The basic principle requires a printed circuit board design

- Aug 05, 2016-

1. Printed circuit board design from the beginning to determine the size of the plate, due to the size of the printed circuit board chassis shell size limit, just to be able to install into the housing is appropriate, secondly, to consider the printed circuit board and external components (mainly potentiometer, jack or another printed circuit board) connections. Printed circuit board and an external component is typically connected through a metal wire or plastic wire isolation. But sometimes designed to form the socket. Namely: the device installed in a plug-in printed circuit board set aside to act as a contact position jacks. For larger components are mounted on a printed circuit board, to increase the fixed metal accessories to enhance resistance to vibration, impact resistance.

2. Wiring diagram of the basic method first need to understand the design of the selected components and various socket specifications, size, area and so there is complete; on the placement of the various components to make a reasonable, careful consideration, mainly from the electromagnetic compatibility, interference angle, traces short, cross-less, power, ground path and decoupling and other considerations. After each component position fix is to connect the various components of the circuit diagram in accordance with the relevant connection pins, to complete a variety of methods, design of printed circuit diagram of computer-aided design and manual design two ways. The most original is hand-arranged layout. This is more cumbersome, often repeated several times in order to finalize, it can also be used when no other drawing device, such a manual alignment layout method just learning the printing plate map designers also helpful. Computer Aided Drafting, there are now a variety of graphics software, different functions, but in general, drawing, modifying more convenient and can save storage and printing. Next, the printed circuit board to determine the desired size, press schematics, initially identified the location of each component down, and then through constant adjustments to make more rational layout, the printed circuit board wiring arrangement of each element is as follows:

(1) are not allowed in the printed circuit cross circuit, may cross the line, you can use the "drill", "around" two kinds of solutions. That is, let the lead from a gap at the other resistors, capacitors, transistors at the foot of the "drill" in the past, or may cross from one end of a certain wire of "around" in the past, how the circuit is very complicated in exceptional circumstances, in order to simplify the design allow jumper wire, cross circuit to solve the problem.

(2) resistors, diodes, capacitors and other tubular element of "vertical", "horizontal" two installation methods. Vertical refers to the body member perpendicular to the circuit board mounting, welding, and the advantage is to save space, the horizontal component refers generally parallel and close to the circuit board mounting, welding, mechanical strength and the advantage of the preferred mounting member. These two different elements of the installation, the printed circuit board element pitch is not the same.

(3) with a circuit ground point should be as close as possible, and the power supply filter capacitor of the present stage of the circuit should also be connected to the level of the ground. In particular, the level of the transistor base, emitter ground not too far away, otherwise it will be too long because the copper foil ground between the two cause interference with the self-excited, with such "point ground method," the circuit, the more work stability, not self-excited.

(4) Total ground must be in strict accordance with the high frequency - IF - a low-level press weak to strong electric order principle, must not just repetitious random access, inter-stage and grade wiring can be rather long point, to comply with this provision. In particular frequency head, playback head, FM head ground wire arrangement requires more stringent, if inappropriate will produce self that does not work. FM frequency circuit class is often used large wraparound ground, in order to ensure good shielding effect. (5) strong current lead (common ground, amplifier power leads, etc.) should be as wide and more, in order to reduce wiring resistance and voltage drop can be reduced parasitic coupling generated by self-excitation.

(6) high impedance traces short, low impedance traces can be longer because of the high impedance traces prone flute and absorption signals, causing circuit instability. Power lines, ground, no feedback element base alignment emitter lead and so are low-impedance traces emitter follower base alignment, tape recorders ground two channels must be separated into their own way until the end of the effect and then together, such as two-way ground wire to connect to, easy to produce crosstalk, the separation decreased.

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