This document describes the design of a 16-channel audio mixer. It begins with an introduction to audio mixers and their uses. It then discusses the design methodology, considering factors like the number of input/output channels, power requirements, cost, and portability. The design is divided into several stages: a power stage using a step-down transformer and rectification circuit, a stereo stage for each channel with gain, bass, and treble controls, an auxiliary stage to boost the output signal, and a volume control stage to jointly control the levels. Block diagrams and circuit diagrams are provided to illustrate the design. In conclusion, the 16-channel audio mixer is tested by connecting it to an external amplifier and speakers.
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong,
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong,
A complete description of including circuit diagram, gain equation, features of Instrumentational amplifier , its working principle, applications, practical circuits, Proteus simulation and conclusion.
Uet, Peshawar Pakistan
Batch-06
hiii,, I am Anamika Singh, B.Tech student(Bengal college of Engineering and technology, Durgapur) and I am a ECE student.Here this is my 1st power point presentation. Hope you like it. I just want to check to level of my ppt knowledge . If u like if then of course download that share that.
All about Op-amp. In this power point presentation we know that what is op-amp, what is its circuit symbol, various type of op-amp, its pin diagram, its block diagram, its important terms and equation, ideal characteristics, voltage transfer characteristics.. etc. its a complete package of ppt on op-amp
hope u like it.
(-_-)
You can learn about ECG AMPLIFIER, INSTRUMENTATION AMPLIFIER, ECG AMPLIFIER DIAGRAM, VALUE OF RC TIME CONSTANT ?, DRIVEN-RIGHT-LEG SYSTEM, EQUIVALENT CIRCUIT FOR THE INPUT OF AN ECG AMPLIFIER, Method to increase input impedance, Active filters, FREQUENCY RESPONSE, LOW PASS FILTER, HIGH PASS FILTER, BAND PASS FILTER, Resonant frequency, Quality factor or Q factor
VIDEO LINK: https://youtu.be/sBG17ffSh40
Refer this link to get idea about instrumentation amplifier
https://youtu.be/-j8ePvHOuGk
Smart Autonomous Mobile detector RobotPunit Tiwari
SMART AUTONOMOUS MOBILE DETECTOR ROBOT
-This device can notice the use of GSM mobile phone in mobile restricted areas such as Examination hall or confidential rooms etc.
-It is just like a sniffer mobile that can sense the activity of mobile phone from a distance of 5 meters or more.
Timer with audible warning with circuit Diagram Team Kuk
From detectors to automobiles, audible alarms (also known to be called buzzers) have become a part of our everyday life. Some of the uses of these alarms are innocuous such as in a microwave oven. However, in some applications such as in a smoke detector or medical equipment, a person’s life may depend upon the audible warning sound. In all cases, the equipment designer should consider the desired characteristics of the audible alarm at the initial design-planning phase to obtain satisfactory performance and avoid costly redesign. The first characteristic for a designer to consider is the type of sound such as a continuous, intermittent or specialty sound. Other critical criteria include sound level, frequency, current draw, quality, mounting configuration, cost, and availability
A complete description of including circuit diagram, gain equation, features of Instrumentational amplifier , its working principle, applications, practical circuits, Proteus simulation and conclusion.
Uet, Peshawar Pakistan
Batch-06
hiii,, I am Anamika Singh, B.Tech student(Bengal college of Engineering and technology, Durgapur) and I am a ECE student.Here this is my 1st power point presentation. Hope you like it. I just want to check to level of my ppt knowledge . If u like if then of course download that share that.
All about Op-amp. In this power point presentation we know that what is op-amp, what is its circuit symbol, various type of op-amp, its pin diagram, its block diagram, its important terms and equation, ideal characteristics, voltage transfer characteristics.. etc. its a complete package of ppt on op-amp
hope u like it.
(-_-)
You can learn about ECG AMPLIFIER, INSTRUMENTATION AMPLIFIER, ECG AMPLIFIER DIAGRAM, VALUE OF RC TIME CONSTANT ?, DRIVEN-RIGHT-LEG SYSTEM, EQUIVALENT CIRCUIT FOR THE INPUT OF AN ECG AMPLIFIER, Method to increase input impedance, Active filters, FREQUENCY RESPONSE, LOW PASS FILTER, HIGH PASS FILTER, BAND PASS FILTER, Resonant frequency, Quality factor or Q factor
VIDEO LINK: https://youtu.be/sBG17ffSh40
Refer this link to get idea about instrumentation amplifier
https://youtu.be/-j8ePvHOuGk
Smart Autonomous Mobile detector RobotPunit Tiwari
SMART AUTONOMOUS MOBILE DETECTOR ROBOT
-This device can notice the use of GSM mobile phone in mobile restricted areas such as Examination hall or confidential rooms etc.
-It is just like a sniffer mobile that can sense the activity of mobile phone from a distance of 5 meters or more.
Timer with audible warning with circuit Diagram Team Kuk
From detectors to automobiles, audible alarms (also known to be called buzzers) have become a part of our everyday life. Some of the uses of these alarms are innocuous such as in a microwave oven. However, in some applications such as in a smoke detector or medical equipment, a person’s life may depend upon the audible warning sound. In all cases, the equipment designer should consider the desired characteristics of the audible alarm at the initial design-planning phase to obtain satisfactory performance and avoid costly redesign. The first characteristic for a designer to consider is the type of sound such as a continuous, intermittent or specialty sound. Other critical criteria include sound level, frequency, current draw, quality, mounting configuration, cost, and availability
A Plasma Tweeter is an audio device which uses a pair of electrodes as a source of sound. It has a clear reproduction and Omni directional radiation pattern. A plasma tweeter has a better frequency response than a conventional speaker and does not involve any moving part (diaphragm) and thus has less reverberation and no wear and tear. Plasma tweeters invented earlier were very expensive. This paper presents a plasma audio system which is making the regular audio system more efficient because of the use of the latest plasma tweeter. Here the objective is to create a low cost and more efficient version of the most speakers invented till now with the complete audio system.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
Development of a receiver circuit for medium frequency shift keying signals.inventionjournals
Frequency shift keying (fsk) mode of digital signal information transfer switches between two predetermined frequencies of the carrier wave, either by modulating one sine wave oscillator or by switching between two oscillators.The need for a receiver to decode an fsk signal along the transmitting medium from a digital source code within about 5 kilometer radius for security monitoring of environment informed this work. The design of a receiver circuit at a frequency of 500 kHzfor an input frequency shift keying (fsk) signal from a transmitter is presented. The receiver is to receive an RF signal, amplify it, filter it to remove unwanted signals, and recover the desired base band information. It consists of an amplifier, tuned circuitsand mixers which filters the base-band information. A comparator circuit is incorporated, to detect the digital signal received. The output from the comparators is the digital equivalent of the coded signals sent by the transmitter circuit, and transferred to a microcontroller circuit, to act as a coded signal representing information from the transmitting end. The bode-plot response of the receiver to the incoming signals using a FET tuned circuit, shows that only frequencies above 470kHz, and below 495kHz are allowed to pass through the network with a resonant frequency of 483.553 kHz and a gain of 27.734dB, while others are totally attenuated. The reliability of the designed receiver circuit was evaluated for a 1 year continuous operating period and was found to be 74.7%.Area of application of this work include electronic policing of a defined environment with good success
Design of up converter at 2.4GHz using Analog VLSI with 22nm Technologyijsrd.com
Up converter has been designed in 0.18μm technology at 2.4GHz Frequency. I am trying to design up converter with 22nm technology. The problems related to Up converter is often difficult to solve, and may allow different solutions, so the choice is not always simple for those engineers and professionals who are not trained in Analog VLSI. The optimal solution of Problem of Power dissipation is usually a mix of solutions for a specific situation. In such a situation, it is necessary to identify that problem and propose different solutions. Initially the thesis gives a basic idea of up converter and also about CMOS. Later on it tries to simulate the basic gates. And a detailed insight is provided with the help of a simulation using Tspice Simulator. Power Dissipation in 0.18μm Technology using current mirror gilbert mixer is 4.5 mW and in 0.25μm Technology using current mirror gilbert mixer is 3.5mW and Power Dissipation in 0.18μm Technology is 8.1mW using Gilbert mixer. Now I am trying to design mixer with low power dissipation with 22nm technology which is recent technology.
“Microcontroller Based Substation Monitoring system with gsm modem”.Priya Rachakonda
• The system is used for transmitting the message to predefined number about the
status of electrical parameters such as voltage, current, temperature etc., to improve
the quality of power.
• Studied about the protection, monitoring and control of a power system.
Implementation of Simple Wireless NetworkNiko Simon
End of course project where students were given free rein to explore wireless concepts through analysis of theory and hardware builds. The transmitter sends a Morse code audio signal which is then outputted by the receiver. Test of Morse code output: https://youtu.be/-06qOH7lYCg
Pre Final Year project/ mini project for Electronics and communication engine...Shirshendu Das
Mini project for Electronics and communication engineering (ECE) to build an AC to DC power supply using Full Wave Rectifier having input as 220-240V AC and giving stable filtered output of 5V, -5V & variable 5V DC. Simulation of the circuit was done in Proteus design suite.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
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Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
1. IOSR Journal of Electronics and Communication Engineering (IOSR-JECE)
e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 7, Issue 1 (Jul. - Aug. 2013), PP 59-64
www.iosrjournals.org
www.iosrjournals.org 59 | Page
Design of 16 Channel R.F. Mixer
1
Olawoye T. O. And 2
stephen-Lemo O. K.
1
Department of Computer Engineering Technology
2
Department of Electrical Electronics Engineering Technology Rufus Giwa Polytechnic, Owo, Ondo State.
Abstract: An audio mixer amplifier is a device that translates a signal of one frequency band to another. It will
accept many inputs at different frequencies and generate an output of the combination or sum of the
frequencies. The mixer circuit provides good gain to weak audio signals. It can be used in front of an R.F.
oscillator to make an R.F. receiver that is very sensitive to sound. Each input can be independently controlled
by a variable resistor. There is also a provision for a balance control to fade out signal while simultaneously
fading in the other.
Key Words: Audio Mixer, Frequency, Signal, Circuit.
I. Introduction
A.M. radio receivers can be broadly classified into two types viz., straight radio receiver and
superhetrodyne radio receiver. The former was used in the early days of radio communication. However at
present, all radio receivers are of superhetrodyne type.Straight radio receivers were used to reproduce radio
waves into sound waves. The aerial receives radio waves from different broadcasting stations the signal is
amplified decoded and theresulting audio signal is amplified and fed to the speaker for sound reproduction. The
major limitation of straight radio receivers are (i) tuned circuits are used. This is because it is necessary to
change the value ofvariable capacitors (gang capacitors) for tuning to the desired station, therefore, there is a
considerable variation of charge between the closed and open positions of the variable capacitors. This
changesthe sensitivity and selectivity of the radio receivers.(ii) There is too much interference of adjacent
stations.
The shortcomings of straight radio receiver wave is overcome by the invention of superheterodyne
receiver by Edwin H. Armstrong during the First World War. At present, all modern receivers utilise the
superhetrodyne circuit. In this type of radio receiver, theselected radio frequency is converted to a fixed lower
value, called intermediate frequency (IF). Thisis achieved by a special electronic circuit called mixer circuit.
There is a local oscillator in the radio receiver itself. This oscillator produces high frequency waves. The
selected radio frequency ismixed with the high frequency wave by the mixer circuit. In this process, beats are
produced and themixer produces a frequency equal to the difference between local oscillator and radio wave
frequency. The circuit is so designed that oscillator always produces a frequency 455kHz above the selected
radio frequency. Therefore, the mixer will always produce an intermediatefrequency of 455 kHz regardless of
the station to which the receiver is tuned. A frequency mixer is necessary to produce the intermediate frequency
in a superheterodyne receiver.
Mixer
A frequency mixer is a 3-port electronic circuit. Two of the ports are “input” ports and the other port is
an “output” port. The ideal mixer “mixes” the two inputsignals such that the output signal frequency is either the
sum (or difference) of the inputs frequencies. In other words:
fout = fin1 ± fin2 (1)
The nomenclature for the 3 mixer ports are the LocalOscillator (LO) port, the Radio Frequency (RF)
port, andthe Intermediate Frequency (IF) port. The LO port istypically driven with either a sinusoidal continuous
wave(CW) signal or a square wave signal. The choice to applya CW or square wave signal depends on the
applicationand the mixer. Conceptually, the LO signal acts as the“gate” of the mixer in the sense that the mixer
can beconsidered “ON” when the LO is a large voltage and“OFF” when the LO is a small voltage. The LO port
isusually used as an input port.(Marki&Marki, 2010).
The other 2 ports of the mixer, the RF and IF, can beinterchanged as either the second input or the
outputthe actual configuration depends on the application.When the desired output frequency is lower than
thesecond input frequency, then the process is calleddownconversion and the RF is the input and the IF isthe
output. The relationship between input and outputfrequencies is given by:
2. Design Of 16 Channel R.F. Mixer
www.iosrjournals.org 60 | Page
II. Design Methodology
In the design of audio mixer (16-channel), the following were taken into consideration:
(i) The audio mixer: This has to do with the mixer itself which is a device that combines a number of
audio signals at its input to produce an audio output. That is, it deals with audio signals only.
(ii) The needs of the Mixer: This involves:
(a) The input devices for sound such as microphone, tape recorders, guitars, etc.
(b) The output devices such as amplifiers and loudspeakers.
(c) The power supply to operate it and also the internal power requirements of the components
used.
(iii) Places of Application or Uses: These include conference halls, open fields or music industry.
(iv) Cost Implication: This involves the cost of materials and that of labour and construction which must be
as economical as possible
Considering the points raised above, one arrived at having an audio mixer that:
(i) Is efficient in combining a number of audio signals to produce a fine audio output with means of
filtering of noise that may accompany the input signal. So, filtering circuits are then incorporated with
the use of resistors and capacitors (discussed later);
(ii) Has input and output outlets for input and output devices - jackplug sockets were used to achieve this;
(iii) is able to use the common 220-240v a.c. mains as its power supply and also a small step-down
transformer (240/9v) to take care of the internal power requirements for the components;
(iv) is compact (not too big or heavy) and can be carried about easily as it is to be used with other heavy
equipment;
(v) Is economical and the components are readily available to come by in the market. Also, repairs (if
faulty) must be simple.
THE DESIGN
The major design which results from the factors enumerated above was achieved by dividing the
project into a number of stages. The stages are:
(a) Power stage
(b) Stereo stage
(c) Auxiliary stage
(d) Volume control stage
Power Stage
The stage involves the use of a 240/9V transformer, two 3300µF 35V capacitor and two IN5408 power
diodes. The description and use of the components were discussed' earlier under review of components (Chapter
Two). The diagram of the power stage is shown below.
Figure 3.1: Diagram of Power Stage
D - Diode (1N5408)
C – Electrolytic capacitor (330µFf 35V)
S - Switch
To choose the mains transformer the voltage requirement of the mixer circuits and the components
used were considered. The voltage requirements 3 - 12V. So the transformer must be one that will be able to
produce a voltage of 12V or a little above bearing in. mind that the rating on a transformer is normally in Root
Mean Square (RMS).
From the relation
Peak voltage Vp = 2 x R.M.S voltage, Vrms
rmsP VV 2
D
D
D
D +
-
3. Design Of 16 Channel R.F. Mixer
www.iosrjournals.org 61 | Page
2
P
rms
V
V
For VP = 12
Vrms = 8.485V
Considering the rating of the available transformers, the above value (S.4S5V) can be approximated to
9V. Therefore, a 240/9V transformer was chosen. With a 9V transformer the peak voltage,
92 PV
= 12.7V
The 0.7V difference is still very normal when one considers the low voltage from the mains supply
which may even be below 200V atimes.
For the diodes used for rectification the IN5408 was chosen. It has a peak reverse voltage of 150V.
For the capacitor the expected peak voltage is 12.7V which means that the peak - to - peak voltage will
be
Vp_p=2x12.7V
= 25.4V
So, a capacitor whose rating will be more than 25.4V must be used.
For the capacitance of the capacitor we consider the following:
LoadojectedVoltageRipplequired
VoltagePeakTPeriod
ceCapaci
PrRe
,
tan
The period is that for charging and discharging of the capacitor which is 0.002s for full wave rectifier.
Period T = 0.002s
Peak voltage = 12.7V
Required ripple voltage = 5% peak - to - peak voltage.
= 5/100 x 25.4 = 1.27V
Projected load = 8Ω
827.1
7.12002.0
,tan
CceCapaci = 0.0025
C = 0.0025 x10-6
F
For better smoothening, a capacitance of higher value can be used. Also, considering the available
capacitor in the market the 3300 micro farad capacitor was preferred. This gave rise to the use of 3300f-lF 35V
capacitors.
Stereo Stage
This is the stage where the input signal is processed. The audio input signal is fed directly to the stereo
stage, through the input devices. The audio signal is processed and filtered. The filtering is achieved by the use
of capacitors and resistors.
The stereo stage involves the Gain, Frequency (Treble) and Mid (Bass). The Frequency and Mid are to
perform the filtering job. At this juncture, it will be necessary to say something about filters.
Filters
The reactance of inductor and capacitors depend on the frequency of the a.c signal applied to them.
That is why they are known as frequency selective components. By using various combinations of resistors,
inductors and capacitors we can make circuits that have the property of passing or rejecting either low or high'
frequencies or bands of frequencies. These frequency selective networks which act on the : amplitude and phase
characteristic of the input a.c signals are called filters. Their performance is usually expressed in terms of how
much attenuation a band of frequencies that passed through them experienced. The attenuation is expressed in
terms of decibels (dB). Filters are circuits that are -able to select or reject signals according to their frequencies.
They are classified according to the band of frequencies which is passed or stopped.
Tone Circuit
The circuit below was designed for the tone circuit (low and high pass filters), which performed the
function of bass and treble respectively.
4. Design Of 16 Channel R.F. Mixer
www.iosrjournals.org 62 | Page
Figure 3.6: The Tone Circuit for the Audio Mixer - for Bass and Treble
Simply put the term audio means sound. The normal audio signal is of low level, that is, a signal of the
range of frequencies which our ears can hear. The range of human hearing extends from 300 to 3400Hz.
The constructed audio mixer accepts audio inputs (up to 16) and combined them together to give an
output. The output is monitored by the use of variable resistors (50KΩ).
The 50kΩ resistors were used as volume controls. In the stereo stage is the gain control (50KO variable
resistor). The input signal from the input socket goes directly to the gain control which in turn feeds the Bass
and Treble.
Note: Each channel of the stereo stage has its individual Gain, Treble and Bass controls.
In choosing components for the tone circuit, the Gain, Treble and Bass were considered. The Gain is to
have a frequency range of 2 - 20 KHz that for treble is 200Hz - 2 KHz and the Bass is to have a frequency range
of 20 - 200Hz.
The expression for frequency is given by
RC
f
2
1
For the Treble
R = 10KΩ = 10000Ω
C = 223 = 22 x 10-9
F.
and = 3.142
9
1010000142.32
1
f
= 723Hz. This is a value between 200Hz and2Khz.
For the Bass
R = 10K = 10000 ohms
C = 104 = 100 x 10-9
F
= 3.142
9
101001000142.32
1
f
= 159 Hz
This is a value between 20 - 200 Hz
For the Gain, considering circuit diagram of the stereo stage of the audio mixer the resistance R is 470
0 resistor in parallel with 1 OOK 0 resistor
From
100000
1
470
11
R
100000470
100000470
R
R = 467.8 ohms.
C = 473 = 47 X 10-9
F
9
108.467142.32
1
f
= 7238.7 Hz
This is a value between 2 - 20 KHz.
R1
R2
R3
R4
R5
IC1
C1 C3
C2
5. Design Of 16 Channel R.F. Mixer
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Varying the 50k ohms resistors (use) as the volume control, one can vary the frequencies thereby
changing the tone (i.e. the output sound) as desired.
Auxiliary Stage
To improve the final output (at the loudspeaker), an auxiliary stage was designed for the mixer. The
stage is fed directly from the output of the stereo stage via a resistor. Two auxiliary stages (A1 and A2) were
provided.
Volume Control Stage
There are two major controls in this stage, master volume control and master auxiliary control. The
master volume control is used to control all the volume at the same time. All the outputs of the stereo stage were
looped together and connected to a master volume control (50KΩ variable resistor).
As done by the master volume control, the same is applicable to the master auxiliary control. The
outputs of the auxiliary stage were looped together and connected to a master auxiliary control. The figure
below shows the block diagram of the stereo stage with Gain, Frequency (Treble) and Mid (Bass).
Figure 3.7: Block Diagram of the Stereo Stage
A simple block diagram of the audio mixer is as shown below:
Figure 3.8: Block Diagram of Audio Mixer
2 – 20kHz
200 – 2kHz
20 – 200Hz
Frequency
MID
To volume
control
Gain
Audio Input
Input
Device
Stereo
Stage
Level
Control
MVC Stereo
Output
Aux
Stage
MAC Aux
Output
EXT. AMP
EXT. L/S
6. Design Of 16 Channel R.F. Mixer
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Note
MVC - Master Volume Control
MAC - Master Auxiliary Control
Aux - Auxiliary
Ext - External
L/S – Loudspeaker
III. Conclusion
The 16 channel audio mixer is tested by connecting it to an external amplifier which is in turn
connected to loudspeakers. The connection of the amplifier is to the output of the mixer. The heat generated is
very low compared to that of an amplifier. As a result of this a wooden casing can be conveniently used as the
case. It should be connected to an amplifier for heavy load.
References
[1]. Amos, S.W.; Amos R. S. (1999): Newness Dictionary of Electronics, Elsevier.
[2]. Henderson, B. C. (1983):“Predicting IntermodulationSuppression in Double-Balanced Mixers,” Watkins-Johnson Company
Technical Notes. Vol. 10, No. 4.
[3]. Maddock R. J. and Calcutt D. M. (1993): Electronics for Engineers Second Edition, McGraw Hill.
[4]. Marki F. andMarki C., (2010): Mixer Basics Primer, A Tutorial for RF& Microwave Mixers,Marki Microwave, Inc.
[5]. Mixer Evolution, The Balanced Mixer Family Circle.Application
Note.http://www.markimicrowave.com/menus/appnotes/balanced.pdf.