First, the connection between electricity and the water is invisible, can't touch (low voltage), to master its characteristics, the introduction of the information and its own imagination, it is really difficult to understand. Water is very familiar, it can be seen and still in which people are inseparable from water every day, so it is very understandable. If we get electrical metaphor, the current, voltage, resistance, alternating current, direct current, leakage, ripple, circuit, and capacitors are easily understood. After the electricity is applied to water, the current is equivalent to the water flow, the voltage is equivalent to the water pressure, the resistance is equivalent to the obstacle in the water flow, the leakage is equivalent to leaking, the ripple is equivalent to water waves, the circuit is equivalent to the water path, the capacitor is equivalent to water. Container. In the amplified circuit, you must first get the appropriate DC operating voltage, it can work properly. For example, the magnifying tube is an NPN-type three-pole, and its DC current flows from the base of the triode to the emitter, and the collecting electrode current is also flowed to the emitter, and the direction of the DC current is fixed, it is equivalent to the water flow of the big river; however, The triode amplified AC signal changes regularly. Beginners are difficult to understand, because DC current (voltage) is much greater than AC signal current (voltage), how can it go back to DC? Further, it is also contradictory with the triode conduction current (voltage) direction. It is not difficult to understand, see the DC current here as the water flow in the river; and see the exchange signal in the large river, although the water flow is constant, but the motorcycle can be sailed, or the water sailing can also be sailed. . If there is no water, the ship cannot be lineged (the triode has no static working current, there is no big effect). Second, the TV signal circulation is connected to the transportation and broadcast TV signal in the transmitting end. To modulate the video and audio signal into a high frequency signal, emit out by the antenna (video and audio signal frequency television signals into fixed intermediate frequency signals (38MHz) After the enlargement, after the processing, restore (demodulation) into the video and audio signal of the transmitted end, and then send it to the respective related circuits. We use the audio and video signals as two neighbors, they go far from the local business trip together (Not suitable for walking), apply for a check-in (airplane), which is called high-frequency signal. The plane takes off is launch. After the plane is flying, it is received, and they will take a taxi from the destination (airport) to become an intermediate frequency signal. At the end of the route, the passengers travel is to get a demodulation. Last walking from your end, the amplifier and car contact the amplifier are an electronic device that enlarges weak signals. Beginners are not easy to understand. It is neither like Magnifying the mirror, nor does it meet the conservation of energy. The car throttle everyone is clear. It is the speed of the car. Under the same gear, the larger the throttle is, the faster the speed is slow. The car throt is passed through the driver. The foot is controlled, the feet force size determines that the speed is slow, then we can think that the car put the driver's foot, the car is the amplifier, the force is the weak signal, the speed is the signal. The essence is Implementing energy control, that is, with small energy to control large energy, and uncomfortable with energy conservation. III contact inductance and love is always hindering current change of the flowing coil, that is, inductance occurs both The current of the coil is large, and it also hinders the current of the flow through the coil. The inductance is metaphor into a girl, the current is more than love; the guy is chasing the girl, although the girl is agreed, but keep cautious, they have to pass the process, love progress cannot be Excessive, girl (inductance) hinders to love progression (current change).
