#2n3055 transistor jvc receiver free

This method causes a standing bias current to be flowing during the whole waveform cycle, and even when no signal is being amplified. The output power they produce is theoretically 50%, but practically only about 25 to 30%, compared with the DC power they consume from the power supply.Р”В¬lass A power amplifiers use the biasing method illustrated in Fig. Class A design produces good linear amplifiers, but are wasteful of power.

#2n3055 transistor jvc receiver free

The purpose of class A bias is to make the amplifier relatively free from distortion by keeping the signal waveform out of the region between 0V and about 0.6V where the transistorРІР‚в„ўs input characteristic is non linear. In either of these states the transistor is dissipating little or no power. Classes D to H are used in switch mode amplifiers where power is saved by having the output transistors switched rapidly between fully on and fully off. The classes A, B, AB and C refer to the way the amplifiers are biased, although class C is mainly used in oscillator circuits. Although Class A may be used for power output stages (usually low to medium power), it is less used for higher power output stages, as more efficient classes of amplifier such as Classes B, AB or even classes D, E, F, G and H are available. Since the speaker is a reactive load (especially at high audio frequencies), the reactance is reduced via the 100nf, 10РћВ© resistor РІР‚вЂњhelps prevent oscillation.The Class A Common Emitter Amplifier described in Amplifier Module 1, Module 2 and Module 3 has some excellent properties that make it useful for many amplification tasks, however its use as a power amplifier is limited by its poor efficiency. The 1500uf coupling cap keeps the DC portion of the output bus voltage off the speaker. In this way, the anode of the capacitor actually transcends the bus voltage when the output bus goes positive so that the BC286 has lots of base drive and can easily turn on fully. The 100-200uf capacitor is a РІР‚СљbootstrapРІР‚Сњ capacitor that couples the output bus to the 1-3K pullup resistor. The lower 2N3055 is connected to the BC287 in a composite connection that essentially turns the BC287 into a high current gain PNP transistor. The complementary transistors are both connected in the common collector configuration (emitter followers) so they have essentially unity voltage gain.Р”В¬oupled to the BC286 is the 2N3055 in a Darlington configuration. If the bases of these two transistors were tied together, it would be a zero bias class B, but the bias regulator develops just enough voltage to put the complementary transistors just on the edge of conduction. The BC107 is the bias regulator that develops approx 3 junction drops (1.95V) to properly drive the complementary transistors (top BC286 and the BC287). C1 and the resistor above it also provide frequency comp by reducing the AC feed back to the input stage. It is the high voltage gain element and requires a frequency compensation cap (C2) to prevent oscillation. The top left capacitor and resistor are noise decoupling for the bias source for the input transistor to keep it from amplifying the power supply noise and ripple.Р”Р„ signal is picked off the collector resistor to drive the base of the lower BD286.

With feedback as such, it has essentially unity AC and DC gain.

It also regulates the DC operating point of the output bus. The PNP input stage is configured as a common emitter amplifier with lots of current feedback through the emitter resistor that is tied to the output bus.