The active speaker amplifier I recommend to everyone uses two integrated circuit chips, namely LM 4766 and NE 5532. Among them, LM4766 is an audio power amplifier specially designed for digital circuits by American Semiconductor Company. It can produce 30W & TImes; 2 sinusoidal output power on an 8Ω load when the positive and negative 30V power is supplied. advantage.
The pre-amplification part adopts NE5532 as a 10 times amplifying circuit. The coupling capacitor selects the German WIM polypropylene supplement capacitor. The large-capacity filter capacitor selects the Japanese ELNA electrolytic capacitor. The resistance uses five-ring metal film resistors. The power amplifier circuit is shown below.
The power supply part uses toroidal transformer 100W double 18V. Powering NE5532 is done by 7812 and 7912. The rectifier uses 3A full bridge. The {6} and {11} pins of the LM4766 are the left and right channel Mute control pins, which can be controlled together or separately. (This connection method is controlled together by me. If you want to control them separately, you need to change the { 6} feet and {11} feet are connected to {4} feet of LM 4766 respectively). The treble uses the silver flute YDQG5-2, the maximum power is 30W, and the bass selects the silver flute YD178-P, the maximum power is 60W.
After connecting all the circuits and devices, the sound of the audition is soft and beautiful, full and flexible, especially the shocking effect displayed when playing 3D games is really indescribable. 
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Magnetic Starter is mainly applied to circuit of AC 50 or 60Hz,voltage up to 550V for far distance making and breaking circuit and frequent start and control motor. It has the features of small volume, light, weight, low power consumption, high efficiency, safe and reliable perfomance etc.
The types of Magnetic Starters are as following:
LC1-D Magnetic Starter
NEW Type Magnetic Starter
BLS-MB Magnetic Starter
Star-Delta Starter
Magnetic Starters
Magnetic Starter,Magnetic Motor Starter,3 Phase Motor Starter,3 Phase Magnetic Starter
Ningbo Bond Industrial Electric Co., Ltd. , https://www.bondelectro.com