Microphone, also known as microphone, is a kind of electro-acoustic equipment, which belongs to microphone. It is a transducer that converts sound to electricity. The voltage is generated on the electro-acoustic element through sound waves, and then it is converted into electric energy. Used in a variety of loudspeaker equipment. There are many types of microphones and simple circuits. After the appearance of the microphone, a microphone lifter appeared. This lifter is mainly used to adjust the height of the microphone. For example, we usually host meetings and often see the microphone holder at the party.

       Analyzing the microphone circuit mainly grasps two points: (1) The signal transmission loop analysis is relatively simple, and various microphone input jack circuits are analyzed. (2) Microphone signal amplifier analysis. The microphone amplifier is a small-signal low-noise audio amplifier. It is not difficult to analyze the microphone level control circuit.

       Microphones are usually classified according to the way they convert energy. Here we still divide the microphones into dynamic microphones and condenser microphones according to the most common classification of microphones in the studio. However, the microphone lifter does not need to distinguish different lifters according to the classification of the microphone.

       Dynamic microphone: A microphone that generates electrical signals from a conductor moving in a magnetic field. It is the diaphragm that drives the coil to vibrate, so that the coil in the magnetic field induces a voltage. Features: firm structure, stable performance, durable, low price; good frequency characteristics, flat amplitude-frequency characteristic curve in the frequency range of 50-15000Hz; good directivity; no DC working voltage, easy to use, low noise.

       Condenser microphone: The diaphragm of this type of microphone is an electrode of the capacitor. When the diaphragm vibrates, the distance between the diaphragm and the fixed rear plate changes, resulting in a variable capacitance. This variable capacitance and the microphone itself The pre-amplifier that comes with it produces the signal voltage together. Features: Good frequency characteristics, flat amplitude-frequency characteristic curve in the audio range, which is better than dynamic microphones; non-directional; high sensitivity, low noise, soft tone; relatively large output signal level, low distortion, and transient response The performance is good, which is an advantage that a dynamic microphone cannot achieve; the working characteristics are not stable enough, the low-frequency sensitivity decreases with the increase of the use time, the life is relatively short, and the DC power supply is needed during work, which makes it inconvenient to use.

       With the development of society, the microphone lifter has also been reformed, and some microphones have also appeared wireless microphones. The microphone is tuned in the 88-108MHz FM band, with a transmission distance of about 30 meters, and can be received by any FM radio, and the received sound is clear and pleasant, without clutter interference, and has no effect on local FM radio stations.