Power amplifier 100w vmosfet 1

 One still designing that it uses in the exit transistor of technology V-mosfet. This transistors to us offer a lot of virtues concerning the simple bipolar transistors, as high speeds, thermic stability, low distortion etc. Beyond this circuit use also other useful solutions as use fet as source of current [ Q3 ], trimmer TR1 with which we match the characteristics of differential amplifier of entry Q1-2. Also extensive is the use of sources of current wilson Q7-8 and Q10-11. With trimmer TR2 regulate the bias current of output stage, in the 100 ma. The use of diodes D2 until D5 in combination with the resistances R17-19, they protect the gates of transistors v-fet from exceeds the voltage ? 14V and it creates perforation in very thin layer SiO2, that is used as insulation in the gate. This way of protection is common in all the amplifiers that use these transistors. The total gain of amplifier is 32.6, regulated from the R18, R6 and R8, in the negative feedback. Also is used enough the use of local feedback for stabilisation of operation under all the conditions. Because the transistors v-fet have positive factor of temperature, with result with the increase of temperature is increased also their resistance. This increase has as result the reduction of current that via the transistor, hence also his power. The use of separated supply in the stages of drive and exit, ensures stability and reject of distortion of intermodulation. The initial drawing of is L. Hood and was published by the Wireless Word.

100W bridge amplifier based TDA7294

This 100W bridge amplifier circuit can increase the power level of the audio signal from a source that has a LINE output type.

The heart of thisbridge mode amplifiercircuit is the TDA7294 integrated circuit which is actually a power operational amplifier with a pre-amplifier circuit, temperature control and output short circuit protection. In addition the IC is equipped with separate input Mute (Mute output) and the STBY or Stand-By (Disconnect the power amplifier). Each IC amplifies half-cycle signal input and provides output 50W each.
This 100W bridge amplifier circuit must be powered with /-25V and 4A. Where to stereo equipment requiring current should be 8A. Load (speaker) must be 8 ohms. With these values??, the circuit will deliver 100W with a total distortion of less than 0.1% distortion or 150W with a total of about 10%. Because of this feedback to the speaker configuration to bridge the two terminals (positive and negative), the negative terminal should not be transferred to the ground as in other amplifiers. Doing so will cause a short circuit at the output of the chip and damage it by activating protective if not reversed in time.
For power supply can be use classic transformer or a switching power supply, in the latter case the source must be of good quality and filtered. But if weight is not a problem we recommend using a good old transformer with rectifier and electrolytic and ceramic capacitors.
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TDA7294:
The manufacturer of this IC (SGS-Thompson) should activate the mute function before using Stand-By. This IC generates 1.3 degrees Celsius per watt of power. That is why we have to put on an adequate heat sink to prevent system overheat and cause overtemperature shutdown.
Although the manufacturer claims that this is a built-in 100v / 100w should be remembered that this specification is technically and theoretically. In practice, the integrated circuit can deliver power over a 50w 8 ohm load at a voltage of 50V for starting which consumes about 2 amperes and generates heat.