First of all, pay attention to safety, avoid being burned by the welding pen, and the welding process should be meticulous. Secondly, different lines such as ABCD should be welded well. Finally, the horn line and the positive and negative electrode lines can be welded to the specified position.
For example, organic cast components, MOS integrated circuits, etc. Vulnerable components should be carefully tabled before weldingFace cleaning, tinning and other preparatory work, welding should not be repeated for a long time, and the iron head and temperature should be selected appropriately to ensure the success of a welding.
The integrated block generally has a notch at one end or a dot depression at one corner, and the pin is downward. If the notch is placed on the left, the lower left corner is 1 foot, and the upper left corner is the last foot, or the position of the dot is 1 foot. The circuit board is generally marked with a pin position or notch position, which can be inserted into the circuit board.
Component welding and installation: not only the correct position, but also reliable welding, beautiful shape. Before welding, see the resistance value and check it with a multimeterThe noise is intermittent, sometimes loud, sometimes low. These are related to the strength of the radio signal. The stronger the radio signal, the smaller the noise, such as listening to local radio noise is small, listening to foreign radio noise is large.
3, TX is a receiving antenna, C is a capacitor, CB is a variable capacitor, used to adjust the station, VD is two diodes, L1 is a magnetic bar, 3AG is a transistor, L3 is a choke, R1 is a resistor (can be adjusted according to the working state of the transistor), K is a switch, a long and short vertical line is a battery, plus headphones.
1, this is the circuit schematic and layout of the single chip FM radio using advanced electronic circuits and a new generation of highly integrated integrated circuit TDA7021T design, high sensitivity, small size, like BB machine, can be hung on the waistband or in the chest pocket, the use of a fifth battery, with tuning instructions, with a miniature earphone listening.
2, interference noise is intermittent, while loud, while small. These are related to the strength of the radio signal. The stronger the radio signal, the less noise, such as the receiverListen to local radio noise is low, listen to foreign radio noise is high. The solution to the noise is as follows: Adjust the direction of the radio to reduce the noise.
3, CD9088 can be composed of a variety of FM radio circuit, in addition to the use of electrical tuning to search the radio, can also use the traditional variable capacitor tuning search radio.
1, the ore radio circuit diagram and production method are as follows: Material preparation: paper tube, coil, tape, sandpaper, variable capacitor, twop>4, use copper wire to make an antenna and a ground wire, one end of the antenna (copper wire) is wrapped around the mosquito net pole, one end of the ground wire is inserted in the land, the two wires of the earphone are connected to the fixed (active) ore and then the sky, the ground wire, a simple ore radio is made.
5, the earliest ore radio used is variable inductance, because the variable inductance can be made by itself, the cost is low, but later all the radios are changed to variable capacitors, which can save the trouble of making, the circuit in Figure 1 is the use of variable capacitors.
6, the simplest ore radioAn aerial antenna of more than three meters, a ground wire, a 2AP9 diode, a high-resistance earphone, a diode and earphone connected to both ends of the earth and earth line, can only listen to the strongest local station, if there are multiple strong stations mixed together.
1, homemade DC tube three light radio tone is good, but the sound is not good with distortion, you can install a π filter in the output circuit, with twoA capacitor and a resistor do a filter circuit, so that the sound effect can be changed to sound better.
2, the line should be as short as possible, the shielded line must be used, the negative feedback should be increased to reduce the sensitivity, and the filter circuit should be improved.
3, there are many kinds of radio squeaking sound phenomenon, put the position, the signal is not good, the battery is insufficient, etc., the FM situation will be better, if the amplitude modulation is a normal phenomenon, the radio principle is generally relatively simple, but now the attention to small components, resulting in a lot of my own can not repair, of course, the price is cheap on the one hand.
4, you check the fault to start from the last level: turn on the volume, the small driver in turn touch the power amplifier tube, detection, voltage amplifier tube, the gate of the tube, there should be a large AC signal tone, if the level is not, it is the level is broken, and then further check what is the other bad.
5, first look at the tube radio circuit diagram (much the same as your radio) : the radio has a current sound, indicating that the power circuit of the machine, the power amplifier output circuit, are intact. Please check according to the following methods: Check whether the converter tube (6A2) and the central discharge tube (6k4) are inserted incorrectly according to the circuit diagram。< / p >