Friday, January 10, 2014
Simple Peak Indicator
A simple circuit, peak indicator of tops of musical signal. Each time where the level of signal exceeds the level + 4dB, turns on led D1. It is useful in each channel of console of sound, in final amplifiers or in that other application, to we needed. With the prices of circuit, the indicate begins with levels above + 4 dB (1.25V rms). For adaptation in different levels of signal, we can use a trimmer, before capacitor C1.
Peak Indicator Circuit Diagram :
R1 = 10K
R2 = 1.2K
R3 = 220K
R4 = 4.7K
R5 = 4.7K
C1 = 47uF-25V
C2 = 2.2uF-25V
Q1 = BC550C
Q2 = BC550C
D1 = Red LED
Notes:
- It can be assembled on a general purpose PCB.
- It can be powered from a 12V-15V regulated power supply.
Source : www.ecircuitslab.com/2011/05/simple-peak-indicator.html
Thursday, January 9, 2014
It is the place where cell phone jammers is necessary to be used
It is the place where cell phone jammers is necessary to be used
SMS one is not more than 70 words, sent from the platform to the user to receive the fastest just ten seconds; MMS a maximum capacity of about 40K or so, they can be quantified 10 (version), a total of 3000 words plus four pictures. During the Olympics, a huge crowd working life limit, in the absence or the move, this time, the convenience of the mobile newspaper will get the highlights. The mobile newspaper reported almost the only way they always watch the game. Even those people in front of the TV or computer all day, accustomed to the phone reported as the main source of information. After all, they care so deeply about the time of the live matches through mobile newspaper. It will supply the power for cell phone jammers itself.
You can use the minimum cost of reading to grasp all the games dynamic. Some even reported as a daily spectator guide. As of 24 on August 12, more than 10 million through China Mobiles "Olympics phone" concerned about the Olympic Games process. According to the survey interview, informed students on the use of mobile phones reported during the Olympic Games through the Olympic Mobile News Olympic Alerts feel convenient fashion. Some students said that each month as long as put into the cost of a few newspapers will be able to browse the entire month of Olympic information reports, cost-effective and innovative. Advantages: "Olympics phone" to take the combination of MMS and SMS text messages to ensure the timeliness, MMS meet the depth reading. It means the open wire and concealed wire laid on the wall where the installation of cell phone jammers will be carried out.
Early as the MMS one a day, one day a text message. July 1, 2008, increased to one day two MMS, SMS day three. Distinct content characteristics and strong technical support, Olympic mobile newspaper rapid expansion. To the Beijing Olympic Games start the first week, ordered the Olympic mobile newspaper users exceeded 10 million. The phone reportedly has a high arrival rate and circulation rate. This Olympic Games, millions of users are informed of Liu Xiang out of the race through the Olympic mobile phone SMS messages. Mobile terminal message, can be understood in a way to remind mandatory reading. Users also need to periodically delete old short color information in the phone to save memory space. It is the strong electricity around antenna of cell phone jammers .This removal process itself can also increase the likelihood of the second reading.
Here continue read..
SMS one is not more than 70 words, sent from the platform to the user to receive the fastest just ten seconds; MMS a maximum capacity of about 40K or so, they can be quantified 10 (version), a total of 3000 words plus four pictures. During the Olympics, a huge crowd working life limit, in the absence or the move, this time, the convenience of the mobile newspaper will get the highlights. The mobile newspaper reported almost the only way they always watch the game. Even those people in front of the TV or computer all day, accustomed to the phone reported as the main source of information. After all, they care so deeply about the time of the live matches through mobile newspaper. It will supply the power for cell phone jammers itself.
You can use the minimum cost of reading to grasp all the games dynamic. Some even reported as a daily spectator guide. As of 24 on August 12, more than 10 million through China Mobiles "Olympics phone" concerned about the Olympic Games process. According to the survey interview, informed students on the use of mobile phones reported during the Olympic Games through the Olympic Mobile News Olympic Alerts feel convenient fashion. Some students said that each month as long as put into the cost of a few newspapers will be able to browse the entire month of Olympic information reports, cost-effective and innovative. Advantages: "Olympics phone" to take the combination of MMS and SMS text messages to ensure the timeliness, MMS meet the depth reading. It means the open wire and concealed wire laid on the wall where the installation of cell phone jammers will be carried out.
Early as the MMS one a day, one day a text message. July 1, 2008, increased to one day two MMS, SMS day three. Distinct content characteristics and strong technical support, Olympic mobile newspaper rapid expansion. To the Beijing Olympic Games start the first week, ordered the Olympic mobile newspaper users exceeded 10 million. The phone reportedly has a high arrival rate and circulation rate. This Olympic Games, millions of users are informed of Liu Xiang out of the race through the Olympic mobile phone SMS messages. Mobile terminal message, can be understood in a way to remind mandatory reading. Users also need to periodically delete old short color information in the phone to save memory space. It is the strong electricity around antenna of cell phone jammers .This removal process itself can also increase the likelihood of the second reading.
Variable High Pass 20HZ to 200HZ Filter
A simple circuit, High-Pass filter, variable between frequencies 20HZ until 200HZ, useful in a lot of cases elaboration of sound signals. The regulation is achieved with the double potentiometer 47KΩ and the frequency response in his two extreme places, appears in the schematic.
Here continue read..
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| Variable High-Pass 20HZ to 200HZ Filter Circuit Diagram |
Friday, December 27, 2013
TDA2030A 35W Amplifier used in Home Theaters
TDA2030A is a well used class AB audio amplifier IC. This one is mostly used in nowadays home theater systems for it’s some good features,
This can be operated with single supply line, but that topology gives less output power, hence this bi-voltage topology is used everywhere. We need to provide +/- 12V to it. We can easily get +12V and -12V from a 12-0-12 CT step down transformer. And, as this IC doesn’t require regulated supply, we can feed voltage directly from rectifier with just a capacitor. Well, the IC costs around 25 rupees, and together with all other materials as PCB, other parts the cost of final board doesn’t exceed 70-75 rupees.
Here continue read..
- Small size IC(package PENTAWATT V, almost size of regular TO220)
- Maximum voltage range (upto 44Volts Vs MAx)
- Very low harmonic and cross-over distortion.
- Suited for more reliable applications without regulated supply
- Up to 35Watts RMS driver output
- Thermal shutdown protection
This can be operated with single supply line, but that topology gives less output power, hence this bi-voltage topology is used everywhere. We need to provide +/- 12V to it. We can easily get +12V and -12V from a 12-0-12 CT step down transformer. And, as this IC doesn’t require regulated supply, we can feed voltage directly from rectifier with just a capacitor. Well, the IC costs around 25 rupees, and together with all other materials as PCB, other parts the cost of final board doesn’t exceed 70-75 rupees.
Circuit Guards Amplifier Outputs Against Overvoltage
A universal requirement for automotive electronics is that any device with direct connections to the wiring harness must be able to withstand shorts to the battery voltage. Though brutal, this requirement is necessary for reliability and for safety. One example of the need for this protection is an audio amplifier that produces indicator noises in the automotive interior. Though operating from a voltage of 3.3 or 5V, which is lower than the battery voltage, the amplifier must be able to stand off the full battery voltage.
Circuit diagram :
During normal operation, the amplifier outputs’ dc components are at one-half of the VCC supply—2.5V in this case, for which VCC is 5V. The 11V gate drive fully enhances the MOSFETs, and the shunt-regulator output is off because its feedback input, Pin 5, is below its internal 0.6V threshold. If either output exceeds 5V, current flows through D3 into the R5/R6 divider, pulling the feedback terminal above its threshold. The shunt-regulator output then pulls the MOSFET-gate voltage from 11V almost to ground, which blocks high voltage from the amplifier by turning off the MOSFETs. The MOSFETs easily withstand the continuous output voltage, and the circuit returns to normal operation when you remove the short. Because the circuit does not respond instantaneously, zener diodes D1 and D2 provide protection at the beginning of a fault condition.
Figure 2. In Figure 1, one of U1s two audio outputs (top trace) is protected when its external terminal accidentally contacts an 18V supply voltage (2nd trace).
The waveforms of Figure 2 represent an operating circuit. One of the amplifier’s outputs (Trace 1) is a 1-kHz sine wave biased at a dc voltage of 2.5V. Trace 2 is the signal on the wire harness. It also starts as a 1-kHz sine wave biased at a 2.5V-dc voltage, but, at 200 µsec, it shorts to an 18V supply. Trace 3 is the shunt regulator’s output, initially biased at 11V but pulled to ground in response to the overvoltage condition. Trace 4 is current in the wire harness. Initially a sine wave, this current drops to zero in response to the overvoltage condition.
The components in Figure 1 optimize this circuit for 5V operation. For other voltages, you can adjust the R5/R6 resistor values. The shunt regulator must be able to function in saturation and, therefore, requires a separate supply pin in addition to the shunt output pin. The circuit repeatedly withstands 28V shorts without damage.
Circuit diagram :
Figure 1 : This output circuit provides continuose protection against overvoltge faults
You can also use a protection network appropriate for these amplifiers for other automotive circuits (Figure 1). A dual N-channel MOSFET disconnects the amplifier’s outputs from the wiring harness in response to a high-voltage condition on either output. The MOSFETs, Q1A and Q1B, are normally on; zener diode D4 and its bias components drive the MOSFETs’ gates to approximately 11V. Dual diode D3 provides a diode-OR connection to the dc voltage on each output, thereby producing a voltage that controls the output of shunt regulator IC2. The circuitry protects IC1, a 1.4W Class AB amplifier suitable for audible warnings and indications for the automotive electronics. During normal operation, the amplifier outputs’ dc components are at one-half of the VCC supply—2.5V in this case, for which VCC is 5V. The 11V gate drive fully enhances the MOSFETs, and the shunt-regulator output is off because its feedback input, Pin 5, is below its internal 0.6V threshold. If either output exceeds 5V, current flows through D3 into the R5/R6 divider, pulling the feedback terminal above its threshold. The shunt-regulator output then pulls the MOSFET-gate voltage from 11V almost to ground, which blocks high voltage from the amplifier by turning off the MOSFETs. The MOSFETs easily withstand the continuous output voltage, and the circuit returns to normal operation when you remove the short. Because the circuit does not respond instantaneously, zener diodes D1 and D2 provide protection at the beginning of a fault condition.
Figure 2. In Figure 1, one of U1s two audio outputs (top trace) is protected when its external terminal accidentally contacts an 18V supply voltage (2nd trace).The waveforms of Figure 2 represent an operating circuit. One of the amplifier’s outputs (Trace 1) is a 1-kHz sine wave biased at a dc voltage of 2.5V. Trace 2 is the signal on the wire harness. It also starts as a 1-kHz sine wave biased at a 2.5V-dc voltage, but, at 200 µsec, it shorts to an 18V supply. Trace 3 is the shunt regulator’s output, initially biased at 11V but pulled to ground in response to the overvoltage condition. Trace 4 is current in the wire harness. Initially a sine wave, this current drops to zero in response to the overvoltage condition.
The components in Figure 1 optimize this circuit for 5V operation. For other voltages, you can adjust the R5/R6 resistor values. The shunt regulator must be able to function in saturation and, therefore, requires a separate supply pin in addition to the shunt output pin. The circuit repeatedly withstands 28V shorts without damage.
Source : http://www.ecircuitslab.com/2012/06/circuit-guards-amplifier-outputs.html
10 Band Equalizer
The equalizer presented in this article is suitable for use with hi-fi installations, public-address systems. mixers and electronic musical instruments. The relay contacts at the inputs and outputs, in conjunction with S2, enable the desired channel to be selected. The input may be linked directly to the output, if wanted. The input impedance and amplification of the equalizer are set with S1 and S3. The audio frequency spectrum of 31 Hz to 16 kHz is divided into ten bands. Ten bands require ten filters, of which nine are passive and one active. The passive filters are identical in design and differ only in the value of the relevant inductors and capacitors. The requisite characteristics of the filters are achieved by series and parallel networks.
The filter for the lowest frequency band is an active one to avoid a very large value of inductance. It is based in a traditional manner on op amp A1. The inductors used in the passive filters are readily available small chokes. The filter based on L1 and L2 operates at about the lowest frequency (62 Hz) that can be achieved with standard, passive components. The Q(uality) factor of the filters can, in principle, be raised slightly by increasing the value of R19 and R23, as well as that of P1–P10, but that would be at the expense of the noise level of op amp IC1. With component values as specified, the control range is about ±11 dB, which in most case will be fine. A much larger range is not attainable without major redesign.
10-Band Equalizer Circuit diagram:
The input level can be adjusted with P1, which may be necessary for adjusting the balance between the channels or when a loudness control is used in the output amplifiers. Several types of op amp can be used:in the prototype, IC1 is an LT1007, and IC2, an OP275. Other suitable types for IC1 are OP27 or NE5534; and for IC2, AD712, LM833 and NE5532. If an NE5534 is used for IC1, C2 is needed; in all other cases, not. The circuit needs to be powered by a regulated, symmetrical 15 V supply. It draws a current of not more than about 10mA.
Source : http://www.ecircuitslab.com/2011/05/10-band-equalizer.html
Battery powered Headphone Amplifier
Low distortion Class-B circuitry 6V Battery Supply
Battery-powered Headphone Amplifier Circuit diagram
- For a Stereo version of this circuit, all parts must be doubled except P1, SW1, J2 and B1.
- Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to maximum resistance and Trimmer R3 to about the middle of its travel.
- Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.
- Switch on the supply and measure the battery voltage with a Multimeter set to about 10Vdc fsd.
- Connect the Multimeter across the positive end of C4 and the negative ground.
- Rotate R3 in order to read on the Multimeter display exactly half of the battery voltage previously measured.
- Switch off the supply, disconnect the Multimeter and reconnect it, set to measure about 10mA fsd, in series to the positive supply of the amplifier.
- Switch on the supply and rotate R6 slowly until a reading of about 3mA is displayed.
- Check again the voltage at the positive end of C4 and readjust R3 if necessary.
- Wait about 15 minutes, watch if the current is varying and readjust if necessary.
- Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.
Output power (1KHz sinewave):
16 Ohm: 100mW RMS
32 Ohm: 60mW RMS
64 Ohm: 35mW RMS
100 Ohm: 22.5mW RMS
300 Ohm: 8.5mW RMS
Sensitivity:
160mV input for 1V RMS output into 32 Ohm load (31mW)
200mV input for 1.27V RMS output into 32 Ohm load (50mW)
Frequency response @ 1V RMS:
flat from 45Hz to 20KHz, -1dB @ 35Hz, -2dB @ 24Hz
Total harmonic distortion into 16 Ohm load @ 1KHz:
1V RMS (62mW) 0.015% 1.27V RMS (onset of clipping, 100mW) 0.04%
Total harmonic distortion into 16 Ohm load @ 10KHz:
1V RMS (62mW) 0.05% 1.27V RMS (onset of clipping, 100mW) 0.1%
Unconditionally stable on capacitive loads
Source : http://www.ecircuitslab.com/2012/04/battery-powered-headphone-amplifier.html
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