The TDA 7294 can be used in stereo mode (2 x 80Watts) or mono bridge mode (1x 180 Watts), to do this configuration simply set up 4 jumpers. To facilitate assembly the circuit has a power supply included. The power supply is simple symmetrical type with a bridge rectifier, capacitors being two large electrolytic, from 4.700μF to 12.000μF/50v. The recommended transformer is 12-0-12 at 25-0-25 / 5A, depending on the quality of the transformer recommended if a minimum of 6 Amperes current. Of course with a smaller transformer the power will be smaller as well as the current.
The TDA7294 is a monolithic integrated circuit in Multiwatt15 package, intended for use as audio class AB amplifier in Hi-Fi field applications (Home Stereo, self powered loudspeakers, Topclass TV). Thanks to the wide voltage range and to the high out current capability it is able to supply the highest power into both 4Ω and 8Ω loads even in presence of poor supply regulation, with high Supply Voltage Rejection. The built in muting function with turn on delay simplifies the remote operation avoiding switching on-off noises.
Another application suggestion is the BRIDGE configuration, where two TDA7294 are used, In this application, the value of the load must not be lower than 8 Ohm for dissipation and current
capability reasons. A suitable field of application includes HI-FI/TV subwoofers realizations.
In stereo, all jumpers must be open and the speakers are plugged into connectors Lout and Rout and audio input connectors in the Lin and Rin. In the amplifier in bridge mode all jumpers should be closed and the audio output Lout is (+ the speaker) Rout (- the speaker) and audio input will be Lin, Rin will be shorted to ground via JB2.
The main advantages offered by this solution are:
– High power performances with limited supply voltage level.
– Considerably high output power even with high load values (i.e. 16 Ohm).
With Rl= 8 Ohm, Vs = ±25V the maximum output power obtainable is 150 W, while with Rl=16Ohm, Vs = ±35V the maximum Pout is 170 W.
In bridge mode the manufacturer does not recommend using with speakers with impedance less than 8 Ohms.
In this circuit the mute / stand-by switch has been removed, but if you prefer, you can add it, the assembly is simple with a suggested circuit board.
The integrated circuit body should be insulated from the heatsink using mica or plastic thermal pad to insulate the screw.
Circuit of dynamic amplifier using tda 7294 – 180Watts bridge or stereo 2 x 80Watts – Click to enlarge
Suggested printed circuit board (PCB) for circuit dynamic audio amplifier with tda7294
|Resistors 1/4 Watt 5%|
|R1,R3,R7,R9,R13||22k – Red, Red, Orange, Gold|
|R2,R8||680 – Blue, Gray, Brown, Gold|
|R4,R10||100k – Brown, Black, Yellow, Gold|
|R5,R11||27k – Red, Violet, Orange, Gold|
|R6,R12||47k – Yellow, Violet, Orange, Gold|
|R14, R15||4.7K – Yellow, Violet, Red, Gold|
|C1,C3, C10, C11, C16, C17||100nF (104) / 100V – Ceramic Capacitor|
|C2,C4||4.700µF a 12.000µF/50v – Electrolytic capacitor|
|C5,C7,C8,C9,C13,C14,C15,C18||22µF/50v – Electrolytic capacitor|
|C6,C12||1µF /100V or 250V – Polyester Capacitor|
|C19, C20||220pF /100V – Ceramic Capacitor|
|CI1,CI2||TDA7294 – Integrated circuit|
|D1,D2||1N4148 Semiconductor diode|
|B1||GBU15G Or equivalent – Bridge rectifier|
|Led1, Led2||Red Led 5MM|
|Power||Terminal block connector 2 screws – Power supply connector|
|LOUT||Terminal block connector 2 screws – Left Audio Output (Stereo mode) or (+) bridge mode|
|LIN||Terminal block connector 2 screws – Right Audio Input (Stereo mode) or input (bridge mode)|
|ROUT||Terminal block connector 2 screws – Right Audio Output (Stereo mode) or (-) bridge mode|
|RIN||Terminal block connector 2 screws – Right Audio Input (Stereo) or not used (Bridge)|
|Transformer||12-12V at 25-25V|
|J1,J2,J3,J4,J5||Piece of wire – watch for the high current that will pass through them|
|JB1,JB2,JB3,JB4||Jumper to switch between amplifier modes|
|Printed Circuit Board, Welding, Wires, Box, heatsink, etc.|
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