The circuit of the amplifier with TDA7294 was a big hit among our readers, so bring more than this version of the amplifier with TDA 7294 “Brutus,” this is an application bridge to the tda7294 that can provide up to 170 Watts @ 8ohms, 38 VDC.
The integrated circuit TDA7294 developed by SGS Thompson (www.st.com), allows you with little money, a lot amp complete, it is designed as audio amplifier in class AB and is ideal for use in systems Home Theater High-quality amplifiers and easy assembly. He is able to work with loads (speakers) of 4, 8 and 16 Ohms. He is capable of delivering 100 Watts @ 4ohms, VS = +-29V, 100 Watts @ 8ohms, Vs = +-38V. The total distortion is only 0.1% PO = 0.1 to f = 50 Watts 20Hz to 20KHz.
In this version of Bridge or Bridge amplifier, keep in mind the impedance of the speakers! 8 Ohms is the minimum recommended is 16 ohms using only voltage up to +-38Volts.
R = 8 Ohms VS =+-25V, PO = 150 Watts
R = 16 Ohms Vs = +-35V, Po = 170 watts
You can use up to 4 Ohms, but the system of IP protection will take action and reduce the maximum power for a safe bet!
Diagram of Brutus – Schematic circuit amplifier with TDA 7294 – 170 Watts x2 – click for enlarge
The circuit is divided into two main parts of the power supply and power amplifier.
Power supply for Brutus – The power consists of a transformer of 250VA @ 22-0-22 to 28-0-28, The bridge rectifier should be a GBU15G, the capacitors of the source can be provided to 4700μF/63V 22000μF / 63V, if you use a source of maximum + -28 volt operating voltage of the capacitor can be 50V. There are also two capacitors and two resistors polyester, the function of these resistors is to unload the large electrolytic capacitors, when disconnecting the circuit. The fuses are to give additional protection for the circuit, do not forget to add a fuse before the transformer.
Power Amplifier – Part of the amplifier is configured to work in stereo bridged using 4 integrated circuits, resistors R4, R7 (R) and R20, R17 (L) determine the gain of the circuit with these components is configured to 30 dB. The circuit mute / stand-by is connected directly to the DC circuit, if you can add a switch to toggle between silent and active. The input impedance is determined by resistors R9 and R22.
Suggested PCB mounting Brutus – bridged stereo amplifier 2 x 170 Watts (300 + watts total) – click in images for enlarge
The printed circuit board assembly is suggested for this single-sided, mainly to facilitate the lives of beginners … but if there is one face has Jumpers! It should connect pieces of wire, connecting the dots in red is the source + VCC.
List of material to mount the amplifier in bridged Brutus
|Resistor’s 1/4 Watts 5%|
|R1, R2||4k7 – Yellow, Violet, Red, Gold|
|R3, R4, R16, R17||680 – Blue, Gray, Brown, Gold|
|R5, R6, R7, R18, R19, R20||22k – Red, Orange, Orange, Gold|
|R8, R9, R21, R22||12k -Brown, Red, Orange, Gold|
|R10, R12, R23, R25||27k – Red, Violet, Orange, Gold|
|R11, R13, R24, R26||100k -Brown, Black, Yellow, Gold|
|R14, R15, R27, R28||47k – Yellow, Violet, Red, Gold|
|C1, C8, C11, C13, C19, C21||1µF/100V – Polyester film capacitor|
|C2, C10||100nF/250V – Polyester film capacitor|
|C3, C4, C6, C7||10000µF/63V – Polarized electrolytic capacitor|
|C5, C9||1000µF/63V – Polarized electrolytic capacitor|
|C12, C14, C15, C16, C17, C18, C20, C22, C23, C24, C25, C26||22µF/63V – Polarized electrolytic capacitor|
|IC1, IC2, IC3, IC4||TDA7294V – Integrated Circuit Audio Amplifier|
|D1, D2, D3, D4||1N4148 – semiconductor diode|
|B1||GBU15G – 400V/15A rectifier or equivalent|
|F1, F2||8 Amp Fuse|
|IN||Audio input connector|
|L-OUT||Connector Left Channel audio output|
|R-OUT1||Connector Right Channel audio output|
|TRAFO||Connector to the transformer 22-0-22 to 28-0-28 (16 Ohms)|
|Solder, wire, printed circuit board, heat sink for integrated, bolts, box, etc.|
Download the PDF files to mount stereo amplifier Bridge: Silk Screen, PCB, PCB component side, Silk screen, TDA7294 Eagle Library, TDA7294 Datasheet
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