Basic transistor amplifier circuit has a total shot amplifying circuit, amplifying circuit, amplifying circuit and a total set which were shot amplifying circuit is one of the most widely used method, the image below for the triode amplifying circuit principle, the left end of the input and output right, emitter (e) is the public end of the input and output, so called total shot amplifying circuit,




Today's video is want to build above the transistor amplifier circuit, by the help of the LOTO oscilloscope and signal generator module and observe the whole circuit of input and output signal waveform, our physical circuit diagram with 2 n3904 triode as the core, the Rb=300 k, Rc=1 k; After many experiments, we take the resistance value can let the triode is as far as possible put regional and far from cutoff region and the saturated zone, physical diagram of the circuit as shown in the figure below,




Video of the specific process is as follows:

https://www.bilibili.com/video/BV1fi4y1t79b/


After fitting of our circuit, open the PC software of oscilloscope intuitively clearly see that the output signal is compared with the input signal is amplified many times, at the same time because the total shot circuit characteristic of amplifier circuit, amplifying the output signal is input signal reverse amplifier, by comparing the figure of waveform phase can be intuitive to see the output signal and the input signal is a reverse amplification,






Thinking: why the triode was shot amplifying circuit, making the output is a reverse amplification?

Base input voltage increases, the base current increases, the collector current is also increasing, collector current collector on the resistance voltage is higher, the collector output voltage minus the collector=supply voltage resistance voltage, so the collector output voltage drop, which is the base input voltage increases, the collector output voltage drop, i.e., reverse,