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Circuit's Blog :
Return to Blog

Class A Power Amplifier with 40W Output

Posted Jan 17, 2012 at
3:34 pm

The circuit was designed to produce an audio power amplifier that operates in
the range of Class A type while providing a power output of 40 Watts.

Class A – refers to an output stage where the bias current is greater than
the maximum output current thus, all output transistors are always conducting
current due to its linearity and low distortion

MPSL01 – an NPN amplifier designed for high
voltage, general purpose amplifiers and gas discharge display driving,
enclosed in a TO-92 package

PMD16K100 – a 3-terminal monolithic epitaxial base structures NPN
Darlington power transistor with built-in base to emitter shunt resistors and
CVD glass passivated to increase reliability and
provide reduced high-temperature reverse leakage current while the other
features include low thermal resistance for more useable power and lower
operating temperatures, hermetically sealed, and guaranteed for operating
junction temperature range of 0º – 200ºC

2N6284 – a complementary silicon epitaxial-base NPN power transistor in monolithic Darlington
configuration mounted in Jedec TO-3 metal case intended for general purpose
amplifier and low frequency linear and switching industrial applications since
it has integrated anti-parallel collector-emitter diode

In normal operation of the circuit, the final stage of the power amplifier is
producing 40 W for every 8 Ohms of load. A very high current is allowed to flow
since the power transistors are always in the ON state. Because of this, the
consumption of power is also very which would always result to a very high
temperature being emitted. On the other hand, this is very ideal for the
transistors to work well because of much better characteristics of audio that
they can achieve due to low distortion.

The final amplifier can be designed in a simple manner but would require an
experience in this field of assembly. The circuit is utilizing Darlington
transistors as the main component of the circuit design. It is placed at the
output stage to provide a much higher current gain because the current amplified
by the first transistor is further amplified by the second transistor. The two
transistors are connected in such a way that the emitter of the first transistor
is connected to the base of the second one. They come in transistor-like
integrated circuit packages and produced an American company known as Lambda.
The Darlington transistors can also be replaced with components that would
provide the same desired output.

The whole circuit should be enclosed in a casing that is wide enough to
provide sufficient space including a large heatsink and a strong power supply.
The use of Class A approach is for more linear and less complex design of the
circuit.

The design of the 40W power amplifier is typically applied for FM broadcast
including broadband VHF or RF range. In other
applications, this power amplifier increases the power of loudspeakers with high
resistance and low voltage. Similarly, it can be used for high-end stereo TVs,
compact stereo, surround sound amplifiers, component stereo, and self-powered
speakers.

Source:users.otenet.gr/~athsam/power_amplifier_40w_class_a.htm

Tags: 40 W Class A Power
Amplifier

Comments on this post:

By jay manalo
0Score:

7 years ago:  Power amplifiers are really an essential
part of an audio system. I am going to build this to upgrade my old stereo and
see if I can get more clear signals. Thanks

Login or Register to post comments.

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