stereo unit R9 should be reduced to 390R in order to give increased gain, to compensate for the lower output of a stereo tape head.

When playing a Dolby B encoded cassette SVV1 can be closed; this gives a small degree of treble cut which provides a reasonably flat overall response.

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Scratch and Rumble Filter

March 18th, 2010 by Thomson | No Comments | Filed in Coreelectronics

This is a 12 dB per octave add-on scratch and rumble fill-r which can be connected into the ‘tape Monitor’ or some similar facility of the amplifier.

It is a conventional second order filter circuit having passive high pass filter formed by the series capacitance C3 and C4, plus the parallel resistance of R2 and R3 (the latter also being used to bias emitter follower transistor Q1). A passive filter of this type gives only a very slow initial roll off, and an ultimate attenuation rate of only 6 dB per octave. A bootstrapping resistor is therefore used to improve performance. Above the cut-off frequency, where the gain of the circuit would otherwise fall off somewhat, R1 has the effect of reinforcing the input signal. Well below the cut off frequency, losses through C4 result in the signal level at Q1 emitter being well below that at the junction of C3 and C4. This results in some of the signal at the junction of C3 and being tapped off through R1, with C3 and R1 effectively forming a second high pass filter network. This eliminates the sluts, initial roll off rate (in fact there is a small and insignificant peak of about 0.5dB above the cut off frequency) and speeds up the attenuation rate to a nominal 12dB per octave.

sceatch and rumble filter 300x141 Scratch and Rumble Filter

The low pass filter works in much the same way as the high pass one, except of course, the R and C filter elements have been transposed so as to give the correct filter action.

With the specified component values the rumble filter response falls below unity at approximately 45Hz, reaches the -6 d13 point just above 30Hz, and then falls away at a nominal 12dB per octave. The scratch filter response crosses the unity gain point at about 6k5Hz, reaches the -6dB point at approximately 10kHz, and then falls away at a nominal 12dB per octave.

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Simple amplifier

March 17th, 2010 by Thomson | No Comments | Filed in Coreelectronics

The term “amplifier” covers a very wide range, from a one transistor preamp to an ultra sophisticated high power hi-fi system. There is little doubt that the circuit shown here is very simple. The output is in the order 250mW – quite sufficient for most purposes and comparable to that of the average transistor radio. The distortion level is rather high, being about 5%.

The amplifier is also reasonably sensitive and will give full output with an input of about 50mV. Input impedance is about 50kR.

free electronic projects simple amplifier 300x227 Simple amplifier

The slider from the volume control is connected to the, base of Q1 via a DC blocking capacitor. Q1 is connected as a conventional common emitter amplifier with R2 provides the base bias and R3 acting as the collector load. This stage is directly connected to the second transistor which is a PNP type. In this way the current passing through Q1 provides the bias for the second transistor. The output of the second transistor is connected directly to the speech coil of the loudspeaker. This is not normally good practice since the standing current in the output transistor continually biases the coil either slightly in or out from its usual operating point. However if a large speaker is used, as it should be, this has very little effect and, since we are not aiming at hi-fi, it does not matter.

The tone control comprises C2 and RV2 which are connected between the collector and base of Q1 At high resistance settings RV2 has little effect but on minimum settings the 100nF feeds back the high frequencies out of phase, thus cancelling them.

For this circuit to work properly, R3 must be selected with great care. The value shown here of 39 ohms is a typical one and, although it may be used for initial setting up to ensure the circuit is operating, the value should be found by experiment. If it is too low there will be severe distortion at higher volume settings. If it is too high the current drain will be excessive even though the quality of reproduction will be good.

It is very important that Q2 is fitted with a heat sink as it will get very not.

The speaker impedance is not all that critical and in the prototype speakers with an impedance as low as 8 ohms and as high as 80 ohms all worked well, although changing the speaker impedance will also necessitate a change in the value of R3.

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Treble booster

March 13th, 2010 by Thomson | No Comments | Filed in Coreelectronics

A treble booster circuit can be used with an electric guitar (and also electronic instruments) to boost the higher order harmonics and give a more brilliant sound. A circuit of this type gives a fairly flat response at bass and most middle audio frequencies, with the upper-middle and lower treble frequencies being given a substantial amount of boost. It is normal to use only a modest amount of emphasis to the upper treble in order to give good stability and a low noise level, and this also prevents the output from sounding too harsh. The frequency response is shown in the accompanying graph.

treble booster free circuit diagram 300x168 Treble booster

The circuit is basically an op-amp used in the non-inverting amplifier mode. The non-inverting input is biased by R4 and R5 via a decoupling network which is comprised of R3 and C3. C4 and C5 give DC blocking at the input and output respectively. With SW1 open there is virtually 100% negative feedback through R1, R2 and C1, giving the circuit unit gain and a flat response. Closing SW1 brings C2 into circuit, and this de-couples some of the feedback through R1 and R2 at frequencies of more than a few hundred Hz, giving the required rising response. Feedback through C1 at high treble frequencies causes the response to fall away above about 5k5Hz, and prevents the very high frequency harmonics from being excessively emphasized.

treble booster frequency response curve 300x264 Treble booster

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RIAA stereo preamplifier

March 13th, 2010 by Thomson | No Comments | Filed in Coreelectronics

Records are cut with a frequency response such that when they are replayed with a magnetic pickup and a preamplifier with RIAA equalization (Recording Industry Association of America) the reproduced sound will be as similar to the original as possible.

The disc is cut at constant amplitude, except from 500Hz to 2120Hz where it is cut at constant velocity. When this disc is replayed with a magnetic pickup, the relative output voltage rises with frequency, due to the fact that the magnetically generated voltage is proportional to the velocity of the stylus as it moves sideways in the groove. To restore the original sound quality, a preamplifier with a frequency response that, gives decreasing output with increasing frequency is required. This response curve is known as the RIAA equalization and it is tailored accurately to fit the cutting and replay processes. The signal level from a magnetic pickup is low, generally 20mVpp and so a low noise pre- amplifier is needed.

RIAA sterio preamplifier left RIAA stereo preamplifier

RIAA sterio preamplifier right 300x181 RIAA stereo preamplifier

The circuit shows a realization of this requirement. The low noise amplifier is the LM381 -made by National Semiconductors. A DC bias control is included (RV1, RV2), and the feedback components generate the RIAA curve. Use screened cable for the wiring to the pickup, keep the circuit away from transformers (and the pickup and its wiring) and connect all the earths together, near to the IC.

RIAA sterio preamplifier graph 300x263 RIAA stereo preamplifier

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Free download manager

March 4th, 2010 by Thomson | No Comments | Filed in Coreelectronics

free down load manager Free download managerDownload manager software can do wonders for people who wish to download a lot of data and files. The main problem with downloading large files is that, there is a chance for the internet connection to break while downloading. If you are using a download manager then the file download will resume when the connection comes back. FDM (Free Download Manager) is one such useful software utility using which you can manage all your downloads. As a download manager FDM is an easy to use tool. FDM is a powerful download accelerator which is free to download at the same time. No need to worry about the safety of FDM, it is hundred percent safe. Since it is open source software, GPL license governs its distribution.

Features of FDM

Unbeatable download speed:

FDM uses the technique of splitting the file being downloaded into sections. After the file has been sliced into different sections, all sections are downloaded at the same time. This increases the download speed up to 600 percentages.

Broken download management:

Oops! Internet connection failed. No need to worry about such a scenario. With FDM broken downloads are automatically resumed. So just start the download and forget it.

Support for protocols:

Files from any remote server can be downloaded using HTTP, HTTPS and FTP. BitTorrent protocol can also be used for file downloads.

Video download support:

Download your favourite videos from your favourite video sites like Google video, YouTube etc. The downloaded videos can be saved in .flv format, or can be converted into other commonly used formats.

How to get FDM?

Follow the below link to download FDM

DOWNLOAD FDM

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Intel atom Z500 price and Intel atom Z500 specifications

February 1st, 2010 by Thomson | No Comments | Filed in Coreelectronics

Intel atom Z500 price and specifications Intel atom Z500 price and Intel atom Z500 specificationsIntel atom Z500 processors are very small processors with a dimension of 13X14 mm. Intel atom Z500 consist of nearly 47 million transistors. Number of transistors that constitute Intel atom Z500 processor is more than the number of transistors used to build up Intel Pentium 4 processor. Level-1 cache of Intel atom Z500 processor is about 56KB. Intel atom Z500 has a level-2 cache of about 512KB. The bus used in association with Intel atom Z500 processor is the same as used along with Intel Pentium 4. Bus frequency is about 400/533 MHz.

Intel atom Z500 Specifications:

Intel atom Z500 has only one core.

Intel atom Z500 has two threads.

2 GHz is the base frequency of Intel 500 processor.

Intel atom Z500 is a 32 bit microprocessor.

Intel atom Z500 has 512 KB of L2 cache.

FSB speed of Intel atom Z500 is about 533 MHz.

Intel atom Z500 Price:

Price of Intel atom Z500 is about 45 dollars. ie 2,083.12 INR

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Intel core 2 duo E6700 Price and core 2 duo E6700 Specifications

January 30th, 2010 by Thomson | No Comments | Filed in Coreelectronics

intel core two duo processor Intel core 2 duo E6700 Price and core 2 duo E6700 SpecificationsAmong all processors now available in the market Intel core 2 duo E6700 is the most cost efficient processor. Since miniaturization is the order of the day processors that can deliver the maximum with the minimum power is preferred by the industry. If the power consumption of a processor is less heat generated by it will also be less. From this point of view Intel core 2 duo E6700 can be given the highest mark. Intel core 2 duo E6700 consume less power compared to other processors available in the market. This low power consumption feature of Intel core 2 duo E6700 points to the fact that the heat produced by Intel core 2 duo E6700 is also less. Intel core 2 duo E6700 is not only a cool processor, it can work without making much noise. All the above mentioned features of Intel core 2 duo E6700 makes it suitable to be used in small PC designs.

Features of Intel core 2 duo E6700:

Intel core 2 duo E6700 is a 64 bit processor.
Clock speed of Intel core 2 duo E6700 processor is 2.66GHz.
Intel core 2 duo E6700 ultra performing processor has a bus speed of 1066MHz.

Price of Intel core 2 duo E6700:

Price of Intel core 2 duo E6700 is 397.95 dollars. ie 18,413.15 Rupees.

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Electromagnetic spectrum

January 29th, 2010 by Thomson | No Comments | Filed in Coreelectronics

The information signal should be converted into electronic signals, when free space is the channel. Such signal consists of both electric and magnetic fields. The so-called electromagnetic signals are also referred to as radio frequency (RF) waves.
RF waves oscillate i.e., amplitude of the electric and magnetic fields vary at the specific rate. These oscillations may occur at a very low frequency or at an extremely high frequency. This entire range of frequency is the electromagnetic spectrum. Electromagnetic radiation has an electric field and magnetic field which oscillate in phase perpendicular to each other and to the direction of propagation. Radio frequency band is the frequency or the rate of oscillation within the range of about 3Hz to 300GHz.

electromagnetic spectrum Electromagnetic spectrum

The frequency spectrum extends from subsonic frequencies (a few hertz) to cosmic rays (1022Hz). The International Radio Consultative Committee (CCIR) bands are given below.

Extremely low frequency (ELF) :

ELF range varies from 30Hz to 300Hz and includes ac power signals and low frequency telemetry signals.

Voice frequencies (VFs) :

VF range varies from 300Hz to 3000Hz. Standard telephone channels has 300Hz to 3000Hz bandwidth.

Very low frequency(VLF) :

VLF range varies from 3 KHz to 30 KHz, which includes the upper end of human hearing range. They are used in sub-marine applications.

Low frequency (LF):

LF range varies from 30 KHz to 300 KHz and is used in marine and aeronautical navigation.

Medium frequency(MF):

MF range varies from 300 KHz to 3 MHz and is used for commercial AM broadcasting (535 KHz to 1605 KHz).

High frequency(HF):

HF ranges vary from 3 MHz to 30 MHz and are called short waves. Most of the two-way communications use this range. Amateur radio and citizen band radio also use signals in this range.

Very high frequency (VHF):

VHF range is from 30 MHz to 300 MHz, these are used for mobile, radio, marine, aeronautical communications, commercial FM broadcasting (88 MHz to 108 MHz ) and commercial TV broadcasting (54 MHz to 216 MHz)- channels (2-13).

Ultra high frequency(UHF):

UHF range is from 300 MHz to 3 GHz. It is used for commercial TV broadcasting of channels 14-83, land mobile communication, cellular phones military services, certain radar and navigation systems, microwave and satellite radio systems. Frequencies above 1 GHz are microwaves.

Super high frequency(SHF):

SHF range varies from 3 GHz to 30 GHz and is used in microwave and satellite communication.

Extremely high frequency (EHF):

EHF range varies from 30 GHz to 300 GHz.

Elements of communication system

January 29th, 2010 by Thomson | No Comments | Filed in Coreelectronics

Communication:
It is the process of exchanging information from one position to the other. Electronic communication is the transmission, reception and processing of information between two or more locations using electronic circuits.
Elements of communication:

elements of communication system Elements of communication system

Information signal is given to the transmitter which then transmits the message over the medium to the receiver. Noise gets added up to the message in the channel. It degrades the transmitted information.
Transmitter:
It has a collection of electronic components and circuits which are designed to convert information signal into electronic signals compatible with the medium.
Receiver:
It accepts the transmitted message and converts it back into an understandable form.
Communication channel:
It is the medium by which electronic signal is sent from one location to the other.
Signals which have to be transmitted are converted into electric and magnetic fields that propagate readily over long distances. Also, the medium attenuates the signal which results in the signal degradation. Finally the amplitude of the signal received will be much lower than original signal. Hence, the amplification of the signal should be done both at the transmitter and the receiver.
Noise:
It is the unwanted electrical energy which gets added up with the information signal at the channel.
E.g.: Noise due to lightening i.e., from the atmosphere, Internal noise due to internal agitation of atoms inside the components.
Due to noise message may get completely missed or misinterpreted.

Free download paragon system backup 2010 free serial key

January 20th, 2010 by Thomson | 1 Comment | Filed in Coreelectronics

It is a fact that you cannot fully rely on your personal computer. There is a chance for all the electronic devices to crash at any time. What will you do if your system crashes? No need to worry about the loss of data anymore if you have paragon system backup 2010. The new paragon system backup 2010 is a really useful tool with which you can take backup of all the critical data and even the operating system. With the help of this recovery tools like paragon system backup 2010 you can have a backup of your critical information during the time of a system crash.

paragon systembackup 2010 free serialkey free download Free download paragon system backup 2010 free serial key

Features of the new paragon system backup 2010 will help you to save your data from being lost. Storage of backup images can be managed by the create new storage wizard. With the help of the new paragon system backup 2010 you can take backups and store on external drives. Paragon system backup 2010 have another feature called smart backup. The smart backup feature of the new paragon system backup 2010 will take a backup in the background without much loss in the performance. Actual cost of paragon system backup 2010 is about 30 dollars. But there is a chance for you get the same for free.

How to get paragon system backup 2010 for free?

  1. Goto the promotional webpage page at http://www.paragon-software.com/registration/sbrc.html
  2. Fill the details in the form shown on the resulting web page.
  3. Paragon System Backup 2010 RC Product Key and Serial Number will be emailed to you.
  4. Download Paragon System Backup 2010 by following the link – http://dl.paragon-software.com/beta/Paragon_SystemBackup2010-rc.exe
  5. Copy of Paragon System Backup 2010 can be registered with the information provided in the mail.

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Buy the new Panasonic VIERA TH-P54Z1N

January 8th, 2010 by Thomson | No Comments | Filed in Coreelectronics

Buy the new Panasonic VIERA TH-P54Z1N

panasonic viera z series VIERA TH P54Z1N Buy the new Panasonic VIERA TH P54Z1N

The Z series plasma TV of Panasonic is an ultra thin model. It is a Full-HD NeoPDP plasma TV model. Picture quality of this model is excellent. Networking capabilities of the new Viera TH-P54Z1N plasma TV is great.

Features of Panasonic Viera TH-P54Z1N:

The new Panasonic Viera TH-P54Z1N has a sub-field drive of about 600Hz.

Display of the new Panasonic Viera TH-P54Z1N plasma TV is THX certified.

Panasonic Viera TH-P54Z1N has a very high contrast ratio of about 2,000,000:1. This high contrast ration gives infinite black.

Networking capabilities of the new Panasonic Viera TH-P54Z1N is useful and quiet good.

You can view images by using the new Panasonic Viera TH-P54Z1N.

Price of Panasonic Viera TH-P54Z1N:

Price of the new Panasonic Viera TH-P54Z1N is about Rs. 328274.0

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AMD Phenom II X4 955 BE features

January 7th, 2010 by Thomson | No Comments | Filed in Coreelectronics

AMD Phenom II X4 955 BE features

AMD phenom II X4 955 AMD Phenom II X4 955 BE features

AMD Phenom II X4 955 BE, where BE stands for Black Edition, is AMD’s fastest processor they have released till now. Default clock speed of AMD Phenom II X4 955 processor is 3.2 GHz. Socket AM3 is supported by the new AMD Phenom II X4 955 in addition to AM2+ motherboards.

Memory support of AMD Phenom II X4 955

Both DDR2 and DDR3 memories are compatible with the new AMD Phenom II X4 955 processor.

Over clocking AMD Phenom II X4 955

The new AMD Phenom II X4 955 processor has an unlocked multiplier. The presence of this unlocked multiplier helps in unlocking the new AMD Phenom II X4 955.

AMD is competing with Intel’s Core 2 Quad Q9590.

Price of AMD Phenom II X4 955

AMD Phenom II X4 955 can be bought for 217.99 Euro. Indian customers would like to know the amount in INR. Price of AMD Phenom II X4 955 is 14,266.62 Rupees.

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