Audio amplifiers are in use for last several decades. Before the invention of transistors, thermionic tubes were used in amplifiers. Later when transistor had invented it changes the entire world of amplifiers. Transistor amplifiers were commonly used everywhere. Transistor amplifiers were small and they were consuming much less power compared to tube amplifiers. Two types of transistors were very common. In older days Germanum transistors were common. But latter Silicon transistors replaces those Germanum transistors due to special characteristics offered by silicon transistors over germanum transistors.
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| OLD days Germanium transistors amplifier |
Latter with the advancement in technology, IC was invented and the amplifier circuit was one the most ICs had been made of. IC amplifiers offer much more advantages over transistor amplifiers. Low price, simple design, very few external components, much more stability and ease of repair are a few benefits IC amplifiers are providing over transistor amplifiers. Now a days almost in all designs IC amplifiers are used.
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| STK IC amplifier board |
Here a 100W TDA7294 IC amplifier is introduced. This amplifier has great loud sound and its price is very low. Under $1 this chip could be obtained and very few external components are required to construct or build the whole amplifier circuit. Anybody with little electronics experience can build or make this circuit. They circuit stability is great. As this is very high power amplifier, it's a must to mount the IC on an appropriate heat sink to prevent is from burning due to heating up. The rest of the circuit is straight forward.
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| TDA7294 amplifier circuit schematic |
The power supply is +37V and -37V DC stable is needed for this circuit to operate at maximum performance. High power amplifiers have normally high voltage power supply needs as power is a factor of voltage. So a linear transformer type power supply could do well. The power transformer should be a center tape type with appropriate wattage rating to run both stereo amplifiers without any voltage drop overheating problem. Bridge rectifier should also be of high current ability and should be mounted on a heat sink of radiate it heat in the atmosphere. The filter capacitors should also be of high capacity. 4700UF 50V value capacitor from any good manufacture would do the best.
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| TDA7294 amplifier dual power supply circuit |
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