Make a 200w HiFi mono amplifier with signal gain boost option

In this project I will take you through making a 200w HiFi mono amplifier with signal gain boost option.

Hello everyone, today in this tutorial we will see how to make a bass and high bass amplifier circuit using TDA7294Ic. The TDA series of Texas Instruments is known for its Hi-Fi performance. Therefore, very high power can be obtained from this amplifier circuit. This amplifier works on a dual power supply, that is why we need a center tapped 24-0-24 volt 5 amp transformer to get better sound quality.

Here today we will design only one channel (mono) and open it to stereo using the same circuit. But we use the bridge method in mono, which will provide 200 watts RMS to a single subwoofer. This is a class AB amplifier, so we need a good heat sink and a stable input power supply (high quality DC-filter circuit using).

Supplies

Welding equipment

Propanol (PCB cleaner)

power supply

transformer

heat sink

Screws and nuts bolts

Speaker 4ohm 200watts

Heat sink compound

Step 1: TDA7294 Pinout

1) High input voltage range (+-40v)

2) Mute/Standby function'

3) No switching noise

4) Short circuit protection

5) Thermal shutdown

6) Low noise

Finally, we will make a fully working PCB and order it from our sponsor JLCPCB, a top PCB manufacturing company in China (5 PCBs for only $2).

Step 2: Components Used

1) TDA7294 integrated circuit

2) 1K resistor

3) 22k resistor

4) 10k resistor

5) 47uF 50V capacitor

6) 100uf 50volt capacitor

7) 1N4007 diode

8) 1000uf capacitor

9) 47K potentiometer

10) 100nf polyester film capacitor

The circuit is same as given in the datasheet, after changing the component placement, the simplified circuit diagram of the device is shown below.

Step 3: Circuit Diagram

Two TDA7294Ic are bridged together to provide 200 watts of RMS power. I have also added a gain pot for loudness and powerful performance. This will increase the strength of the input signal or you can say pre-amplify the input. This circuit is good for dual channel dual voltage. Check the power supply section from here.

Also, use 8 ohm speakers in bridge mode for best output and use a 24-0-24 power supply. Only the original version of this IC has over-temperature, short-circuit and over-temperature protection.

Step 4: Towards a Professional Look

I can design PCBs at home, but single layer boards with too many traces are impossible. The only reliable solution I could find is JLCPCB, a prototype PCB service. They offer 5 double layer PCBs for $2. If you sign up using this link, you will receive a free coupon worth $27 and other newcomer bonuses.

I gave my Gerber files to JLCPCB and got these amazing blue PCBs in 7 days. Also, you can choose any color combination and surface finish. My one was made with tin spray and has a thickness of 1.2mm.

Step 5: Gerber Files

Step 6: Assembly

I unboxed the PCB and started with the basic PCB, resistors, diodes and capacitors. I soldered the audio ic and other small components as per the list above.

The circuit is completely done, we need a good big heat sink with this amplifier. You can also add active cooling methods such as fans etc. Make sure to apply heat sink compound between the heat sink and the IC. This will create good thermal contact.

If you use the circuit in stereo or bridge mode, please add an insulating mica sheet behind these ICs. This way we can prevent the aluminum heat sink from shorting.

Step 7: Power Supply

The circuit can draw 200 watts from the mains, we need a good transformer that can provide dual channel power. I am using my toroidal transformer which can provide 24v and 12volts@5amperes.

I made this filtering circuit to test all my big amplifiers. This is a 10 amp power supply that can deliver up to 50 volts. Get all the info about this filtering power station from here.

Currently, we are only developing one 200w channel, but in the future we will also make dual channels, one for the speaker and the other for the subwoofer.