Schematic & Wiring Diagram

This is the schematics of a simple low cost mic mixer that can be assembled from the components in your junk box. This two channel mike mixer is designed for handling high impedance dynamic microphones. Transistor Q1 can be any general purpose pnp transistor like BC177 or BC558.

How ever better the transistor quality better the performance. Resistors R2 and R3 can be used for the level control of input signals.

Notes

• All capacitors are of ceramic type.
• Always use a battery two reduce noise .
• Avoid using power transistors as Q1. This is because power transistors have high leakage current and it adds to the noise which is not suitable for our purpose here

source: circuitstoday.com

This low cost amplifier is simple and give you good result. Here the op-amp used is uA 741 which produces the required gain.The four transistors are wired as complementary Darlington’s which produces the drive for the speaker.

The voltage drop across the resistors R2 and R3, are used as the input of the Darlington pairs . As the input current to the op-amp depends on the level of the signal op amp is amplifying the voltage drop across the resistors R2 and R3 will be proportional to the input signal. These voltage drops are given to the base of Darlington pairs. The amplification is stabilized as a result of the negative feedback from the junction of collectors of Q2 and Q4. The theory may seem little awkward for you. But its working good.cSuch a simple but stable circuit as this can produce a reasonable output of 12W on a 4 Ohm speaker.

This circuit diagram is very simple, very easy to build and will be great idea for newbie or student project.

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 heatsinks 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 no necessary.

Here is the circuit of a 2X12 watt HiFi stereo audio amplifier circuit using IC TDA 2616 from Phillips. A quiet simple and robust circuit using very less components. This makes the circuit ideal for a portable power amplifier. The circuit delivers 12 W power on 8 Ohm speaker for each channel at +/- 12 V dual supply.

The TDA2616 is a stereo power amplifier IC comes in a 9-lead single-in-line (SIL9) plastic power package (SOT131). This IC is specially designed for mains fed amplifier circuits, such as stereo radio, tape and television . The IC has good gain balance of both channels and Hi-fi in accordance with IEC 268 and DIN 45500 standards. Also the IC TDA 2616 has special inbuilt circuit for the suppression of noise signals at the inputs, during switch-on and switch-off. This prevents click sounds during power on and power off.

Notes.

• All capacitors except C10 & C9 are ceramic.
• All capacitors must be rated 50V.
• Use a well regulated and filtered +/- 12 V dual power supply that is able to provide at least 2 A continuous current.

TDA 2616 Pin assignment & layout.

source: circuitstoday.com

For an amplifier with 150 Watt in power, may be this is the cheapest one . This amplifier circuit built based on two Darlington power transistors TIP 142 and TIP 147, this circuit can deliver a blasting 150 W Rms to a 4 Ohm speaker.

TIP 147 and 142 are complementary Darlington pair transistors which can handle 5 A current and 100V, famous for their ruggedness. Here two BC 558 transistors Q5 and Q6 are wired as pre amplifier and TIP 142, TIP 147 together with TIP42 (Q1,Q2,Q3) for driving the transistors. This circuit is designed so rugged that this can be assembled even on a common board or even by pin to pin soldering. The circuit can be powered from a +/-45V 5A dual power supply. You must try this circuit. Its working great.

Notes:

• Remember TIP 142 and 147 are Darlington pairs. They are shown as coventional transistors in figure for ease. So don’t get confused. Even though each of them have 2 transistors, 2 resistors and 1 diode inside, only three pins, base emitter and collector are coming out. Rest are connected internally. So its quite OK to assume each of them as transistor for ease.
• Use a well regulated and filtered power supply.
• Connect a 10K POT in series with the input as volume control if you need. Not shown in circuit diagram.

This very simple circuit is ideal for small power audio applications like portable CD players or radio sets.The circuit is designed strictly as per the datasheet and found to be working great.

The MAX9710 a stereo audio power amplifier IC capable of delivering 3Watts of out put to 4 Ohm loads. MAX9710 can be operated from a single 4.5V to 5.5V power supply , makes it ideal for hand held applications.The IC also features thermal overload protection.

Notes:

• Use a 5 V DC power supply for powering the circuit.
• If you want to use a battery ,then use a 6V battery with a IN 4007 diode series to the positive terminal of it.The diode will drop 0.7 V and the IC will get the rated ~5V.This is just a safety recommendation .
• Assemble the circuit on a good quality PCB or common board.

source: circuitstoday.com

Here the simple and low cost audio amplifier schematic diagram. The circuit is ideal for a pocket radio or other hand held audio equipments.

The first part of the circuit here is a preamplifier consisting of transistor Q1(2N2222). The collector of the Q3 is coupled to the base of Q2 (2N2905A),which forms a complementary symmetry pair with Q3 (2N3053). The amplified signal is available at the junction of emitter of two transistors.

Notes:

• For Q1 you can try with any general purpose NPN transistors like BC107, BC148,etc.
• For Q2 and Q3 you can try any complimentary power transistors. The result may vary slightly. No problem.
• The can be also powered from a well regulated and filtered 9V DC power supply.

source: circuitstoday.com