With the development of the times and the continuous advancement of technology, high-quality audio-visual equipment such as large-screen color TV sets, advanced CD/MD combo systems, and DVD players have been widely used in recent years. In the past, there were recorders, video recorders and VCD players at home. I am afraid that no one is interested in them anymore. It has been learned that many people have not operated radio cassette recorders and video recorders for many years, and VCDs have also been replaced by new ones. Some people even feel that it is a pity that they simply dispose of these household appliances as second-hand goods or even waste products.
Really, although these outdated home appliances are indeed outdated, if we can use the little radio knowledge we have, or have a friend with radio expertise to help them, and transform them, we can turn waste into treasure and make the best use of our products. . Let's talk about some of the author's practices.
Split dual card recorder
The 1980s was the era of split-type dual-card recorders. Many homes still have these large-scale home appliances. The author once had a large-sized jewel-licensing split-card dual-card recorder at home, and when I bought it home, I felt that the sound quality was really good and I had been using it for many years. Until after the purchase of a high-end stereo system, the dual-card recorder was put aside, feeling "disappointing and useless." So after a lot of surgery, it was transformed into a small set of active speakers. The specific practices of the transformation are as follows:
First, remove the left and right speakers of the Jeweler's tape recorder from the body. The original amplifier of the tape recorder uses a low-power integrated circuit TDA2004. Its power is only 5W×2, and its reserve power is too small. It is decided to abandon it. Then a mail order for a LM1876 amplifier board with a power of 20 W×2 and a 50-watt power transformer cost less than 100 yuan. Then open the rear cover of a speaker, replace the small pieces of supporting wood inside with a slightly larger board, and then fix the LM1876 power amplifier board and the 50W power transformer to the board, and pull apart a certain distance between the two. A thin iron sheet is shielded from the power transformer to prevent the leakage magnetic field from interfering with the power amplifier circuit. Then fix a 10K×2 volume potentiometer, a mono 3.5mm socket (for outputting another channel signal) to the speaker back cover, and finally make a simple connection to the power cord and audio input cable. Deal, the entire conversion work will be done.
This small active speaker can be used for multimedia computers as well as home theater surround channel speakers, which is very convenient and practical.
VCR tape recorder
The VCD, DVD's pandemic has turned the video recorder into a superfluous home appliance. In fact, many video recorders have reached a very good level of quality and functionality. Many models have 99 sets of programs for pre-programmed storage, cable TV supplemental channel reception, "Namto" demodulation, and Hi-Fi stereo recording. The functions still have use value so far, but people have not fully utilized them.
At present, cable television is widely used throughout the country. Most cities can already provide 30 to 40 TV programs, and it may soon increase to 60 or 70 sets or more. However, some old TVs do not have the function of receiving supplementary channels for cable television, but only pre-set the storage of twenty or thirty channels. This obviously cannot meet current needs. Although these problems can be solved by replacing the cable tuner and increasing the memory, it is more troublesome. If you plug the video recorder into the middle of the TV cable and the TV set, let the video recorder receive and demodulate the audio and video signals, and then connect to the TV through the AV terminal, you can solve the problem of multi-program reception. In Beijing and Guangzhou, the issue of receiving "Li-Yin" televised programs that have already been broadcast by TV stations can also be solved in this way.
In addition, Hi-Fi recorder itself is a high-quality analog recorder. Due to the use of rotary heads, frequency modulation, dynamic compression, and deep multiplexing to record two-channel stereo signals, the Hi-Fi recorder's acoustic performance is much better than that of ordinary tape recorders, with a wide frequency response (20Hz-20kHz) and large dynamics ( 90dB). The advantages of small distortion (0.005%) can meet the high fidelity requirements. The author and some of the friends around me still like to use it to copy CD music. Whether you are an audiophile or an ordinary user, if you take advantage of this feature of Hi-Fi recorders, you no longer have to pay high prices to buy an MD or watch a CD-R/RW recorder.
VCD player
With the increasing popularity of DVDs, the previously used VCDs have become less and less efficient. Many people think that since the purchase of a DVD, VCD naturally has no use value.
However, we must not forget that VCDs are compatible for playing CDs. However, the sound quality of CDs played by VCDs is poor (DVD is also the case). The main reasons are: 1. CD signals go through MPEG-l decompression boards, and audio and interference are heavy. 2. For cost reasons, VCDs are generally Use a low-grade audio DAC decoding circuit. Therefore, only when the VCD is modified can it be used to play CD recordings.
In fact, if you want VCD to have better sound quality performance, it is not difficult. First of all, it has a unique advantage in the movement. Many domestic VCDs use high-performance Philips digital servo movements. This type of movement reads the accuracy and correction of the optical disc signal. The higher error capability is far better than the Sony analog servo movements used in general CD players. The head digital servo circuit can automatically adjust the state of the movement system, so that all parameters are maintained at the set optimal value, so as to ensure the stability of the work. Therefore, the machine using a digital movement should be much better than the sound quality of an analog movement. Obviously, the focus of the transformation of VCD is to solve the problem of the CD signal processing circuit, mainly to increase a high-quality audio DAC decoder board.
The author has a golden genuine S-VCD, which uses the Philips digital servo movement. Due to the poor sound quality of the CD played, he purchased an audio DAC decoder board (the main integrated circuit is PCM1716 + OP275) by mail order for more than two hundred yuan, and processed it into a dual-circuit dual-output CD/VCD disc. machine. In the reconstruction, only the decoder board must be fixed in the machine first (the space inside the machine is very affluent), and the connection work is done. The machine has two original audio output terminals, one of which is changed to a CD straight output terminal. After repeated trials, the sound quality was indeed improved. No matter if the frequency response or the dynamic performance was excellent, the music effect was much better than the other Sanyo CD player used by the author for many years.
If you now have home appliances that you are trying to phase out, try out the method I described above. Although not much money is spent, but the results are significant and enjoyable.
BNF HARDWARE CO., LTD , https://www.bnfhandles.com