Keywords: FM stereo radio production
FM three-dimensional radio
Author: Lu Guowu
The author exposed to the red light electronic tube radio in 1988, it was only 7 years old. From then, it was rampant to become "radio fan." In recent years, the radios are not less than 30, and the radius radio has six, Sony, Mitsubishi and other six, the combined audio tuner has nine, and the equipment is good, the equipment is good, and it is not possible to carry it with you. Use the leisure time to design a three-dimensional cocovered radio to make yourself, the effect is good, and this is to communicate with the majority of enthusiasts.
First, the structure block diagram is shown in Figure 1. The author uses an Alpay car electrical tone integration high frequency head, which is in size, which is prone to a pocket machine. To meet its working conditions, it is specifically equipped with a DC-DC converter, 9V regulator, and the like.
Second, the component selection integrated high frequency head has high performance, fully enclosed structure, its model is the MB4A605F type.
The transformation is made of MC34063 chip because it has strong load capacity.
The stereo power discharge Ic selects a LAG668FT chip that has a DC volume control function and the peripheral circuit is simple. The antenna amplifier in Figure 2 consists of a V1 tube or the like.
Third, in the introduction of the working principle, in Fig. 2, the signal received by the antenna is enlarged by V1 after passing through the v-pass filter, and the C2 is coupled into the Albai integrated AM / FM high frequency head.
The high frequency head has a total of 34 pins, many functions, but as a pocket machine, everything is from simple, this is the characteristics of this machine. After the signal processing, the signal is output, the L, R stereo signal is output, and the power amplification of the LAG668FT is output. VR3 is a DC volume control potentiometer that can be regulated.
The DC is converted to the MC34063 converted output + 12V voltage, the 12V voltage is output from the 7809 regulated output + 9V voltage, + 9V voltage is divided into three roads: all the way to high frequency header power supply voltage; all the way supplied to VRL as high frequency head FM Put the gain adjustment, perform the medium-release gain adjustment to make the high frequency head working at the optimal state; all the way to supply VR2 as a tuning voltage after the DL regulator, by adjusting VR2 to reach the set table purpose.
Antenna amplification and power amplification direct use of power.
Fourth, debug this unit The only thing to debug is the FM medium amplification gain debugger, method: 1. Receive a strong signal station, adjust the VRL to make the radio sound, the sound quality, under the premise of no signal blocking, both, both each other It is best accurate in sound quality. 2. Receive a weak signal station, then fine tune the VRL to minimize the background of the radio. When debugging, repeat several times, if you are fixed, if you use the quality headset to listen, the result is the most obvious and more than half of the skill.
5. The casing housing is preferably used in the cosmetic case used by the ladies, and the size is about 140mmx70mmx20mm.
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