Selasa, 14 Februari 2012

BTL Amplifier

Mini series of BTL Amplifier with Digital Volume Control above is pretty simple and pretty to make room for a small amplifier or to headphones. May be useful and can provide ideas to make digital amplifier with volume control.

Amplifier with digital volume control can be made ​​predictably simple because the article Mini BTL Amplifier with Digital Volume Control This series is made only by an IC TDA8551. Mini series of BTL Amplifier with Digital Volume Control is a kind of BTL amplifier with power 1Watt. Volume regulation technique in this series have been provided with a pin control lines are controlled by an input voltage VCC and GND. Mini series of BTL Amplifier with Digital Volume Control also features a mute selector, standby and operating.
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Senin, 13 Februari 2012

regulator IC

Rectifier circuit is good enough if the voltage ripple is small, but there are stability issues. If PLN voltage up / down, then the output voltage will also rise / fall. As rectifier circuit above, if the greater flow of dc discharge voltage was also decreased. For some applications this voltage change is quite annoying, so it requires the active components that can regulate the output voltage becomes stable.

Voltage regulators voltage serves as a filter to suit. Therefore, it is usually in a series of power supply the voltage regulator IC is always used for stabilizing the voltage out put.

The following arrangement of the regulator IC legs.

For example, 7805 is a voltage regulator to get a +5 volt, +12 volt voltage regulator 7812 and beyond. While the 79XX series is the 7905 and 7912 such that a row is a voltage regulator -5 and -12 volts.

Apart from a fixed voltage regulators have a voltage regulator IC is also adjustable. The principle is the same as the OP-amp regulator packaged in a single IC for regulators such as LM317 and LM337 variable positive to negative variable regulator. The difference between resistor R1 and R2 are outside the IC, so the output voltage can be set via external resistors.

The simplest regulator circuit shown in figure 6. In this circuit, zener breakdown work in the area, thereby producing an output voltage equal to or zener voltage Vout = Vi. But this series is only useful if the load current not exceeding 50mA.

The principle of the power supply circuit is called a shunt regulator, one of his trademark is the component parallel to the load regulator. Another characteristic of the shunt regulator is susceptible to short-circuit. Note if Vout connected short (short-circuit) then the current is fixed I = Vin/R1. Besides the shunt regulator, there is also called a series regulator. The main principle of such series regulator circuit in Figure 7 below. In this circuit the output voltage is:

Vout = VZ + VBE

VBE is the base-emitter voltage of transistor Q1 which is between 0.2 - 0.7 volts depending on the type of transistor used. By ignoring the IB currents flowing in the transistor base, R2 can be calculated of the prisoners are required are:

R2 = (Vin - Vi) / Iz

Iz is the minimum flow required by the zener diode breakdown voltage zener to achieve it. Large currents can be known from the datasheet that the amount of approximately 20 mA.

If needed supply a larger current, base current IB of the calculations in the above circuit can not be ignored anymore. Where as is known, a large flow of IC will be directly proportional to the flow defined by IB or IC = Bib. For this purpose, the transistor Q1 is used can be replaced with a Darlington transistor usually has a value of b is large enough. With a Darlington transistor, the current small base current can produce a larger IC.

Techniques that better regulation is to use the Op-Amp to drive a transistor Q, as shown in figure 8 circuit. Zener diodes are not here to give direct feedback to the transistor Q, but as a reference voltage for IC1 Op-Amp. Pin negative feedback on the Op-amp is an excerpt from the voltage regulator out, namely:

Vin (-) = (R2 / (R1 + R2)) Vout

If the voltage Vout ascending out, the voltage Vin (-) will also be upward until the voltage is equal to the reference voltage Vi. And vice versa if the voltage Vout decreases exit, such as the supply current to the load increases, the op-amp will maintain stability in a given reference point Vi IB flows to the transistor Q1. So at all times maintain the stability of Op-amp:

Vin (-) = ½

By ignoring the voltage VBE of transistors Q1 and mensubsitusi formula (11) into the formula (10) is obtained by the mathematical relationship:

Vout = ((R1 + R2) / R2) ½

In this circuit the output voltage can be set to adjust the R1 and R2.

Now it should no longer have to laboriously search for op-amps, transistors and other components to realize the regulator circuit as above. Because these circuits are packed into a fixed voltage regulator IC. Are now widely known as the 78XX series parts stayed positive voltage regulator and the 79XX series is a negative regulator for a fixed voltage. In fact, these components are usually already equipped with current limiting (current limiter) and also the limiting temperature (thermal shutdown). This component is only three pins, and by adding some components alone can be a power supply circuit that was a good regulation.

It's just note that the IC regulator circuit can work, the input voltage must be greater than the output voltage regulators. Usually the difference in voltage Vin to Vout recommended in the datasheet component. Use of heat sink (aluminum coolers) is recommended if these components are used for supply large currents. In the datasheet, this component can pass through the flow reaches a maximum of 1 A.
READ MORE - regulator IC

Parts of the tuner

Parts of the tuner:
A. The selection of channels (selection transmitting stations)
Tuner blocks to choose the wave transmitter to be received, including channel 2 to channel 12 (47-230 MHz) in VHF and each channel has a width of the frequency of 7 MHz. Circuit tuning can be chosen so that resonance the frequency channel of your choice.
In the tuner block are RF amplifier, Mixer and Oscillator. RF amplifier to choose the transmitter to be received, and then supplied to the mixer, oscillator generating a frequency of certain magnitude to the comparison frequency to be received RF amplifier is then supplied to the mixer and the filter eventually produce a new frequency is out of the 38.9 MHz is the carrier frequency images therein there is a synchronization signal and 33.4 MHz is the frequency of sound carrier and the second frequency is forwarded to the video amplifier IF.

2. Amplifier of high frequency (HF Amplifier)
Prior to the series mixing (mixing) wave tv amplified by the amplifier HF. Because the ratio S / N (the comparison signal / noise) at the receiver a color TV set by amplifier HF, then strengthening HF should be able to produce amplifier (gain) is great. Also requires a distortion of small even when a wave of TV a large input. Then the required voltage AGC (Automatic Gain Control / control amplifier automatically) to the amplifier HF was mounted a series of neutralization, the amplifier HF ​​to prevent parasitic oscillation occurs. Characteristic frequency response of the amplifier HF in the field of frequency channel receiver, must be equal as possible and the difference reinforcement between the canals received should be as small as possible.

3. Mixer (Mixer)
Wave TV received TV mixed with the output local oscillator using a mixer (mixer) and converted into a signal IF (Intermediate) images that have a frequency equal to the difference in both frequency earlier. The carrier frequency signal IF the image is 38.9 MHz and the carrier frequency of the sound signal is 33.4 MHz.

Canal No. 3:
Frequency Osc
38.9 MHz
33.4 MHz

55.25 60.75 95.15 MHz

4. Local oscillator
Frequency mixer (Frequency local) generated by local oscillator, and supplied to the mixer (Mixer). Frequency can be changed depending on the channel selected recipients.
As the local oscillator is usually used oscillator Colpitts because of the nature of its stability and simple structure his series. There are two ways to choose the frequency of the first local by changing the coil resonance and the second by controlling the bias voltage of the diode capacitance is variable.
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Operational Amplifier

Operational Amplifier (Op-Amp) is a differential amplifier into a high trailer directly.

Op Amp is a circuit that generates the output voltage V0, which is the result of the strengthening of the difference in the two input voltages V1 and V2.

Op-Amp Characteristics
Acquisition of infinite voltage.
Bandwidth is not infinite.
Enter an infinite impedance.
Out zero impedance.
Complete balance sheet, which is zero if the output voltages at the same time there are two input terminals.
Characteristics are not changed by temperature.
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DC power

The PS10 power supply provide +15 Volt and -15 Volt regulated DC power at up to 250 mA of current per output. The two outputs have a common ground connection. The outputs are short circuit proof. A thermal protection turns the outputs off when the circuit is overheated. A low input to output stray capacitance guaranties a low AC leakage current and makes the PS10 well suited in applications where low hum and noise is important, such as low level pre-amplifiers and audio applications. The PS10 uses a dual winding AC transformer. A Light Emitting Diode at each output indicates proper output voltage.

Output voltage: . . . . . . . . . . . . . +/- 15 Volt, +/- 5%
Max continuous output current:. . . . . . 250 mA each channel
Output short circuit current: . . . . . . 1.5A, typical.
Nominal input voltage:. . . . . . . . . . 115/230VAC, 50/60 Hz
Output voltage ripple:. . . . . . . . . . less than 10mV, @ 60 Hz, 250 mA load
Output voltage regulation:. . . . . . . . better then 10 mV
Input to Output capacitance:. . . . . . . 50 pF Max.
Dimensions (L X W X H): . . . . . . . . . 4.3" X 2.0" X 1.5"
Ordering Information

PS10-B Bare board with manual
PS10-K Kit with manual and all parts
PS10-A Fully assembled and tested
PS10-M Manual only
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Power supply 5 volts 5 A with a pass transistor

Power supply 5 volts 5 A with a pass transistor

By using 7805 components, it can easily be made a series of excellent power supply output voltage regulation. However, the component 7805 can only be effectively distribute the current to 1 A only. 5 volt power supply is generally used to distribute many different applications, so it sometimes is not enough supply current 1A.

In this article presents the design electroniclab regulated 5 volt power supply that can supply enough current to 5 A, at least it is ever tested in the workshop electroniclab. Actually, this circuit could distribute up to 10 A or even more if the reader know tips to modify it.

The core of this circuit certainly is a basic circuit with a 7805 5 volt regulator. The difference is, the series pass transistor is added to the circuit consisting of transistors Q1 and 2 pieces of resistors R1 and R2. 7805 components in control regulates the output voltage, and a series pass transistor is essential to drain the remaining current to the load RL.

The transistors used are the MJ2955 PNP transistor. Transistor is known as silicon bipolar power transistors are often found in the market. Readers can in principle be replace it with other bipolar power transistor, provided with similar characteristics. From the datasheet, it is known that the category of transistor power transistor collector current Ic as 15A can be achieved with power dissipation that can reach 115 watts. Of course in designing a series of maximum limits should be aware of this, so it does not exceed the optimum can be achieved.

Note the series of images above. In the closed-loop current through the resistor R1, R2 and the emitter-base transistor Q1, can be formulated mathematically:

I1R1 = IeR2 + VBE (on) â € | â € | â € | (1)

For silicon transistors usually VBE (on) = 0.7 volts, the base-emitter voltage causes transistor starts working (ON). This voltage is known from the datasheet VBE (on) this can vary between 0.6 ~ 1.4 volts depending on which of the current Ic through the transistor. But for the simplification of the calculation, we set the course VBE (on) = 0.7 volts.

I1 is the current through the 7805 onwards will supply the load RL. With this series we will be setting a large current through 7805, for example if you set current I1 = 500 mA. So how to supply current to the load RL to 5A? Of course the rest would flow MJ2955 is passed through the transistor. Of formula (1) it is understandable that the current passing through R2 Ie will begin to flow only when the voltage across the resistor R1 flops greater than VBE (on) or mathematically:

I1R1> = VBE (on) â € |. (2)

If the magnitude of the above disubsitusikan to formula (2) of the R1 can be calculated that is required is:

R1 = VBE (0n) / I1 = 0.7/0.5 = 1.4 Ohm

How to set a large current I1 = 500 mA, may be whether more or less. If we trace back a little, we first want to make a power supply with Io = 5 A. In the above circuit, Io = Ic + IOA € ™. If we consider the IOA € ™ is quite small compared to Ic, then Ic = Io can be written. Of transistor known theory that Ic = Hfe Ib. MJ2955 datasheet from Hfe big unknown is 20 ~ 70. You can search for a transistor with Hfe = 50. If this is used, then that must be supplied base current is Ib = Ic / Hfe = 5/50 = 100 mA. With this calculation is not wrong if it is assumed to be masksimum current of 500 mA through R1. Because it will supply enough base current Ib (at 100 mA) required to supply current Ic transistor Q1 to 5 A.

Great resistance R2 can be calculated from Vin to Vout loop through the transistor Q1 is defined by:

Vin = IeR2 + VCE (on) + Vout â € |. (3)

Vin is the voltage output of the rectifier circuit made ​​of a series transformer, diode bridge and capacitor elco. If for example Vin = 7 volts and the output voltage Vout = 5 volts, then the formula (3) can ditullis be:

+ 7 = IeR2 VCE (on) + 5


IeR2 + VCE (on) = 2 volts â € | .. (4)

This is the line or lines of work load transistor Q1. Assuming that Ie = Ic = 5 A and VCE (on) = 0 volts (ideal) when the transistor Q1 is working (ON), then it can be calculated of R2 = 2/5 = 0.4 Ohm. Finish â € |? of course not, because it must be specified wattage of the resistor is large. Of the general formula P = I2R power dissipation can be calculated on the resistor R2 is P = 52 (0.4) = 10 watts (minimum), then used the 0.4 Ohm 20 watt resistor to be safe.

Thus the sequence of this power supply design. Of course this design can be modified as needed. For tips last, With such a large current, temperature resistors and transistors will be so hot. Highly recommended to use a heatsink for the transistor Q1 and also R2 resitor. 7805 component should not require a heatsink, because the current through this component is relatively small. Elco capacitor C1 is the recommendation of the 7805 datasheet for more stable output voltage.

To the needs of larger currents, transistor Q1 can be replaced with a Darlington transistor, or a way to pass transistor cascade circuit into 2 or 3 level. In principle, the above calculations can also be applied to other power supply circuit design such as 12 volts or 24 volts.
READ MORE - Power supply 5 volts 5 A with a pass transistor

Minggu, 12 Februari 2012

DIAC structure

When viewed the structure as shown below, not including DIAC thyristor family, but his principle of making it is classified as a thyristor. DIAC is made with structures similar to the PNP transistor. N layer on a transistor made so thin that electrons can easily penetrate across this layer. While at DIAC, N layer is made thick enough so that the electron is quite difficult to penetrate. DIAC structure which can thus also be viewed as two PN diode and the NP, resulting in some literature DIAC classified as a diode.

Difficult to be passed by two-way flow, DIAC was intended for this purpose. Only with a specific breakdown voltage before DIAC can conduct current. Current course can be delivered back and forth from the anode to the cathode and vice versa. DIAC same characteristic curve as TRIAC, but that just need to know is how its breakdown voltage.
Symbol of the DIAC is as shown in the image above. DIAC is generally used as a trigger ON the TRIAC to a specific input voltage is relatively high. An example is the following lamp dimmer applications in the figure below:

If it is known in the circuit TRIAC IGT of 10 mA and above the VGT = 0.7 volts. And note also that is used is a DIAC with VBO = 20 V, the TRIAC will be calculated on the ON voltage:
V = IGT (R) + VBO + VGT = 120.7 V

On a dimmer circuit, the resistor R is usually replaced with series resistors and potentiometers. Here with a series capacitor C R is used to shift the phase voltage VAC.
READ MORE - DIAC structure

Null Modem

Null Modem configurations are used to connect two DTE with a wiring diagram that can be seen in the image below. In this case it only takes three wires between the DTE, which is to TxD, RxD and Gnd. The way it works is how to make the computer into thinking that the computer communicates with the modem (DCE) rather than with other computers.

In the picture above shows that the foot DTR (Data Terminal Ready) is connected to the DSR (Data Set Ready) and also to the CD (Carrier Detect) on each computer, so that when the DTR signal is activated then DSR and CD signals also active (Modem concepts Virtual Modem or pseudo). Because the computer in this case sending data at the same speed, the flow control (flow control) is not required so that the RTS (Request To Send) and CTS (Clear to Send) on each computer connected to each other.

Data transmission in RS232
The RS-232 communication with PC is asynchronous communication. Where clocknya signal is not sent along with the data. Each data synchronized using the internal clock on each side. Figure 2.6 Format of transmission of the RS232 Data byte transmitted in the above format is 8 bits, before the data is transmitted it will be preceded by a start bit to logic 0 (0 volts), then 8 bits of data and is terminated by a stop bit to logic 1 ( 5 Volt).

Advantages of Using Serial Communications
Serial communications interface offers several advantages compared with parallel communication, including:

• Cables for serial communication can be longer than parallel.
The data in the serial communication is sent to logic '1 'as the voltage of -3 s / d and -25 volts for logic '0' as the voltage of +3 s / d +25 volts, thus the voltage in serial communication has a maximum voltage swing of 50 volts, while the parallel communication is only 5 volts. This causes disruption in the wiring length is more easily overcome than the parallel.

• The number of serial cable less.
Two sets of a remote computer with only three cables to null modem configuration, ie, TxD (send channel), RxD (receive channel) and the Ground, but if you use parallel communication there will be twenty to twenty-five wires.

• Serial communications can use the free air as the transmission medium.
In the serial communication is transmitted one bit at a time so that when the transmission using a media-free air (free space) then the receiver section will not appear difficult to reconstruct the bits of bits transmitted.

• Serial communications can be applied to communicate with the microcontroller.
It only takes two main pin TxD and RxD (outside the reference ground).
READ MORE - Null Modem


RS232 standard set by the Electronic Industry Association and Telecommunications Industry Association in 1962. His full name is EIA/TIA-232 Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange. Although his name is quite long but this standard is only concerned with data communication between computer equipment computer peripherals. There are two main things that set the standard RS232, among other things:

• The shape and signal voltage levels are used.

RS232 built in 1962, long before the popular TTL IC, therefore the voltage levels specified for RS232 nothing to do with TTL voltage levels, it can even be said that different. Here's the difference between RS232 and TTL voltage levels:

Determination of types of signals and connectors that are used, as well as the arrangement of the signal at the legs of the connector. Some parameters are defined EIA (Electronics Industry Association •), among others:

• A 'space' (logic 0) voltage between +3 s / d +25 volt
• A 'sign' (logic 1) voltage between -3 s / d -25 volt
• Local voltage between +3 s / d -3 volts is not defined
• open circuit voltage should not exceed 25 volts (with reference to ground)
• short circuit current of the circuit should not exceed 500 mA.

A driver (drivers) should be able to handle this current without damage. In addition to describing the voltage levels as discussed above, standard RS232 determine the types of signals are used to set the exchange of information between the DTE and DCE, are all there are 24 types of common signals but that is only 9 types of signals. Connectors used were determined in a standard RS232, for a complete signal used DB25 connectors, while the DB9 connector can only be used for commonly used signal 9.


PNPN structure

Thyristor stems from the Greek word meaning 'door'. Perhaps so named because of the nature of this component is similar to that door can be opened and closed to pass an electric current. There are several components that include, among others thyristor PUT (programmable uni-junction transistor), UJT (uni-junction transistor), GTO (gate turn off switch), photo SCR and so on. But on this occasion, which will point out the components of the thyristor known as SCR (silicon controlled rectifier), TRIAC and DIAC. Readers can listen to more clearly how the working principles and their application.
thyristor structure
The main characteristics of a thyristor is a component made of silicon semiconductor material. Although the material is the same, but its PN junction structure is more complex than a bipolar or MOS transistor. Thyristor component is more used as a switch (switch) rather than as an amplifier as well as current or voltage transistor.

Basic structure of the thyristor is a four layer PNPN structure as shown in the figure above a. If sorted, this structure can be seen as two PNP and NPN junction structure are connected in the middle as shown above b. This is nothing but the two PNP and NPN transistors are connected to each collector and base. If visualized as transistors Q1 and Q2, then the thyristor structure can be displayed as shown below.

Seen here is connected to the collector of transistor Q1 base of transistor Q2 and the collector of transistor Q2 is connected opposite the base of transistor Q1. Such a transistor circuit indicate a strengthening of the current loop in the middle. Where b is known that Ic = Ib, the collector current is the strengthening of the current base.
If for example there is a current of Ib flowing to the base of transistor Q2, then there will be current Ic flowing in the collector of Q2. This collector current is the base current Ib to the transistor Q1, so it would appear on the strengthening of the current collector of the transistor Q1. Tdak transistor Q1 collector current is the current base of another transistor Q2. So forth so that the longer the PN connection of the thyristor is in the middle will shrink and disappear. Left is the P and N layers on the outside.
If this condition is reached, then such a structure is the structure of the swordfish another PN diode (anode-cathode) are already known. At such a time, called the thyristor is ON and the current can flow from the anode to the cathode such as a diode.

What if we give in this thyristor dc lamp load and rated supply voltage from zero to a certain voltage as shown above. What happens to light when a voltage is increased from zero. Yes yes, of course, the lights will remain off for the middle layer of the existing NP will get a reverse-biased (diode theory). At this time called the thyristor is turned OFF because no current can flow, or very small. Current can not flow through a reverse-bias voltage that causes certain connections and missing NP is saturated. This voltage is called breakdown voltage and current at the time it began to flow through diode thyristor as large. At this voltage thyristor breakover voltage VBO called.
READ MORE - PNPN structure


The MOS-FET transistors on the heat sink may be tested while they are not yet connected to the transformer and the control unit. First we touch with one hand the source connections of the transistors and with the other the gate connections. This will discharge the gates. Now the source / drain connections must behave like a diode, which we can test with an ohm meter. For the next test we connect a car lamp between the drain connections of the transistors and the positive pole of a battery. The negative pole will be connected to the source of the transistors. The gate must be open. If we now touch with one hand the positive pole of the battery and with the other the gates, the lamp will light up. Now we touch the negative pole of the battery and simuntanously the gates and the lamp will be switched off. If this test is positive, the transistors are o.k.
Control unit: For testing the control unit, clamp "G" and clamp "C" must be connected to ground (minus pole). This prevents the load detection circuit from switch-off. The outputs "A" and "B" will show an output voltage between 3.5 and 4 volts. Theoretically the exact value should be 2.5 volts, according to a duty cycle of 25%, but the transformer is not yet connected and so the pulse width regulator will generate maximum value. If a frequency counter and an oscilloscope are available, the control signals may be checked and adjusted to 50 cycles or 20 milliseconds (period of the 50 cycle oscillation) at these outputs. During normal operation the transformer generates peak voltages up to 28 volts on clamp "D". The pulse width regulator may be tested, if variable DC voltages from 12 V to 28 V will be applied to this connection. For testing the current limiter, variable DC voltage may be applied to clamp "C" (0 ... 1 Volt). The switch-off should take place at about 0.35 volts.
The control unit may also be tested in connection with the mosfet transistors. Instead of the transformer, autolamps would be connected. The brightness of the lamps may now be adjusted by turning resistor R16 or connecting a DC voltage to clamp "D" as described above.
The autolamp also makes possible a very simple test to adjust the frequency. Therefore we put in series with the lamp the 12 volts output of a small tranformer, connected primarily to the mains supply. Both alternating voltages will now be added or subtracted, dependent on the phase shift. The lamp will flicker. The goal is, to make this flickering very slowly. Attention: The autolamp must be 24 volts or two lamps in series.

Sabtu, 11 Februari 2012


microcontroller chips appear on the market, today’s microcontroller programming tools are becoming more and more ‘universal’ to cope with different programming conventions. It is also sadly the case that the more ‘universal’ the programmer, the more you need to pay. In practice, most people will only use a fraction of the capabilities of such a programmer, making it difficult to justify such an expense. The project here describes a minimal solution to the programming problem for one of the most popular types of controller. The PIC16F84 (1k-Flash-memory) and the PIC16C84 (1k-ROM) with 13 I/O-lines.

Using a PC together with this relatively simple interface and some software it is possible to build a low cost programmer The design for the programmer is described on the author’s website. The programmer connects to the serial port of a PC. Pin 3 of the port supplies the power and zener diode D6 along with D5 regulates the supply to the chip at 5 V. C1 and C2 smooth the regulated supply. The unregulated supply is fed to pin MCLR of the PIC to configure it in programming mode. R1 limits current into this pin and an internal regulator ensures the correct programming voltage on chip. A high on this pin switches the PIC into programming mode.
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signal amplitude

The output signal amplitude is dependent on the area of the pulses, so for accurate signal reconstruction, both time alignment and rail voltage are critical parameters. Complex audio signals will also cause intermodulation via the power supplies unless a very low impedance supply is used.

The PWM signal is generated digitally and therefore the pulse widths are quantized. Practical considerations in the power output stage limit the maximum switching frequency (fsw), although higher frequencies allow easier filtering of switching noise in the reconstruction filter. The resolution in the PWM waveform is dependent on the ratio of the Master Clock (MCK) frequency to the switching frequency, which is usually a power of 2.

The digital PCM input is also quantized: a resolution of 32 bits gives a theoretical 194dB dynamic range, if limited solely by quantization noise. More practically, 24 bits (the best resolution of today's audio ADCs) has a theoretical 144 dB dynamic range.

The PWM resolution is typically much more coarse, in order to keep switching frequency above maximum audio sample rates of 192 kHz, whilst limiting MCK frequency. Typical ratios are between 32 (5 bits) and 256 (8 bits), giving a best dynamic range of 50 dB. Clearly, this means that other techniques are required to provide sufficient dynamic range, and the answer is oversampling with noise shaping. This technique essentially allows a time averaging of the PWM pulse widths to be applied, to deliver fractional resolution in the amplitude of the output signal.

The MCK of a digital amplifier, which needs a low jitter specification for good amplifier performance, will either need to be a fixed multiple of the incoming sample rate or else can be a fixed crystal generated frequency. The first case requires a phase locked loop, which is often a source of jitter. In the second case, a sample rate converter is required to re-align the incoming oversampled data with the MCK period.

Both oversampling and sample rate conversion use interpolation and averaging filters, requiring a large number of multiply accumulates, and hence MCK cycles, which add up to a signal group delay that is significant at audio frequencies. The delay is fixed and so affects the phase of all input signal frequencies linearly, which is benign in audio terms, but must be borne in mind for any feedback system comparing output with input.
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data processor

A programmable logic controller (PLC) is a special data processor used as controller for machines in industrial processes. As a part of process control, a programmable logic controller is used to monitor input signals from a variety of input points which report events and conditions occurring in a controlled process. During the execution of a stored control program, they read inputs from the controlled process and, per the logic of the control program, provide outputs to the controlled process. A PLC typically consists of an input section, a logic (or processing) section, an output section, and a power supply. A PLC is typically programmed with a sequential program for controlling a machine, such as a pressing or marking machine that continuously repeats the same motions during, for example, an automated assembly process or other manufacturing process. Programmable logic controllers can be programmed using different development platforms. One common development platform is called ladder logic. Ladder logic is a programming language based on executing commands on a line-by-line permission system. Each ladder logic program comprises one or more ladder logic statements. These ladder logic statements are often termed "rungs." Each ladder logic statement defines the relationship between an output variable and one or more input variables. Programmable logic controllers are used throughout industry to control and monitor a wide range of machines and other movable components and systems. A PLC can monitor such input conditions as motor speed, temperature, pressure, volumetric flow and the like.
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The SPN1001-FV1 is a complete reverb solution in a single IC.
With integrated stereo ADC and DACs, the FV-1 can be treated like any other analog component in your products signal path.
The FV-1 can access a total of 16 programs, 8 are built in to the internal ROM and the designer may elect to connect a serial EEPROM with 8 additional programs. By using an external EEPROM, the designer can create a custom program set without the need for a microprocessor in the system.
With 3 potentiometer inputs, programs may have real time variable parameters such as decay time in a reverb, rate and depth in a chorus or frequency in a filter. These inputs are available as coefficients to your program and may be used independently of each other.
The rich instruction set allows users to program effects of all kinds. With instructions like LOG and EXP, users can easily program audio expansion and compression routines. Integrated digital LFOs and ramp generators allow for programming chorus, flange and pitch shift.

Jumat, 10 Februari 2012

TV repair

Let TV repair done carefully and thoroughly as it can be fatal. Television is an electronic plane that has a high electrical voltage. In addition, of all the damage is not necessarily caused by the faulty component. Sometimes damaged due to poor solder tin so that the legs of components are not perfectly connected to the PCB. Symptoms and causes damage to various TV. The symptoms can be totally dead, no sound or picture produced ugly. Meanwhile, the damage can be caused by a TV that has component with age or relationship between the components is less than perfect

There is some damage that could lead to a TV set can not work at all. In general, this kind of damage occurs on the power supply (Power Supply) or the horizontal deflection circuit
What is the total dead TV and indicator lights go out?
Cause: most likely damage the power supply circuit
Solution: check the grid, a series regulator input to output
Consider the following regulator circuit schematic drawings. In general, TV has a power supply output voltage of 115 V, 24 V and 5 V, depending on the brand of TV. Replace damaged components and improve the circuit path is less than perfect. The arrows indicate the components that are easily damaged.

Is audible squeal vibration transformer switching?
Cause: The output voltage is usually blocked because of a faulty component. Solution: Remove the burden of the regulator by disconnecting the output transistor base horizontal or one foot horizontal transformer and measure the output voltage. If the output shows the voltage regulator in accordance with the instructions on the PCB, check that all the distribution channels of the output voltage regulator and a whole set of horizontal.

Consider the following horizontal circuit schematic drawings. In general, the usual components are easily damaged flyback transformer, horizontal transistor and a capacitor (see arrows).

Raster is not brightly lit screen even though the position of the maximum flyback.

Cause: The CRT anode voltage is too low due to the damage to the high voltage circuit, horizontal deflection circuit or power supply circuit. CRT cathode voltage all became great because of interference with the video amplifier. Solution: Have voltage regulator output is normal? If normal, check CRT cathode voltage. If not normal, check the regulator output voltage. Is the CRT cathode voltage normal? If normal, check the CRT anode voltage. If not normal, check the high voltage circuits.

Raster A Horizontal Line

Sources of interference depends on the oscillator used TV.

Solution: Check the vertical deflection circuit IC Check all electrode or a transistor with multitester.

Horizontal synchronization Bad
Black strips can not be lost even if the synchronization of the raster set.

Such damage is rare for a new TV output. If the damage happens, usually caused by a component that has been ingested age.
Check the horizontal oscillator circuit. The possibility exists that Elko is dry. Elko is usually indicated by the back that looks dull or broken.

Vertical synchronization Bad
Damage lies in the integrator or the vertical oscillator circuit. Such damage is usually common in an older TV. Solution:
Check the vertical oscillator circuit. TV vertical output regulator may long have worn, while the new TV damage caused by leaking ceramic capacitors.

The screen image narrows
Damage like this rarely happen on TV the new output. Lower voltage so that the horizontal output circuit current in the sawtooth horizontal deflection coil (yoke) to grow weak. Solution: Check the power supply output voltage. If a lower output voltage, check the components. Check the horizontal deflection circuit transistor is mainly present in it. Check the condition of the yoke, if it is damaged or frayed should be replaced

Horizontal Deflection Transistor
Widening the Horizontal
Such damage is caused by a defective Vr. Solution: Check the components. If the normal power supply voltage, check the CRT anode voltage If the CRT anode voltage is too low, check the circuit Change the value of VR, if no change in the VR switch. Check the power supply output voltage. If the output voltage is larger high-voltage amplifier.

The Top Or Bottom depreciation

Due to the value of Vr is not appropriate or electrolytic capacitors are dry.
Solution: Set VR, if no change in mean VR is broken. Check Elko are still good or it is dry
Image Vertical Aft
Sawtooth currents on the vertical deflection coil is too low. solution:
Adjust VR, if nothing changes it may Elko is dry.

Snow Noise Figure
Cause: The field intensity at low frequencies where the signal reception. Broken TV antenna system of high-frequency amplifier circuit is damaged Solution: Rotate the antenna to get good pictures. Fix path Check the antenna cable and solder the tuner AGC block.

Low Contrast Images

The damage is located between the mixer to the amplifier circuit video.
Check that there is a resistor whose value is enlarged or short.

Black Horizontal lines
Usually caused by a device that uses a small motor. solution:
Keep away from sources of noise of the TV.

Disturbed by Channel Picture Other
Cross-modulation occurs by a channel that has a large emittance. Solution: Adjust the TV antenna height Set the value of Vr AGC circuit
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