Cheap and beautiful bedside HI-FI-03

This system consists of a CD player, power amplifier, speakers, power supply , and headphones.
    The CD player adopts the 4-speed CD-ROM launched by Misumi specifically for mainland China in 1997. The panel has accelerator and cartridge entry and exit keys, and has
strong disk reading capabilities. The PHILIPS 731 CD player at home cannot play the turntable normally, but it can be played here smoothly. It is cheap and
has good treble resolution, but it is not powerful enough. It feels immovable when worn directly with headphones, but it is an absolutely value-for-money product
. Most Hitachi products at the same price are parallel imports and cannot play CDs directly.
    The self-made power amplifiers are TL082 and TDA15 21. The circuits are shown in Figure 5-74 and Figure 5-75. 6 The power supply voltage of the machine should not
be higher than dual 14V, but the power should not be lower than 20W. Use dual 12V E-type transformers. 々The resistors are all 1/4W5 ring gold film 6
capacitors made of domestic monolith and polyester. The input of TDA1521 uses SANYO's 47uF/6, 3V organic solid capacitor t
560VF/35v electrolytic, which is an ordinary product of ELNA. There are only a few imported capacitors here. It is related to the sound quality and cannot be sloppy, but
the price relatively high. Review the power amplifier A 48×6 cooling fan is used for heat dissipation, and there is basically no interference noise.
    The speaker is made of two Nanjing YD-110-8SXA speakers mounted on the plastic shell of a car speaker
. Its frequency response data is from mid to 10000Hz. The low frequency is not deep but the response is fast and accurate, and the vocals are good. In fact, the fundamental tone of musical instruments is not much higher than 8000Hz
. I tried playing Tchaikovsky's "Piano Canto No. 1" and "1 8 1 2", and I felt that the steel sound was more accurate in most cases.
The brass instruments can make you feel radiant and brilliant, and the sound of gunfire can't be said to be submerged. , the sound pressure level is not large. But it is clear that the Q connection uses
30 strand "gold and silver" lines of 1 yuan/meter . This speaker has
the largest magnet among the 4-inch speakers, which is similar to some 6.5-inch magnets
. It is also shielded and can be used as a center or main channel midrange
speaker.
    The power supply adopts "UPS". A 14V/2A switching
power supply generates all voltages. When there is a power outage (lights out),
the battery is used for power supply. The circuit is shown in Figure 5-76. The battery
capacity should not be less than 4Ah, and it can also drive a battery at night.
An electric fan blows the air, a small light bulb lights up and I read a book.
    Students who like to listen to headphones can make their own headphone amplifier. It is best to use two pieces of AD847 to make your own. For headphones, we recommend S()NY's
741 earphones and PHILIPS' SBC100 headphones. You can refer to them based on your economic strength. The characteristic is balanced performance. Good value for money÷