Dongguan learning machine to join, select the school and the first national brand to buy a "learning and the first" National Machine beneficiary families, they say: Shenzhen Small-kun (7 year old boy) mother: Great! To read through Sinology become very, very loose, I had spent a lot of money to buy a lot of sets of discs, there are no set is complete, wear flowers, lost, and stuck out of play. This Sinology machine, and everything the whole, I finally freed from the CD inside it. Fujian vast (three year old boy) father: the child's mother is doing Early Learning Center, we have been the classic sense, although the child hears finished "Rules", "Three Character Classic", but the machine still surprise us Sinology content too rich! Listen now round the child, nor even watched television. Now, I have to not go to school and the first Sinology machine Fujian agent, goods sent back, ten days for the sale of more than one hundred units, have never done such a good promotion products. Xiangtan - Zheng: I every day in the classroom, playing 20 minutes at noon Classic, a semester later, our class children, in memory, reading and writing have improved to varying degrees, the area where the speech contest, a prize, second prize are the kids in our class. This is a pleasant surprise, we did not think Sinology machine class kids more standard pronunciation, speech more appealing up! Learning and First Technology Co., Ltd. mainly produces electronic products, audio materials, communications equipment, and other educational products. Domestic and international sales. Over the years our products with its powerful, reliable quality, stable performance is known, the majority of users and dealers who praise. School and the first technology to provide customers with reliable products and fast scientific quality service. Let early education, Chinese culture and other fields of science and technology possible. The following article for information purposes only H-bridge motor drive circuit I first branch switches and branch with motor coordination to form as shown in the voice repeater chip voice recording technology in the application of H-bridge motor control and drive circuits. Since this circuit structure resembles the shape of the letter H in English, it was this name. The basic principle is as follows H-bridge when the switch SW and SW is closed, the switch SW and SW is turned off, the current flows in the direction shown by the arrow in Fig species through the motor, the motor axis of rotation, assuming it clockwise. When the switch SW and SW is closed, the switch SW and SW is turned off, the current flowing to the motor from the other direction, the motor rotates in a direction axially opposite, namely counter-clockwise, as shown. Figure Figure forward reverse voice repeater chip voice recording technology in the application diagram H-bridge motor drive circuit, consisting of a transistor H-bridge driver circuit switches the image above will now be replaced by a transistor, constitutes transistor shown in Figure H-bridge circuit. For easy control of the circuit, used in the circuit of transistors of different polarity, i.e. a PNP type transistor and an NPN type transistor. The upper figure to provide a current drive, using a PNP type transistor, needs to absorb a lower drive current, using an NPN type transistor. R transistor's base current limiting resistor, A, and B a control signal input terminal. Appropriate control signal on and off a transistor H-bridge is very important H-bridge transistor is in the positive power and ground between a channel. When terminal A is low, B-side is high, the transistor conduction VT and VT, VT and VT off, the current through transistor VT pin left motor and right pins, VT transistor flows, the motor Axis forward. And when the A side is high end is low, transistor, B voice repeater chip voice recording technology in the application of VT and VT conduction, VT and VT cut-off, the current through the transistor VT pin motor Right, Left pin transistor VT flow, with the last opposite direction, the electric Dongguan learning machine to join, select the school and the first national brand