How to combine MP3 and tape recorder to play old tape recorder modification
With the increasing popularity of high-fidelity player MP3, the price has dropped again and again, taking advantage of its advantages and existing The appropriate “combination” of the tape recorder makes the “audio” regain its “youth”.
1. Connection of equipment
Generally, radio cassette recorders have line input jacks (marked with “LINE.IN” symbol), which can be found in electronic equipment stores According to the aperture of the MP3 headphone jack and the line input jack of the tape recorder, buy an audio cable with corresponding diameter plugs at both ends, insert one end into the headphone jack, and insert the other end into the line output jack of the tape recorder, some large tape recorder line input jacks It is a double lotus seat, buy the corresponding audio cable and insert it at will according to the input hole L\R. If you can’t buy such an audio cable, you can make your own.
After connecting the audio cable, put the recorder signal input selector switch to the line input LINE, the IN position can select the track from the MP3 to play.
If the tape recorder does not have a line input jack, you can use the following method to connect:
The school tape recorder generally has the FM radio function. FM frequency band tuning to listen to the sound of MP3 playback, this method is most suitable for teaching use. If the recorder does not have FM radio function, you can open the back cover of the recorder, find the volume switch, and weld the audio cables to the two ends of the potentiometer respectively, and connect them to MP3 after they are drawn out.
MP3 can not only play songs, radio exercises, eye exercises and other teaching songs, but also can play text reading, and you can quickly select the content you want to play according to the display of subtitles.
Second, the method of recording audio sources
The above modified playback equipment must have sufficient audio sources. Every school has many teaching CDs and tapes. The contents of a disc or tape can be imported into a computer. Save in mp3 or wav format as a teaching audio source.
1. Record with CD
Put the CD with the teaching content into the CD-ROM drive of the computer, and use the audio solution or other conversion software to convert the relevant content. Convert it to mp3 or wav format, edit the appropriate name and save it in the computer hard drive. After the audition is correct, you can copy it to MP3 through the data cable.
2. Record with tape
Use the audio cable with the corresponding plug to effectively connect the line output of the recorder with the line input of the computer, insert the tape to play , use the program “recorder” function that comes with the computer system to convert the content of the tape into mp3 or wav format that can be played in MP3 and store it in the computer. The “Voice Recorder” function of the computer can only record one segment per minute, which is more complicated to operate. Recording software such as WAVECN1.90 can be used for recording. This kind of software can splicing and synthesizing the recording content, and it is very convenient to edit audio files.
Precautions for the production and use of medium-wave magnetic antenna for audio machines
The magnetic antenna is a magnetic rod wound with two sets of coils that are not connected to each other , the medium wave magnetic antenna is shown in the figure above. Its function is to receive electromagnetic waves in space. The magnetic antenna has good directivity, so that when the radio is rotated in a certain direction, the sound is the loudest, and the noise is reduced. In the process of assembling a transistor radio, a magnetic antenna can be made.
1. The Q value of the magnetic antenna is related to the material of the magnetic rod and the frequency of use. Manganese-zinc ferrite magnets are used to receive medium-wave signals; nickel-zinc ferrite magnets are used to receive short-wave signals. For magnets with the same diameter or cross-section, the longest length should be preferred to improve the radio sensitivity.
2. The Q value of the magnetic antenna is significantly affected by the different positions of the coil windings. It can be seen from the experiment that the best position of the coil on the magnetic rod is 1/5 to 1/3 of the distance between the center of the coil winding length and the midpoint of the length of the magnetic rod. At this time, the movement of the coil has a large inductance change, and the directionality Yep.
3. The current flowing through the magnet coil is of high frequency. Due to the skin effect of high-frequency current, the resistance of the conductor to the high-frequency current increases with the increase of the current frequency, and as a result, the power loss of the wire to the high-frequency signal also increases. In order to overcome this, in the medium-wave range, the magnetic antenna coil is usually considered to increase the cross-sectional area of the conductor, that is, the enameled wire with a wire diameter of ∮0.1Mm is wound with 7 strands; 5mm silver-plated copper wires are wound between each other, and the distance between turns is generally 2-3mm.
4. Since the impedance of the tuning loop is high and the input impedance of the triode is low, the impedance matching problem is considered to maximize the signal output. The turns ratio of L1 and L2 is generally about 10:1, and L1 is usually 60 to 80 turns.
5. When using a magnetic antenna device, keep it away from magnetic fields (such as speakers, transformers, etc.). The stent should be made of non-metallic materials. The magnetic rod is easy to break, so be careful during use.
