Does a transistor amplifier produce negative voltage?
No, the output could never go negative in this circuit, it is relatively simple to understand why.
The best mental model of how transistors work that I've seen comes from &quot;The Art of Electronics&quot;. Imagine a little person sitting inside the transistor, there is a diode connected from the base to the emitter with an ammeter hooked to it, and there is a variable resistor connected between the emitter and the collector which the little man controls. Depending on what value he sees on the ammeter he will adjust the variable resistor accordingly (the exact relationship isn't important for this question).
As such if you imagine the transistor in this circuit as basically a diode and a variable resistor you can quickly see that no matter what value the resistor could possibly be at the voltage presented could never go outside of the voltage of the rails themselves. You have a positive rail and 0V rail. As such you know it is guaranteed your voltage can never go negative.
Even if we assume the base could go negative somehow that still wouldn't cause the output to go negative. If the base goes negative than the diode becomes reverse biased and will not conduct. As such the transistor wont engage and the virtual variable resistor between collector and emitter will remain high. so your output voltage would still be positive.