70W Stereo HI-FI Power Amplifier - High Fidelity using two TDA2050 IC's + PCB

Fig. 1 - PCB 70W Power Amplifier TDA2050

For Portuguese version, click here!

In a previous post here on our website, we made an Amplifier Circuit with IC TDA2050 that delivers 35W RMS of power, it is an amplifier of excellent quality, and you can follow the link below:

HI-FI 32W Audio Amplifier – TDA2050 – Simple PS + PCB

In today's post we'll build a High Fidelity Stereo power Amplifier that provides 70W RMS - with two TDA2050 Integrated Circuits.

The TDA2050 Integrated Circuits

The TDA2050 is a monolithic integrated circuit in a Pentawatt® package, intended for use as a low frequency Class AB amplifier. Typically, it provides 35W RMS output power with 4 Ohm load, THD = 10%, VS = ± 18V, F = 1KHz, and up to 32W RMS with 8 Ohm load, THD = 10%, VS = ± 22V, F = 1KHz.

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The TDA2050 - provides the high current output and very low harmonic distortion, it incorporates a short circuit protection system, an arrangement to automatically limit the dissipated energy, in order to keep the working point of the output transistors within their safe area of ​​operation, that is, a conventional thermal shutdown system.

SHORT-CIRCUIT PROTECTION

The TDA2050 has an original circuit that limits the current of the internal output transistors, the maximum output current is a function of the voltage of the collector-emitter; hence the output transistors work within their safe operating area. 

This function can therefore be considered to be a peak power limitation, rather than a simple current limitation. It reduces the possibility of the device being damaged during an accidental short circuit at the output.

THERMAL SHUTDOWN

The presence of a thermal limiting circuit offers the following advantages:

• An overload at the outlet (even if it is permanent), or an ambient temperature above the limit can be easily supported, as the Tj cannot exceed 150 ° C.
• The heat sink may have a lower safety factor compared to that of a conventional circuit. There is no possibility of damage to the device due to the high junction temperature. If for some reason, the junction temperature increases up to 150 ° C, the thermal shutdown simply reduces the power dissipation in the current consumption.
• The maximum allowed energy dissipation depends on the size of the external heat sink (i.e. thermal resistance); this power is dissipated depending on the ambient temperature for different thermal resistance.

The proposed circuit is a stereo power amplifier, it has two input channels and two output channels, and its schematic diagram is shown in Figure 2 below, and as we can see, it is the same circuit as the 35W amplifier, but it is duplicated making it stereo. 

The circuit is quite simple and can be easily assembled even by people who do not have so much experience in assembling electronic circuits, however, it is necessary to have knowledge of electronics.

Fig. 2 - Schematic Amplifier TDA2050

Component List

• U1, U2 .................................................. TDA2050 Integrated Circuits
• R1, R2, R3, R5, R8, R10, R11, R12 .... 1/4w 22KΩ Resistor
• R4, R9 .................................................. 1/4w 680Ω Resistor
• R6, R7 .................................................. 1/4w 2.2Ω Resistor
• C1, C14 ................................................ 25V 2.2µF Electrolytic
• C2, C15 ................................................ 25V  100µF Electrolytic
• C3, C7, C8, C9 .................................... 35V  1o00µF Electrolytic
• C4, C12 ............................................... 25V 22uF Electrolytic
• C5, C11 ................................................ 100nF polyester
• C6, C10 ................................................ 0.47µF polyester
• RP1, RP2 ............................................. 47KΩ Potentiometer
• P1, P3 …......….........................…........ Screw Terminal Block: 3-Pin, 5 mm
• P2 …............…..............................…... Screw Terminal Block: 2-Pin, 5 mm
• Miscellaneous: printed circuit board, heat sink, box, tin, wires, etc.

Printed Circuit Board

The layout of the Printed Circuit Board is shown above in Figure 1, and we have all the necessary files for you to be able to print your PCI, with the GERBER files, PDF Layout, JPG, all with a direct link for you to download and assemble yours.

Downloadable files

Files: Gerber, Layout in PDF, PNG, for download. Direct link: Click Here

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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