Identify diagram: a

Showing posts with label a. Show all posts

Tuesday, 9 April 2013

A Low Distortion Audio Pre amplifier

In an audio amplifier the quality of sound depends upon a number of factors, e.g. quality of active and passive components, circuit configuration, and layout. To an extent, the selection of components depends on the constructor’s budget. The discrete active components like transistors have been increasingly replaced by linear ICs, making the task of designer easier. With the passage of time, the general-purpose op-amps like LM741, which were being used in audio/hi-fi circuits, have become The preamplifier circuit presented here is based on a dual precision op-amp for the construction of a low distortion, high quality audio preamplifier.

Low Distortion Audio Pre-amplifier Circuit diagram:

A dual op-amp OPA2604 from Burr-Brown is used for all the stages. The FET input stage op-amp was chosen in this context it is worthwile to mention another popular bi-polar architecture op-amp, the NE5534A. It has, no doubt, an exceptionally low noise figure of 4nV/ÖHz but rest of the specifications compared to OPA2604 are virtually absent in this IC. Also This IC is also capable of operating at higher voltage rails of ± 24V (max.). Also its input bias current (100 pA) is many orders lower than its bipolar counterpart’s. This ensures a multifold reduction in noise.

A channel seperation of 142 dB exists between In the circuit, buffer is essential for the proper working of the subsequent blocks. A nominal input impedance of 47k is offered by this stage which prevents overloading of the preamplifier. The tone control is a baxandall type filter circuit.The bandwidth limiter is basically a low-pass filter with an upper cut-off ceiling at the end of the useful audio spectrum. The gain at 10 kHz is approximately 17 dB. The design is essentially 3-pole type and the upper frequency is set at 25 kHz. This lSetting the unit is fairly simple. Check the power leads feeding the IC for symmetrical voltages. High quality audio output from the line output socket is to be fed as the input signal to this preamplifier. Output of the preamplifier is fed to the power a The whole circuit consumes about 10 mA when the above-mentioned ICs are used. Power supply requirements are not critical as the circuit works on 7.5V to 15V DC..

Source : http://www.ecircuitslab.com/2012/01/low-distortion-audio-pre-amplifier.html

Wednesday, 3 April 2013

A Low Cost Hearing Aid Circuit

Small and portable unit, Useful for old men and old women

This low-cost, general-purpose electronic hearing aid works off 3V DC (2x1.5V battery). The circuit can be easily assembled on a veroboard. For easy assembling and maintenance, use an 8-pin DIP IC socket for TDA2822M.

Circuit Diagrams:

A Low Cost hearing Aid Circuit

Parts:

P1 = 10K
R1 = 2.2K
R2 = 330K
R3 = 680R
R4 = 33R
R5 = 100R
R6 = 4.7R
R7 = 4.7R
R8 = 220R
C1 = 0.01uF-10V
C2 = 100nF-63V
C3 = 47uF-10V
C4 = 10uF-10V
C5 = 0.01uF-10V
C6 = 100uF-10V
C7 = 100nF-63V
C8 = 100nF-63V
D1 = Red LED
Q1 = BC547
IC1 = TDA2822M
EP1 = Mono Earphone 32R
SW1 = On-Off Switch

Circuit Operation:

In this circuit, transistor Q1 and associated components form the audio signal preamplifier for the acoustic signals picked up by the condenser microphone and converted into corresponding electrical signals. Resistor R5 and capacitor C3 decouple the power supply of the preamplifier stage. Resistor R1 biases the internal circuit of the low-voltage condenser microphone for proper working. The audio output from the preamplifier stage is fed to the input of the medium-power amplifier circuit via capacitor C2 and volume control P1.

The medium-power amplifier section is wired around popular audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for portable low-power applications, is readily available in 8-pin mini DIP package. Here the IC is wired in bridge configuration to drive the 32-ohm general-purpose monophonic earphone. Red LED (D1) indicates the power status. Resistor R8 limits the operating current of D1. The audio output of this circuit is 10 to 15mW and the quiescent current drain is below 1 mA.

Source : www.electronsforu.com

Tuesday, 2 April 2013

How to Installation A Car Stereo

Car Stereo Installation Guide - Want to save some money? Ever wonder if you could do a car stereo installation yourself? Yes, you can do it yourself! Go ahead, spend that money on your hardware! Don’t spend it on labor. Besides, doing a car stereo installation yourself can be a very rewarding experience, not to mention you can learn a lot from it too. Nothing beats the feeling of seeing your “creation” in action, running smoothly and perfectly.

But be very careful, you really won’t want to damage your expensive hardware. Well, most car audio hardware are no-brainers to install, you’d find that most of the time the parts have specially shaped sockets and slots etc. and would only fit where it’s supposed to be installed. Still, it’s best to proceed methodically.

In a car stereo installation, you have to determine what kind of rig you’re going to put into your vehicle. If you’re a beginner, it’s best you do a car stereo installation if it’s just a simple system. You may want to leave the complicated stuff to the professionals, like installing delicate equipment like LCD panels, motorized parts etc. especially if it requires the creation of custom panels and such.

Head units are one of the easiest to do in a car stereo installation. Fortunately, most units follow the same size standards (DIN). In many cars, once the factory radio is removed the aftermarket radio will fit in the hole. In many other cars, a kit is needed if the factory hole is too big, or not deep enough. In some cases the dash has to be cut. Any car stereo store should have kits required for installation.

There are two types of mounting in a car stereo installation. ISO mounting is when the radio can be screwed to existing factory radio brackets, such as in most Japanese cars. Ring mounting is when an aftermarket radio comes with a metal ring that gets mounted to the factory radio hole or aftermarket kit via bendable tabs. In many cars, dash and trim rings have to be filed to enlarge the radio hole. Once the ring is installed, the radio slides in and is held by snaps. In most cases, special tools are required to remove the radio.

Speakers are very critical in a car stereo installation. No matter how expensive your speakers are, if they are not properly installed, the sound will not be up to par.

In a simple car stereo installation, you’ll probably be using speakers that fit into a factory location. Just make sure there are no gaps or holes. Sometimes building a wood or fiberglass baffle helps reduce holes and gives you much better sound. But always be careful when using power tools around speakers. Car stereo installation warranties usually dont cover holes in speakers.

For unconventional speaker locations, sometimes metal has to be cut. You might want to leave this to the professionals, tools like plasma cutters and pneumatics drills are required. But if you’re going to insist, a pair of metal snips (left and right cut) will do.

A car stereo installation has to put up with vibrations and other noise sources in its environment. Even though it is impossible to eliminate these completely, there are products that will greatly decrease the noise and rattling, particularly on non-luxury cars. Liners, sprays and adhesive strips and even carpeting applied onto the panels can make a world of difference.

Saturday, 30 March 2013

Make a Single Chip Programmable Voice Audio Recorder Circuit

The article explains a single chip circuit which can be used for recording short voice clips or any audio clip ranging from 20 to 60 seconds. The incorporated IC APR9600 is a programmable voice recorder chip which facilitates infinite number of recording/erase of audio files in it as per user preference.

The recording or storage of the audio can be done through an integrated electret mic or via any line out or RCA port of an audio reproducing device.

However since the IC is a low bit device does not support Hi-Fi recording rather low quality music.

The sampling rate or the frequency response is limited to just 8 kHz max thats pretty ordinary if we compare it with the specs of modern Hi-Fi equipment.

Nevertheless, the IC is a stand alone device which does not depend on any external circuits, just plug it in, and it starts recording whatever voice data is fed across its input pins. Moreover since the data can be erased and refreshed any number of times, the unit becomes completely programmable and a pretty useful gadget.

Image courtesy: http://www.datasheetcatalog.org/datasheet/aplus/APR9600.pdf

Circuit Description

The proposed circuit of a programmable single chip voice recorder/player utilizes the IC APR9600 as the main processor of the circuit.

Its a 28 pin IC which can be very easily and quickly configured for getting the required results by adding a handful of common passive electronic components.

All the pin outs of the IC are specified by their individual functions, and the components are accordingly attached with the respective pinouts.

For example pin#28 and pin#27 are assigned as the trigger inputs for initiating playback and recording functions.

Sliding the connected switch toward right initiates the playback action while toggling it toward left puts the IC in the recording mode.

The IC also has appropriate visual indication options which provide the user with instant information regarding the position of the circuit.

The LED at pin#8 indicates the end of a playback file session.

The LED at pin#10 stays illuminated for so long the audio is being played, indicating circuit "busy"

The LED at pin#22 indicates through rapid flashes regarding the playback or recording modes of the IC.

The input data is normally picked from the mic which is appropriately connected across the pins 17 and 18 of the IC.

When the slider switch is pushed toward the recording mode, any audio entering the mic gets stored inside the IC until the specified time elapses.

The sampling rate of the IC can be set as per the user preference. Lower sampling rates will provide longer recording/playback periods and vice versa.

Longer periods would also mean lower voice quality while shorter periods of recording spec will produce relatively better sound processing and storing.

The entire circuit operates with a 5 volt supply which can be acquire through a standard 7805 IC after rectification from a standard transformer bridge capacitor network.

The audio output may be derived across pin#14 and ground which must be terminated to an audio amplifier so that the data can be heard with proper volume.

Thursday, 28 March 2013

10 to 14W Class A Audio Amplifier

I have built this amplifier and it does sound good. It requires a preamp as it hasnt got much gain. It requires big heat sinks and a large transformer and a great power supply and careful wiring, but in the end it is xtremely simple and it sounds very good. The zener diode rejects any ripple coming from the power supply, But you still only want a ripple of 10mV max. The ripple reaching the input is amplified, so the zener diode gets rid of that, but whatever ripple there is will still reach the power stage.

Wednesday, 27 March 2013

How to Make a LED Chaser cum Blinker Circuit Using IC 4017

The presented circuit was requested by Mr.Joe, one of the keen followers of this blog. The circuit initially was intended to be used for generating LED strobe light effects and was asked to be modified such that it could be used as an LED sequencer as well as a blinker. The change over would be implemented via a toggle switch.

The circuit diagram may be understood with the following points:

The IC 4017 is not new to us and we all know how versatile and competent this device is. Basically the IC a Johnson’s decade counter/divide by 10 IC, fundamentally used in applications where sequencing positive output signals are required or desired.

The sequencing or the orderly shifting of the outputs take place in response to a clock pulse that needs to be applied at the clock input pin #14 of the IC.

With every rising positive edge of the clock input, the IC responds and pushes its output’s positive from the existing pin out to the next pin out in the order.

Here a couple of NOT gates are used as a oscillator for providing the above clock pulses to the IC 4017. VR1 may be adjuted for determining or fixing the speed of the sequencing.

The outputs of the IC are connected to an array of LEDs in a specific order which makes the LEDs look like as if they are running or chasing during the operations.

If the circuit would be required only to produce the chasing effect, the diodes would not be required, however as per the present ask the diodes become important and allows the circuit to be used as a blinker also, depending upon the position of the switch S1.

When the switch S1 is positioned at A, the circuit behaves like a light chaser and produces the normal chasing effect over the LEDs which start illuminating in sequence from top to the bottom, repeating the operations as long as the circuit remains powered.

As soon as S1 is flicked toward B, the clock signals from the oscillator are shifted into the input of the transistor T1, which instantly stats to pulsate all the LEDs together in response to the received clocks from N1/N2 configuration.

Thus as per the requirement we have successfully modified an ordinary light chaser circuit with an additional feature through which the circuit now is also able to function as a LED flasher.

Do not forget to connect the inputs of the remaining unused gates from the IC 4049 either to the positive or the negative of the supply. The supply pins of the IC 4049 also need to be connected to the relevant supply rails of the circuit, kindly refer to the datasheet of the IC.

Tf all the ten outputs of the IC 4017 are required to be integrated with LED sequencing, just connect pin #15 of the IC to ground and use the left over outputs of the IC for the required sequencing of the LEDs in the order of: 3,2,4,7,10,1,5,6,9,11

Parts List

The fooliwng parts will be needed for making this LED light chaser cum flaher circuit:

R1, R2, R3 = 1K,

VR1 = 100K linear pot.

All LED resistors are = 470 Ohms,

All diodes are = 1N4148,

All LEDs = RED, 5mm or as per choice,

T1 = 2N2907, or 8550 or 187,

C1 = 10uF/25V

C2 = 0.1uF,

IC1 = 4017,

N1, N2 = IC4049