The circuit diagram of Mini 2 W amplifier has been published here. The core part of this circuit is the IC TDA 7052 from Philips Semiconductors. The IC TDA7052 is a mono output amplifier. This IC has some features like 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. This amplifier IC has an internally fixed gain of 40 dB. Bridge-Tied-Load principle (BTL) is used by TDA7052 to compensate the reduction of output power due to low voltage supply.

The IC TDA7052 is an 8-lead DIP and is mainly designed for battery-operated portable audio circuits. Volume control in this circuit is done by potentiometer R1 (4.7 K). Capacitors C1 and C2 are used for supply voltage elimination when supply source is battery eliminator.

Circuit Diagram

Mini Amplifier Circuit

Notes

• Use a good quality PCB or common board to assemble this circuit
• For operations using a battery C1 and C2 are not necessary
• IC TDA 7052 can provide  an output  of around 1 to 2 W  into an 8 Ohm load with a power supply of 6 V
• This amplifier can operate even from a 3V Mercury button cell and this makes it ideal for battery operated gadgets.

Circuit diagram of 19 Watt amplifier using LA 4440 has been published here. This amplifier circuit is based on the IC LA 4440 developed by Sanyo. In this circuit, amplifier IC LA 4440 acts as bridge amplifier. This IC has an extra feature that is protection against thermal, over voltage and short circuits. Adequate heat sinks should be provided for this IC in PCB.

12 V DC power supply is used for powering this circuit. The power supply used should be able to deliver a current of 3A at least. This IC can with stand up to 25 V but it is safe to use up to 16V. A 4 ohm speaker is used here as load. This speaker load can be 8 ohm but in that case output power will become half of that with 4 ohm speaker.

Circuit Diagram

Amplifier using LA 4440 ic

LA 4440 Specifications

la 4440 specifications

Notes

• Use a good quality PCB to assemble components for this circuit. Carefully understand the specifications of LA 4440 given above.
• This amplifier can deliver a 19 W Rms on a 4 Ohm speaker.
• The IC LA 4440 also incorporates an audio muting function but it is not required in this circuit.

The following circuit diagram represents 3 W stereo amplifier. This circuit is based on the IC MAX 7910. This particular IC has some added features like thermal overload protection. This amplifier IC is a stereo amplifier IC. This IC has another important advantage that it can operate from a single 4.5 to 5.5 V power supply. This feature makes it ideal for its application in hand held devices.

This amplifier circuit is suitable for small power audio devices such as radio sets and portable CD players. 5 V DC power supply is used for powering the circuit. 6V battery with an IN 4007 diode series to the positive terminal of it can also be used instead of 5 V DC supply. The circuit will get a supply voltage approximately 5 V after 0.7 V voltage drop across diode.

Circuit Diagram

Simple 3 Watt stereo amplifier circuit

Notes

• Use a good quality PCB or common board to assemble this circuit.
• The circuit is designed strictly as per the datasheet and found to be working properly.
• The MAX 9710  stereo audio power amplifier IC is can deliver  3Watts  of output to 4 Ohm loads

The circuit diagram of 10W amplifier using TDA 2003 has been published here. This simple amplifier circuit is based on a central IC TDA 2003 developed by SGS Thomson. This IC has some advanced features like short circuit protection, thermal overload protection, low harmonic and cross over distortions etc. This circuit is designed after the datasheet of IC TDA 2003 provided by the vendor.

In this circuit, gain of the amplifier is determined by the resistors R2 (220 ohm) and R3 (2.2 ohm). The upper cut off frequency is determined by capacitor C3 (39 nF) and resistor R1 (39 ohm). The stability of the amplifier at high frequencies is accomplished by capacitor C6 () and resistor R4 (1 ohm). Input DC decoupling is done by capacitor C7 (10 uF) and output is coupled to the speaker by C5 (100 uF).

18V DC supply is used in this circuit to give power. Adequate heat sinks must be provided for TDA 2003. This amplifier delivers maximum power of 10W to a 4 ohm load at 18V supply. This IC has an advantage of working in a range of supply voltage from 12 V to 18V. In order to get maximum performance of this circuit on PCB, input and output grounds must be properly decoupled.

Circuit Diagram

IC TDA 2003 Amplifier

Notes

• Use a good quality PCB to assemble this circuit.
• IC TDA 2003 is suitable for car audio systems.
• Adequate heat sink should be provided for TDA 2003.

The circuit diagram given below represents 40W audio amplifier. This 40W power amplifier circuit is designed using IC TDA 2030 and two transistors as main components. The IC TDA 2030 is the core part of this circuit because it plays the main role in voltage amplification. The job of current amplification is done by the two transistors. Adequate heat sinks should be provided for IC and both transistors.

The input signal is fed to the non- inverting terminal (pin 1) of TDA 2030 IC through the decoupling capacitor C5 (470 nF). When voltage amplification is performed by TDA 2030, the power supply current to IC changes with respect to the variation in the input signal. The variations in positive and negative supply pins of the IC are coupled to transistors Q1 (BD 712) and Q2 (BD 711). These transistors are connected complementary to each other in circuit so that they perform current amplification.

Power supply for the circuit can be 12V to 40V. Use 40V supply and 4 Ohms speaker for maximum output. To optimize the circuit performance, input and output grounds must be properly decoupled.

Circuit Diagram

40 Watts Audio Amplifier Using TDA 2030

Notes

• Use a good quality PCB to assemble components for this circuit.
• Make PCB tracks broader through which high current flows.

The circuit diagram of 6W amplifier using TA 7222AP is given here. This circuit uses integrated audio amplifier IC TA 7222AP as its central part. This is a famous and widely used amplifier IC developed by Toshiba. The unique features of this IC make it suitable for amplifier circuits. The features include short circuit protection, thermal protection, high ripple rejection, low distortion, muting function etc. A suitable heat sink should be provided for this IC to operate safely.

12V DC power supply is used for powering this circuit. The audio amplifier IC TA 7222AP can deliver a maximum output power of up to 5.8 Watts to a 4 ohm load if the supply voltage is 12V. This amplifier is well suited for car radio applications because it can operate in a range of voltage, i.e. from 8V to 12V. In order to get maximum desired performance for this circuit, provide separate ground for input and output.

Circuit Diagram

6 watt amplifier

Notes

• Us good quality Vero board. To assemble components for this particular circuit.
• The speaker K1 used here can be 4 ohm.

The circuit diagram of Pocket headphone amplifier has been given here. The core part of this circuit is the operational amplifier IC OPA 134 developed by BURR-BROWN Semiconductors. In addition to this the circuit contains some passive components also.

The IC OPA 134 is used in this circuit as a non-inverting amplifier. High input impedance for this IC is provided by the FET biased input stage and this also makes this IC suitable for audio applications. A switch S1 is used in this circuit to accomplish circuit ON/OFF. An indicator LED shows whether the circuit is powered or not. Resistor R2 (100K) and capacitor C1 (0.1 uF) connected to the non-inverting terminal (pin 3) of OPA 134 is a high-pass filter network having a corner frequency approximately 15 KHz. To reduce noise and distortion in output, a load resistance R5 (20 ohm) is used. This load resistance also stabilizes the virtual ground. The output of this circuit is DC coupled. The variable resistor port R1 (47K) is the volume controller of this amplifier circuit.

Split power supply of +/- 4.5 V is required for IC OPA 134. This obtained from a 9V PP3 battery using a network composed of resistors R6 (10K), R7 (4.7K), R8 (4.7K) and capacitors C2 (220 uF), C3 (220 uF).

Circuit Diagram

Simple Pocket Headphone Amplifier Circuit

Notes

• Use a good quality PCB to assemble components.
• Sound sources like MP3 players, I Pods, mobile phones etc can be plugged in this circuit.
• IC OPA 134 is specially designed for audio applications.

Automatic cooler fan for amplifiers is a circuit introduced for the purpose of saving power in amplifier circuits. This circuit switches ON and switches OFF the cooler fan of heat sink according to its temperature. The cooler fan will turn ON when heat sink temperature exceeds a certain value and will turn OFF temperature become lower than a certain value. Automatic cooler circuit does it always so that effective working of cooling fan occurs and that saves power.

In this circuit thermistors are used as temperature sensors. Here negative temperature coefficient thermistor (NTC) is used. NTC means as temperature increases the resistance of NTC thermistor decreases. Resistor R2 in circuit diagram is an NTC thermistor. Here LM311 IC is used as a comparator which is having an inverting (pin 3) and non-inverting (pin 2) input pins. The junction of R1 and R2 is connected to pin 3. At pin 2 a reference voltage is given using resistor R3. The comparator compares voltage at its inverting and non-inverting terminals. When voltage at inverting terminal becomes less than that at non inverting terminal, the output of comparator becomes high. This will turn ON transistor Q1 which triggers relay and cooler fan will turn ON. Fan will be turned off when voltage at inverting terminal becomes higher than non-inverting terminal.

12 V DC supply is used as power supply in this circuit. The relay K1 can be a 12V, 200 ohm, SPST relay. Calibration of this circuit can be done by adjusting R3.

Circuit Diagram

Automatic Cooler Fan Circuit for Amplifiers

Notes

• Use Vero board to assemble components.
• Diode D1 is a freewheeling diode.
• LED D2 acts as an indicator, it will glow when fan is ON.

4×15 watt power amplifier consists of four channels of amplifiers. The core part of the circuit is 15W BTL X 2 channel audio power amplifier IC TA 8215 developed by Toshiba. In this power amplifier circuit, two TA 8215 ICs are used. This is for obtaining four channels that is two channels from each IC. TA 8215 is an IC with power amplifier stages and preamplifier integrated inside it. Pins 7 and 19 are Vcc and pins 13 and 14 are ground of power amplifier stage. Vcc and ground pins should be connected to positive supply and ground respectively. Pin 9 is the Vcc of internal pre-amplifier and Pin 5 is its ground. Vcc is connected to positive supply and ground pin to ground through a 10 ohm resistor which separates input ground from common ground and this improves noise rejection.

In this circuit power supply decoupling is accomplished by 100 uF (C6 and C20) capacitor. High frequency stability in this circuit is achieved by the resistor network connected to the output line of each of the amplifier. Volume controller in each channel is the variable resistors of 10k (R3, R4, R12 and R13). The power supply required for this amplifier is single 12 V DC supply. The maximum output power delivered from each channel of this amplifier is 15 W to a 4 ohm speaker and hence the name 4×15 W power amplifier.

Circuit Diagram

4x15 Watt Power Amplifier Circuit

Notes

• For obtaining optimum sound quality assemble above circuit on a good quality PCB
• The applications of this circuit have a wide range such as car audio systems, home theater systems, personal audio systems, public address systems etc.

The circuit of 2×32 Watts stereo amplifier consists of two channels. In both the channels the central component is the IC TDA 2050 V developed by ST Microelectronics. The audio input signal is given to each of the channels in non-inverting input pin of IC TDA 2050V. For decoupling purpose, capacitor 1 uF (C1 and C8) is connected so that input can be given through it as shown in the circuit diagram.

The gain of the amplifier in each channel is determined by the resistors 22k (R1 and R5) and 680 ohm (R2 and R6). The value of gain is the ratio of 22K and 680 ohm. To improve the frequency response of the amplifier, a network called Zobel network is used in this circuit. Here the Zobel network is the combination of 2.2 ohm (R4 and R8) resistor and 0.47 uF (C3 and C14) capacitor that are connected in series between the amplifier output and ground in both the channels. By the effect of Zobel network, impedance of the speaker appears as resistive load and that improves frequency response of the amplifier.

The central part of the circuit TDA 2050V IC is an integrated monolithic 32 watt class B audio amplifier. It has some extra features like short circuit protection, low distortion, thermal protection etc. and it is available in Pentawatt package. Proper heat sink should be provided for this IC in PCB. Power supply required for this circuit is 18 V DC dual supplies. In order to get maximum output power, the input required is 200m Vpp RMS. Volume control is done by 10K pots connected at input lines. Assembling this circuit on a good quality PCB will give the desired output.

Circuit Diagram

Simple stereo amplifier circuit