Zhong Xin Tech-Zhong Xin Tech

For the detection of analog circuit, should focus on the test of DC voltage, AC voltage and DC current, if in the process of testing to master certain skills will greatly improve the efficiency of work. one Dc voltage and Detection techniques 1. Dc voltage detection of amplifier circuit The general amplifier circuit is mostly belong to a class of working state, their characteristics are: whether or not there is a signal, the average current through the transistor is unchanged, the current voltage ＆#118alue reflected to the pin is unchanged, that is, this kind of voltage without signal and the ＆#118alue of the signal is the same, are equal to the voltage ＆#118alue of its dc static operating point. According to the general rule, the UBE of amplified silicon tube is about 0.7V, the UBE of germanium tube is about 0.2V, and UC> UB> UE, so that makes sense. 2. Dc voltage detection of switching circuit Switching circuit is characterized by the work in cut-off - amplification, amplification - saturation cut-off - saturation and other states. Their DC voltage and dc current vary with the presence or absence of signal, that is, with and without signal dc voltage and DC current are different. These circuits are nonlinear, and a DC component is generated when the signal passes through. It is this new DC component that changes the original operating state and enters a new operating state. The static and dynamic voltage difference we measure also reflects this fact, and we can infer whether the signal enters the circuit under test according to the voltage change. two Ac voltage and Detection Techniques Due to < a href = "" https://www.diangon.com/wenku/yiqiyibiao/" "> multimeter < / a > ac voltage shift sensitivity low and internal resistance is low, so communication file output can only be used to test certain have a certain ability to parts of the output voltage. Sinusoidal AC voltage can be directly tested with multimeter AC file. The voltage in the general circuit often contains pulsating components, that is, ac and DC coexist. In this case, it is necessary to cut off dc to test his AC voltage. Specific methods is on the multimeter ac gear series a < a href = "https://www.diangon.com/wenku/rd/dianrong/" "> capacitor < / a >. 3. Dc current detection For some circuits, it is sometimes necessary to test the current of the circuit to determine whether the circuit is working properly. When testing the DC current, it can either disconnect the circuit into the ammeter, or calculate the current ＆#118alue by measuring the relevant voltage resistance in the circuit without cutting off the circuit. Four. We know the proper working state of the circuit, in order to identify whether the circuit is in this state, we must master the method of judging the working state according to the voltage ＆#118alue. < p > 5. 1. Detection of Class A Amplifier circuit Because the < a href = "" https://www.diangon.com/wenku/rd/dianyuan/" "> power < / a > to the collector has a certain resistance, when the collector current change collector voltage will change accordingly. Therefore, after changing the bias state, observe the change of collector voltage can be introduced to the change of current, and further determine whether the transistor has the ability to amplify. This kind of amplifying circuit whether there is a signal, its working point is not changed, so this method is feasible.