Non-exam preparation materials, but I like to record.
1.14
Introduction
Electronic technology consists of two parts: analog electronic technology and digital electronic technology. The difference between the two lies in the different signals processed. The signal processed by the former is continuously changing in time or value, such as temperature and speed, which are called analog signals, and the corresponding circuits are called analog circuits. Both voltage amplifiers and power amplifiers are the main components of analog circuits. The signals processed by digital electronic technology are discrete. For example, an automatic counting production line sends out a pulse every time a product comes (for example, the light source of the photoelectric element is blocked). This type of signal is called a digital signal, and the corresponding circuit is called a digital circuit. . The photoelectric signal becomes a digital signal after being reshaped. Counters, decoders, and LED digital tubes are the main components of digital circuits. (Continuous pulse transmission)
Chapter 14 Semiconductor Devices
Semiconductor applications: thermistors, photoresistors, semiconductor devices.
Diodes and bipolar transistors are the most commonly used semiconductor devices.
Intrinsic semiconductors are semiconductors with complete purity and complete crystal lattice (with crystal structure).
There are both electron conduction and hole conduction in semiconductors. Both free electrons and holes are carriers.
Intrinsic semiconductors are doped with a small amount of impurities (a certain element) to form impurity semiconductors. Impurity semiconductors are divided into two categories: electronic semiconductors (N type, doped with phosphorus or other pentavalent elements), hole semiconductors (P type, doped with boron or other trivalent elements).
In general, atoms are electrically neutral. No matter it is N-type or P-type, the whole crystal is still uncharged.
Expand knowledge:
1. The thermocouple is a commonly used temperature measuring element in temperature measuring instruments. It directly measures the temperature and converts the temperature signal into a thermoelectromotive force signal, which is converted into the temperature value of the measured medium through an electrical instrument (secondary instrument).
2. Servo mechanism is an automatic control system that enables the output controlled quantity of the object's position, orientation, state, etc. to follow any changes in the input target (or given value).
3. Silicon, germanium, selenium, and most metal oxides and sulfides are semiconductors.