LONG LIFE BATTERY-If small breaks are found in individual copper foil strips
If small breaks are found in individual copper foil strips
If small breaks are found in individual copper foil strips, they can be easily repaired with an electric soldering iron and a short length of wire.Figs. 3 - 6 show the fracture of the conductive copper foil of the printed circuit board.When repairing, the sundries such as anti-corrosion ink, oil stain or dust on the copper surface on both sides of the fracture can be carefully removed. This can be done by lightly scraping the copper foil strip surface with a small rotary chisel. Care should be taken not to scrape too much so as to prevent the copper foil from separating from the substrate.The copper foil strips on both sides of the fracture should be polished, then tin coated on the surface of the copper foil strip with an electric soldering iron and a small amount of solder, and then a bare wire should be bridged over the fracture and welded firmly with the electric soldering iron.Finally, an ohmmeter is used to test whether the welding is good.
After processing, the copper foil strips left on the printed circuit poles should match the wiring diagram drawn on the paper first.If there is no match, check them carefully to see where the mistakes are and correct them immediately if possible.However, this is only possible if there is still excess wire foil on the printed circuit board.If more copper foil strips are etched away, they can only be scrapped and reworked, or the missing parts can be filled up with insulated wires.
Although the processing of printed circuit boards is complicated, it is much easier than wiring on drilled circuit boards, and since each component is fixed, the printed circuit boards provide an extremely stable base for the components.In other types of circuits, the connecting lines between the components are loose.
For those circuits used to control frequency or other critical parameters, if the components in the circuit move slightly, an offset or " drift" will occur.The components assembled with printed circuit boards have high stability, so this assembly technology can be used in occasions where high stability of components is required.It should be noted that all circuits in this book can be mounted on the drilling circuit board if appropriate fabrication techniques are used.The production of printed circuits requires some experience, which is not suitable for those who lack production experience.
For example, readers should be encouraged to use printed circuit boards for future design and accumulate manufacturing experience.However, if the drilling circuit board is used for manufacturing, it can also be successful.
The circuits used in this book are transistor, diode, integrated circuit, resistor, capacitor and photosensitive element.To assemble these components into an electronic circuit, and to make it work successfully and continuously, certain skills and tools are needed.Pay close attention to neatness during fabrication to avoid short circuit between component leads.If electronic components are hastily soldered, sometimes the circuit may work normally, but most of them will fail or work normally at first, but problems will arise after a period of work.If the connection is not arranged in advance but where it is received, it will end up losing three to four and which line should be received by which contact.Therefore, a plan must be made before the actual production can begin.For this reason, a recommended component arrangement ( layout ) will be provided in every future electronic circuit design, although it is not necessary to completely copy it, but this will enable readers to be sure.The position of each basic element in the fixed circuit is arranged as a reference.Adhering to this plan established the continuity of the work from the beginning and helped to carry it through to the end.
The author does not want to restrict readers from making only some circuits in this book. In fact, if they are willing to do experiments, they should be encouraged to do more or less, but the experiments should be carried out step by step.The continuity of work is still needed when the reader makes it according to his own design or not according to the arrangement of components recommended by Hui.
The components are mounted on the circuit board in two ways: horizontally and vertically.In both mounting methods, the leads of the components are inserted into the holes of the circuit board, and all the leads are soldered on the back of the board.The most commonly used of these two mounting methods is horizontal mounting. Figure 3 - 7 shows an example of horizontal mounting of components on a circuit board.In this figure, elements such as resistors and capacitors are mounted parallel to the length of the circuit board, with leads passing through two holes spaced close to the length of the elements.This installation method is suitable for beginners.When the leads of the components are installed through the circuit board, the leads are wound with the leads and connecting wires of other components before soldering.The horizontal installation tiles the components so they take up more space than the vertical installation.The advantage is that the circuit looks clear at a glance.
The standard mounting method of the second component on the circuit board is vertical mounting, as shown in fig. 3 - 8.Each component is mounted perpendicular to the surface of the circuit board.The two leads of each component also penetrate into the holes of the circuit board, but the spacing of the holes is only a fraction of that of the horizontal mounting.Since the vertical space on the upper part of the circuit board can be used, the circuit board used for the same circuit is much smaller than that used for horizontal mounting.
The disadvantage of vertical mounting is to allow more component leads to be exposed on the circuit board, which tends to cause the component leads to collide and short - circuit.Therefore, the part of the lead that leads down the component from the top of the component to the circuit board is often insulated.In welding to every 0.°