shared wiring: audio

Showing posts with label audio. Show all posts

Tuesday, July 9, 2013

Build a 25W Bridge Audio Amplifier with TDA2005

This is the 25W bridge audio amplifier built using single power IC TDA2005. Actually, the TDA2005 is a stereo power amplifier chip. It has two input channels and two output channel and delivers about 10W power output for each channel, since it connected in bridge mode then it will delivering up to 25W audio output. Take a note that the speaker terminals should not conected to the ground and mount the IC on the heatsink to prevent overheating.

25W Bridge Audio Amplifier with TDA2005 Circuit Diagram

Parts List:
R1 = 120K?
R2,5,6 = 1K?
R3,4 = 12?
R7,8= 1?
C1,5,7 = 220uF/25V
C2,10,11 = 100nF
C3,4 = 2.2uF/25V
C6,8 = 100uF/25V
C9 = 10uF/25V
IC1 = LM2005M / TDA2005

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Sunday, July 7, 2013

Cell Phone Controlled Audio Video Mute Switch

This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily available cell-phone holder with some mi-nor alterations or fabricate it yourself as shown in Fig. 1.

Fig. 1: Proposed cell-phone holder

The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.

Fig. 2: The circuit of the cell phone-controlled audio/video mute switch

When the cell phone is in its holder, LDR1 does not receive any light from white LED1 and its resistance is high. As a result, the voltage at pin 2 of IC1 re-mains high to provide a low output at pin 3. The low output of IC1 activates relay RL1 and the audio/video system gets power supply via its N/O contacts. LED3 glows to indicate that the audio/video system is ‘on.’ When the handset is taken off the holder, light rays from LED1 fall on LDR1 and its resistance decreases.

As a result, the voltage at pin 2 of IC1 de-creases to provide a high output at its pin 3. The high output of IC1 deactivates relay RL1 and the audio/video system does not get power supply. LED2 glows to indicate that the audio/video system is ‘off.’ Preset VR1 is used to control the sensitivity of the circuit. Zener diode ZD1 is used for protecting white LED1 from the higher voltage. The circuit works off a 12V car battery. Switch S1 can be used to manually switch on/off the audio/video system.

http://streampowers.blogspot.com/2012/06/cell-phone-controlled-audiovideo-mute.html

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Friday, May 31, 2013

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Wednesday, May 29, 2013

The Audio Video Distribution Amplifier

With the amount of equipment in home entertainment centers today the need to be able to vary the gain of the audio or video signal is needed. I found this particular circuit helpful when used in conjunction with the Universal Descrambler and a Stabilizer circuit I built for making copies of video tapes. It not only allowed me the ability to fine tune the video strength it also helped me increase the recorded audio which typically becomes poor when making tape copies. Circuit operation is straight forward for amplifier circuits. The second channel for the audio amplifier is made up of the same components except the other half of IC1 is used. Pin 6 & 5 are inputs and 7 is the output.

Circuit Diagram

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Friday, April 12, 2013

Condenser Mic Audio Amplifier

The compact, low-cost condenser mic audio amplifier described here provides good-quality audio of 0.5 watts at 4.5 volts. It can be used as part of intercoms, walkie-talkies, low-power transmitters, and packet radio receivers. Transistors T1 and T2 form the mic preamplifier. Resistor R1 provides the necessary bias for the condenser mic while preset VR1 functions as gain control for varying its gain. In order to increase the audio power, the low-level audio output from the preamplifier stage is coupled via coupling capacitor C7 to the audio power amplifier built around BEL1895 IC.BEL1895 is a monolithic audio power amplifier IC designed specifically for sensitive AM radio applications that delivers 1 watt into 4 ohms at 6V power supply voltage. It exhibits low distortion and noise and operates over 3V-9V supply voltage, which makes it ideal for battery operation. A turn-on pop reduction circuit prevents thud when the power supply is switched on. Coupling capacitor C7 determines low-frequency response of the amplifier. Capacitor C9 acts as the ripple-rejection filter.

Condenser Mic Audio Amplifier Circuit Diagram

Capacitor C13 couples the output available at pin 1 to the loudspeaker. R15-C13 combination acts as the damping circuit for output oscillations. Capacitor C12 provides the boot strapping function. This circuit is suitable for low-power HAM radio transmitters to supply the necessary audio power for modulation. With simple modifications it can also be used in intercom circuits.

Source: http://www.ecircuitslab.com/2011/06/condenser-mic-audio-amplifier-circuit.html

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Thursday, April 11, 2013

Simple Mini Audio Amplifier circuit

Description

Here is a simple and humble 2 Watts mini audio amplifier circuit suitable for small pocket radios and other portable audio gadgets.The circuit is based on Phillips Semiconductors IC TDA 7052.The amplifier can be run even from a 3V Mercury button cell.This makes it ideal for battery operated gadgets.

The IC TDA7052 is a mono output amplifier coming in a 8-lead DI package (DIP). The device is mainly designed for battery-operated portable audio circuits. The features of TDA 7052 include ,no external components needed, no switch-on or switch-off click sounds , great overall stability ,very low power consumption(quiescent current 4mA) , low THD, no heat sinks required and short-circuit proof.

The gain of TDA 7052 is fixed internally at 40 dB. . To compensate the reduction of output power due to low voltage supply the TDA7052 uses the Bridge-Tied-Load principle (BTL) which can provide an output of around 1 to 2 W Rms(THD = 10%) into an 8 Ohm load with a power supply of 6 V.

In the circuit the potentiometer can be used to control the volume. Capacitor C1 and C2 are meant for filtering the supply voltage if a battery eliminator is used as supply source. For operations using a battery C1 and C2 are not necessary.

Mini Audio Amplifier Circuit Diagram with Parts List:

Notes.

Assemble the circuit on a good quality PCB or common board .
If you are a little expert, you can assemble the circuit in a match box including the speaker.

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Monday, April 1, 2013

Simple 3 Channel Audio Splitter

Simple circuitry, Passive high-quality amplification and distribution

This circuit is suitable to amplify and distribute the audio signals. The input audio signal is applied to the J1 and after passing through the P1, It is buffered and amplified by the IC1 prepared to redistribute. It has 3 outputs to drive 3 audio lines with 300 ohms impedance.

3 Channel Audio Splitter Circuit diagram :

Parts:

J1 = RCA Socket (See Notes)
P1 = 100K-Potentiometre
R* = 10K-100K
R1 = 560K
R2 = 1K
R3 = 2.2K
R4 = 2.7K
R5 = 2.7K
R6 = 330R
R7 = 330R
R8 = 330R
C1 = 100uF-25V
C2 = 100uF-25V
C3 = 100uF-25V
D1 = BZX79C18
D2 = BZX79C18
Q1 = BC337
Q2 = BC327
IC1 = NE5532-34

Notes:

J1 will be RCA Audio input female socket.
R* is on your choice it can be choose between 10K to 100K resistor.
Output capacitor’s value is between 100uf to 470uf and power handling is 25V to 50V.
You can power up this circuit via +12V/-12V regulated supply but you have to remove following parts Q1-Q2-C2-C3-D1-D2.
Maximum power ratings +35V/-35V

Source : www.ecircuitslab.com/2011/05/three-channel-audio-splitter.html

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Sunday, March 31, 2013

Audio Amplifier Output Relay Delay

This is a simple circuit which I built to one of my audio amplifier projects to control the speaker output relay. The purpose of this circuit is to control the relay which turns on the speaker output relay in the audio amplifier. The idea of the circuit is wait around 5 seconds ofter the power up until the speakers are switched to the amplifier output to avoid annoying "thump" sound from the speakers. Another feature of this circuit is that is disconnects the speaker immediately when the power in the amplifier is cut off, so avoiding sometimes nasty sounds when you turn the equipments off.

Parts
C1 = 100 uF 40V electrolytic
C2 = 100 uF 40V electrolytic
D1 = 1N4007
D2 = 1N4148
Q1 = BC547
R1 = 33 kohm 0.25W
R2 = 2.2 kohm 0.25W
RELAY 24V DC relay, coil resistance >300 ohm

Circuit operation:

Then power is applied to the power input of the circuit, the positive phase of AC voltage charges C1. Then C2 starts to charge slowly through R1. When the voltage in C2 rises, the emitter output voltage of Q1 rises together with voltage on C2. When the output voltage of Q2 is high enough (typically around 16..20V) the relay goes to on state and the relay witches connect the speakers to the amplifier output. It takes typically around 5 seconds after power up until the relay starts to conduct (at absolute time depends on the size of C2, relay voltage and circuit input voltage). When the power is switched off, C1 will loose its energy quite quickly. Also C2 will be charged quite quickly through R2. In less than 0.5 seconds the speakers are disconnected from the amplifier output.

Notes on the circuit:

This circuit is not the most accurate and elegant design, but it has worked nicely in my small home-built PA amplifier. This circuit can be also used in many other applications where a turn on delay of few seconds is needed. The delay time can be increased by using bigger C2 and decreased by using a smaller C2 value. Note that the delay is not very accurate because of simplicity of this circuit and large tolerance of typical electrolytic capacitors (can be -20%..+50% in some capacitors).

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