In lab, we are constructing a power amplifier. We built it first in Multi Sim, ran a transient analysis (picture below), built it on a protoboard and then ran it through an oscilloscope to make sure it ran as intended.
We set it up exactly as pictured in our schematic, we checked it a million times. For some reason, when we increase the amplitude from the function generator passed a certain voltage, the output of the DC power supply starts to decrease and seems to stop at around 6 volts. The problem with this is that it is now biasing it at 3 volts, instead of 6, at the base. And now is causing it to distort.
Does anybody have any idea as to why the DC Power Supply output would decrease when we increase the function generator amplitude?
Thank you very much.
Best Answer
It's called "source impedance". Your power supply is simply not capable of supplying the current that you're asking for. Perhaps it has a "current limit" knob that's set too low.
6V (peak) into 8Ω should require a peak current of 750 mA.