Basic Tools Section 1 Multimeters The current multimeters are divided into analog and digital. They have their own convenience. It is difficult to say who is good or bad, and it is best to have a pointer and a digital one. Amateur electronic production has a pointer type MF30 multimeter, which is a classic model. There are also veteran MF500 multimeters, cheap MF50 multimeters, generally available at the telecommunications store.
The three basic functions of the multimeter are to measure resistance, voltage, and current, so the older generation called it a three-purpose meter. Today's multimeter adds a lot of new features, especially digital multimeters, such as measuring capacitance, transistor amplification, diode drop, etc., and even a talking digital multimeter that can broadcast measurement results in a language. (In fact, it's not that hard. Bitbaby once wanted to use MCU and voice circuit to do it one by one :-)
Digital multimeter also has many classic models, such as DT830C, DT830C, DT890D, etc., behind the suffix shows the functional difference, which DT830C has bought more than 30 yuan a, cheap enough. Bitbaby installed an MF50 multimeter in school. The circuit principle is not complicated. Only so many components are not fixed on the printed board, but they are directly soldered on the terminal board. Their installation is still troublesome for beginners.
The biggest feature of the multimeter is that there is a range changeover switch, and each function is switched by this switch. Basically, A- is used to represent the measured DC current. The general milliampere and Ampere stalls are divided into several levels. V- indicates DC voltage measurement. The advanced multimeter has a millivolt range, and the voltage range is also divided into several levels. V~ is used to measure AC voltage. A ~ test AC current.
Ω ohms measured resistance, for the pointer multimeter, once again change the resistance file to do a zero. Zero adjustment is to put the multimeter's red and black table pens together, and then turn the zero button so that the pointer points to the zero position. hFE measures the current amplification factor of the triode. The value of hFE can be measured by simply inserting the three pins of the triode into the corresponding holes on the universal surface plate. Note that PNP and NPN are different.
The following uses the MF30 multimeter as an example to illustrate the reading of the multimeter. The first tick mark is the resistance value indication. The leftmost end is infinity and the right end is zero, and the scale is uneven. There are R×1, R×10, R×100, R×1K, and R×10K files in the resistance range, indicating that the indication of the scale must be multiplied by the multiple, to obtain the actual resistance value (in ohms).
For example, if a resistance is measured with R×100, and the pointer indicates “10â€, then its resistance value is 10×100=1000, which is 1K. The second tick mark is shared between the 500V file and the 500mA file. It should be noted that the indication principle of the voltage file and the current file is different from the resistance file. For example, the 5V file means that the file can only measure the voltage below 5V, and the 500mA file can only measure 500mA. The following current, if it exceeds the range, will damage the multimeter.
Note: The multimeter should be placed horizontally when used. The red meter pen is inserted in the + hole and the black meter pen is inserted in the hole. The test current uses the current file, but it cannot use the voltage file or the electric blockage. The same applies. Otherwise, the fuse in the meter is burned, and the meter is damaged. If you do not know the range beforehand, try measuring with the largest range, then disconnect the measuring circuit and then shift the gear. Do not change the range while online. When the hands are rapidly deflected to the bottom, the circuit should be disconnected immediately for inspection.
Finally there is a rule, that is, after the appointment of the multimeter to switch the range switch to the highest level of AC voltage, to prevent people from inadvertently measuring the 220V mains voltage and damage. Remember the fine tradition left by this old predecessor!
Regarding the use of digital multimeters, there is an article reprinted from "Radio".
The technique for checking components with a multimeter will be described in detail elsewhere.
Here are some pictures of the multimeter:
MF110 MF500 MF50 MF47
DT830B DT890
The second section of electric iron electric iron is divided into external heat type and internal heat type, external heat type of general power are larger.
Internally heated solder irons are small and inexpensive. General electronic production uses 20W-30W internal heating type electric iron. Of course there is a 50W external heating type soldering iron that can be prepared. The internal heating type electric iron has a higher heating efficiency, and it is also more convenient to replace the iron head.
Soldering iron is used for soldering. For the sake of convenience, it is usually made of “solder wireâ€. Solder wire generally contains flux-supporting rosin. Solder wire uses approximately 60% tin and 40% lead, with a lower melting point. (Bitbaby has a good habit is to wash your hands after every job. Lead is not a good thing. Rosin is quite familiar:-)
Rosin is a kind of flux, which can help welding. People who pull erhu are sure to have it, and they can also buy it from pharmacies. Rosin can be used directly, or it can be configured as a rosin solution. It is to grind the rosin, put it in a vial, and then add alcohol to mix it. Note that alcohol is volatile and remember to tighten the cap after use. A small piece of cotton can be placed in the bottle. When it is used, it is clamped with tweezers and applied on the printing plate or components.
Note that there is a solder paste on the market, which is a kind of corrosive material. It is used in industry and is not suitable for electronic production. There is also pine perfume on the market, not the rosin solution we used here.
The soldering iron is pinched in the hand and must be used with care. The newly purchased soldering iron should first check the resistance value between the plug and the metal case with the multimeter resistance file, and the pointer of the multimeter should not move. Otherwise it should be thoroughly checked.
Recently produced internal heat type soldering iron, manufacturers in order to save costs, the power cord does not use a rubber line, but directly with plastic wires, relatively unsafe. It is highly recommended to use a rubber wire because it is not as prone to scalding, damage, short circuit or electric shock as plastic wires.
Before using the new electric iron, use a trowel to pick the tip of the soldering iron. After the power is turned on, the color of the soldering iron will change. This will prove that the soldering iron has become hot, and then the soldering iron is placed on the tip of the soldering iron and tin plated. Not easily oxidized. In use, the tip should be kept clean, and soldering iron should always be on the tip of the soldering iron.
When using a soldering iron, if the temperature of the soldering iron is too low, the solder cannot be melted or the solder joint is not completely melted, making it unsightly and unreliable. Too high will make the iron "burnt" (though the temperature is high, it cannot be tinned). In addition, it is also necessary to control the welding time. The time for the soldering iron to stay is too short. The solder is not easy to be completely melted and contacted to form a "cold solder". The soldering time is too long and it can easily damage the components or make the copper foil of the printed circuit board. Tilt up.
Usually a solder joint is soldered in one or two seconds. If it is not completed, it will wait for a while to solder. When the soldering iron cannot be moved during soldering, the position of the solder joint should be selected first, and then the solder bump should be used to contact the solder joint.
Section III. Printed Circuit Boards Printed circuit boards are a big part of electronic production, and they are also the technologies that best represent the level of electronics enthusiasts. Printed circuit boards are referred to as printed boards for short, and factory production is very different from amateur production. The factory generally designs the printed board diagram according to the circuit schematic provided by the customer, and then makes the printed board through photolithography and other techniques, and then forms the finished product by soldering, printing, etc., and requires a series of equipment.
In the traditional amateur production, printed boards can only be produced using a copper-plated and corrosive solution. In recent years, new types of technologies such as universal test boards and photosensitive circuit boards have been introduced to liberate vast numbers of electronics enthusiasts and electronic product developers. In addition to the popularity of PCs, designing circuits with CAD software and automatically generating PCBs (printed circuit boards) are not difficult. It is even more convenient to print on the film directly with the photosensitive circuit board.
Bitbaby learned ORCAD software in the school curriculum and used it to design a typical application circuit for the 8031 ​​microcontroller. It feels really good. The teacher is also not allowed to use ORCAD's automatic routing function. The figure of Bitbaby's manual wiring can be beautiful, and the corners of the traces are smooth transitions. Taking full account of this design makes the printing plate stronger, so that the teacher thinks that the wiring is automatic. It (not blowing :-). Unfortunately, no printer printed out the PCB at that time.
PROTEL is known to most electronic enthusiasts, but unfortunately Bitbaby has not studied it deeply. General electronic production circuit is not complicated, for the veteran, as long as you can use the brain to design a printed circuit board diagram, so talk about the traditional production method of printed board.
First, design the printed circuit board diagram on the basis of the circuit schematic diagram on the paper, the correct connection among each component is important, but also pay attention to the size of the components, arrangement position, interference and so on. (Bitbaby will later write a special article on how to design the printed board.) After the design is completed, the schematics should be re-checked, and the components should be placed in their respective positions to adjust the hole spacing and alignment. Pay attention to the positive and negative, and sometimes accidentally design the opposite side. You can write the original image on carbon paper once. Then you have what you need on the back of the paper.
Bitbaby's method of making a printed circuit board is to cut out the designed 1:1 drawing, attach it to the copper surface of the single-faced copper-clad board with transparent glue, and then punch it in the place where the hole is drilled to form a recess. The pit, so that drilling with a small electric drill will not slip. Then use a self-made small electric drill (recording machine motor modification) to drill holes, tear off the drawings after all finishes, and paint directly with a brush.
Since holes are already positioned, it is not difficult to draw, just remember that the holes are connected together. Generally uncomplicated circuits use this method to make the circuit board extremely fast (even if the copying paper is saved :-). If the complicated circuit can insert a copy of carbon paper between the drawing and the copper-clad board, then the printed circuit board drawing will be described again. Place the hole deeper, and then use a brush to paint the line.
If there is no paint, trace lines can be traced with a better quality marker, or traced with a correction fluid, but the circuit board for correcting the fluid profile is not very beautiful, and the width of the circuit needs to be corrected after drying. Nail polish can also be used, dried faster and easier to use than correction fluid. During the tracing, pay attention to the distance between the lines, and surround the holes to form a circle to facilitate welding.
It takes a long time for the paint to dry. After the paint is dry, it can be put into the corrosive solution. The corrosive solution is generally made of ferric chloride and water. The ferric chloride is a yellowish solid and it is easy to absorb the moisture in the air. So Should be sealed and stored. When ferric chloride solution is used, 40% of ferric chloride and 60% of water are generally used. Of course, more ferric chloride is used, or warm water (not hot water to prevent paint shedding) can make the reaction faster. .
Note that ferric chloride has a certain degree of corrosivity and it is best not to get it on the skin or clothes (difficult to wash :-( reaction containers with cheap plastic basins, just like the circuit board. Corrosion is from the edge In the beginning, when the unpainted copper foil is corroded, the circuit board should be taken out in time to prevent the paint from falling off and eroding the useful circuit.
Rinse with clean water at this time, and scrape off the paint with bamboo or other materials (the paint comes out of the liquid and is easier to remove). If it is not easy to scratch, just use hot water. Then wipe dry and polish it with sandpaper to reveal shiny copper foil. A printed circuit board is ready. In order to preserve the results, Bitbaby usually coats the polished circuit board with rosin solution, which can both help the solder and prevent oxidation.
The three basic functions of the multimeter are to measure resistance, voltage, and current, so the older generation called it a three-purpose meter. Today's multimeter adds a lot of new features, especially digital multimeters, such as measuring capacitance, transistor amplification, diode drop, etc., and even a talking digital multimeter that can broadcast measurement results in a language. (In fact, it's not that hard. Bitbaby once wanted to use MCU and voice circuit to do it one by one :-)
Digital multimeter also has many classic models, such as DT830C, DT830C, DT890D, etc., behind the suffix shows the functional difference, which DT830C has bought more than 30 yuan a, cheap enough. Bitbaby installed an MF50 multimeter in school. The circuit principle is not complicated. Only so many components are not fixed on the printed board, but they are directly soldered on the terminal board. Their installation is still troublesome for beginners.
The biggest feature of the multimeter is that there is a range changeover switch, and each function is switched by this switch. Basically, A- is used to represent the measured DC current. The general milliampere and Ampere stalls are divided into several levels. V- indicates DC voltage measurement. The advanced multimeter has a millivolt range, and the voltage range is also divided into several levels. V~ is used to measure AC voltage. A ~ test AC current.
Ω ohms measured resistance, for the pointer multimeter, once again change the resistance file to do a zero. Zero adjustment is to put the multimeter's red and black table pens together, and then turn the zero button so that the pointer points to the zero position. hFE measures the current amplification factor of the triode. The value of hFE can be measured by simply inserting the three pins of the triode into the corresponding holes on the universal surface plate. Note that PNP and NPN are different.
The following uses the MF30 multimeter as an example to illustrate the reading of the multimeter. The first tick mark is the resistance value indication. The leftmost end is infinity and the right end is zero, and the scale is uneven. There are R×1, R×10, R×100, R×1K, and R×10K files in the resistance range, indicating that the indication of the scale must be multiplied by the multiple, to obtain the actual resistance value (in ohms).
For example, if a resistance is measured with R×100, and the pointer indicates “10â€, then its resistance value is 10×100=1000, which is 1K. The second tick mark is shared between the 500V file and the 500mA file. It should be noted that the indication principle of the voltage file and the current file is different from the resistance file. For example, the 5V file means that the file can only measure the voltage below 5V, and the 500mA file can only measure 500mA. The following current, if it exceeds the range, will damage the multimeter.
Note: The multimeter should be placed horizontally when used. The red meter pen is inserted in the + hole and the black meter pen is inserted in the hole. The test current uses the current file, but it cannot use the voltage file or the electric blockage. The same applies. Otherwise, the fuse in the meter is burned, and the meter is damaged. If you do not know the range beforehand, try measuring with the largest range, then disconnect the measuring circuit and then shift the gear. Do not change the range while online. When the hands are rapidly deflected to the bottom, the circuit should be disconnected immediately for inspection.
Finally there is a rule, that is, after the appointment of the multimeter to switch the range switch to the highest level of AC voltage, to prevent people from inadvertently measuring the 220V mains voltage and damage. Remember the fine tradition left by this old predecessor!
Regarding the use of digital multimeters, there is an article reprinted from "Radio".
The technique for checking components with a multimeter will be described in detail elsewhere.
Here are some pictures of the multimeter:
MF110 MF500 MF50 MF47
DT830B DT890
The second section of electric iron electric iron is divided into external heat type and internal heat type, external heat type of general power are larger.
Internally heated solder irons are small and inexpensive. General electronic production uses 20W-30W internal heating type electric iron. Of course there is a 50W external heating type soldering iron that can be prepared. The internal heating type electric iron has a higher heating efficiency, and it is also more convenient to replace the iron head.
Soldering iron is used for soldering. For the sake of convenience, it is usually made of “solder wireâ€. Solder wire generally contains flux-supporting rosin. Solder wire uses approximately 60% tin and 40% lead, with a lower melting point. (Bitbaby has a good habit is to wash your hands after every job. Lead is not a good thing. Rosin is quite familiar:-)
Rosin is a kind of flux, which can help welding. People who pull erhu are sure to have it, and they can also buy it from pharmacies. Rosin can be used directly, or it can be configured as a rosin solution. It is to grind the rosin, put it in a vial, and then add alcohol to mix it. Note that alcohol is volatile and remember to tighten the cap after use. A small piece of cotton can be placed in the bottle. When it is used, it is clamped with tweezers and applied on the printing plate or components.
Note that there is a solder paste on the market, which is a kind of corrosive material. It is used in industry and is not suitable for electronic production. There is also pine perfume on the market, not the rosin solution we used here.
The soldering iron is pinched in the hand and must be used with care. The newly purchased soldering iron should first check the resistance value between the plug and the metal case with the multimeter resistance file, and the pointer of the multimeter should not move. Otherwise it should be thoroughly checked.
Recently produced internal heat type soldering iron, manufacturers in order to save costs, the power cord does not use a rubber line, but directly with plastic wires, relatively unsafe. It is highly recommended to use a rubber wire because it is not as prone to scalding, damage, short circuit or electric shock as plastic wires.
Before using the new electric iron, use a trowel to pick the tip of the soldering iron. After the power is turned on, the color of the soldering iron will change. This will prove that the soldering iron has become hot, and then the soldering iron is placed on the tip of the soldering iron and tin plated. Not easily oxidized. In use, the tip should be kept clean, and soldering iron should always be on the tip of the soldering iron.
When using a soldering iron, if the temperature of the soldering iron is too low, the solder cannot be melted or the solder joint is not completely melted, making it unsightly and unreliable. Too high will make the iron "burnt" (though the temperature is high, it cannot be tinned). In addition, it is also necessary to control the welding time. The time for the soldering iron to stay is too short. The solder is not easy to be completely melted and contacted to form a "cold solder". The soldering time is too long and it can easily damage the components or make the copper foil of the printed circuit board. Tilt up.
Usually a solder joint is soldered in one or two seconds. If it is not completed, it will wait for a while to solder. When the soldering iron cannot be moved during soldering, the position of the solder joint should be selected first, and then the solder bump should be used to contact the solder joint.
Section III. Printed Circuit Boards Printed circuit boards are a big part of electronic production, and they are also the technologies that best represent the level of electronics enthusiasts. Printed circuit boards are referred to as printed boards for short, and factory production is very different from amateur production. The factory generally designs the printed board diagram according to the circuit schematic provided by the customer, and then makes the printed board through photolithography and other techniques, and then forms the finished product by soldering, printing, etc., and requires a series of equipment.
In the traditional amateur production, printed boards can only be produced using a copper-plated and corrosive solution. In recent years, new types of technologies such as universal test boards and photosensitive circuit boards have been introduced to liberate vast numbers of electronics enthusiasts and electronic product developers. In addition to the popularity of PCs, designing circuits with CAD software and automatically generating PCBs (printed circuit boards) are not difficult. It is even more convenient to print on the film directly with the photosensitive circuit board.
Bitbaby learned ORCAD software in the school curriculum and used it to design a typical application circuit for the 8031 ​​microcontroller. It feels really good. The teacher is also not allowed to use ORCAD's automatic routing function. The figure of Bitbaby's manual wiring can be beautiful, and the corners of the traces are smooth transitions. Taking full account of this design makes the printing plate stronger, so that the teacher thinks that the wiring is automatic. It (not blowing :-). Unfortunately, no printer printed out the PCB at that time.
PROTEL is known to most electronic enthusiasts, but unfortunately Bitbaby has not studied it deeply. General electronic production circuit is not complicated, for the veteran, as long as you can use the brain to design a printed circuit board diagram, so talk about the traditional production method of printed board.
First, design the printed circuit board diagram on the basis of the circuit schematic diagram on the paper, the correct connection among each component is important, but also pay attention to the size of the components, arrangement position, interference and so on. (Bitbaby will later write a special article on how to design the printed board.) After the design is completed, the schematics should be re-checked, and the components should be placed in their respective positions to adjust the hole spacing and alignment. Pay attention to the positive and negative, and sometimes accidentally design the opposite side. You can write the original image on carbon paper once. Then you have what you need on the back of the paper.
Bitbaby's method of making a printed circuit board is to cut out the designed 1:1 drawing, attach it to the copper surface of the single-faced copper-clad board with transparent glue, and then punch it in the place where the hole is drilled to form a recess. The pit, so that drilling with a small electric drill will not slip. Then use a self-made small electric drill (recording machine motor modification) to drill holes, tear off the drawings after all finishes, and paint directly with a brush.
Since holes are already positioned, it is not difficult to draw, just remember that the holes are connected together. Generally uncomplicated circuits use this method to make the circuit board extremely fast (even if the copying paper is saved :-). If the complicated circuit can insert a copy of carbon paper between the drawing and the copper-clad board, then the printed circuit board drawing will be described again. Place the hole deeper, and then use a brush to paint the line.
If there is no paint, trace lines can be traced with a better quality marker, or traced with a correction fluid, but the circuit board for correcting the fluid profile is not very beautiful, and the width of the circuit needs to be corrected after drying. Nail polish can also be used, dried faster and easier to use than correction fluid. During the tracing, pay attention to the distance between the lines, and surround the holes to form a circle to facilitate welding.
It takes a long time for the paint to dry. After the paint is dry, it can be put into the corrosive solution. The corrosive solution is generally made of ferric chloride and water. The ferric chloride is a yellowish solid and it is easy to absorb the moisture in the air. So Should be sealed and stored. When ferric chloride solution is used, 40% of ferric chloride and 60% of water are generally used. Of course, more ferric chloride is used, or warm water (not hot water to prevent paint shedding) can make the reaction faster. .
Note that ferric chloride has a certain degree of corrosivity and it is best not to get it on the skin or clothes (difficult to wash :-( reaction containers with cheap plastic basins, just like the circuit board. Corrosion is from the edge In the beginning, when the unpainted copper foil is corroded, the circuit board should be taken out in time to prevent the paint from falling off and eroding the useful circuit.
Rinse with clean water at this time, and scrape off the paint with bamboo or other materials (the paint comes out of the liquid and is easier to remove). If it is not easy to scratch, just use hot water. Then wipe dry and polish it with sandpaper to reveal shiny copper foil. A printed circuit board is ready. In order to preserve the results, Bitbaby usually coats the polished circuit board with rosin solution, which can both help the solder and prevent oxidation.