基于單片機(jī)數(shù)字電壓表電路設(shè)計(jì)外文文獻(xiàn)原稿和譯文

1、外文文獻(xiàn)原稿和譯文原 稿Front sideCopyright of this circuit belongs to smart kit electronics. In this page we will use this circuit to discuss for improvements and we will introduce some changes based on original schematicGeneral Description This is an easy to build, but nevertheless very accurate and useful di

2、gital voltmeter. It has been designed as a panel meter and can be used in DC power supplies or anywhere else it is necessary to have an accurate indication of the voltage present. The circuit employs the ADC (Analogue to Digital Converter) I.C. CL7107 made by INTERSIL. This IC incorporates in a 40 p

3、in case all the circuitry necessary to convert an analogue signal to digital and can drive a series of four seven segment LED displays directly. The circuits built into the IC are an analogue to digital converter, a comparator, a clock, a decoder and a seven segment LED display driver. The circuit a

4、s it is described here can display any DC voltage in the range of 0-1999 Volts. Technical Specifications - CharacteristicsSupply Voltage: . +/- 5 V (Symmetrical)Power requirements: . 200 mA (maximum)Measuring range: . +/- 0-1,999 VDC in four rangesAccuracy: . 0.1 %FEATURESSmall size Easy constructio

5、n Low cost.Simple adjustment.Easy to read from a distance.Few external components.How it Works In order to understand the principle of operation of the circuit it is necessary to explain how the ADC IC works. This IC has the following very important features:Great accuracy.It is not affected by nois

6、e.No need for a sample and hold circuit.It has a built-in clock.It has no need for high accuracy external components.Schematic (fixed 16-11-09)7-segment display pinout MAN6960An Analogue to Digital Converter, (ADC from now on) is better known as a dual slope converter or integrating converter. This

7、type of converter is generally preferred over other types as it offers accuracy, simplicity in design and a relative indifference to noise which makes it very reliable. The operation of the circuit is better understood if it is described in two stages. During the first stage and for a given period t

8、he input voltage is integrated, and in the output of the integrator at the end of this period, there is a voltage which is directly proportional to the input voltage. At the end of the preset period the integrator is fed with an internal reference voltage and the output of the circuit is gradually r

9、educed until it reaches the level of the zero reference voltage. This second phase is known as the negative slope period and its duration depends on the output of the integrator in the first period. As the duration of the first operation is fixed and the length of the second is variable it is possib

10、le to compare the two and this way the input voltage is in fact compared to the internal reference voltage and the result is coded and is send to the display.All this sounds quite easy but it is in fact a series of very complex operations which are all made by the ADC IC with the help of a few exter

11、nal components which are used to configure the circuit for the job. In detail the circuit works as follows. The voltage to be measured is applied across points 1 and 2 of the circuit and through the circuit R3, R4 and C4 is finally applied to pins 30 and 31 of the IC. These are the input of the IC a

12、s you can see from its diagram. (IN HIGH & IN LOW respectively). The resistor R1 together with C1 are used to set the frequency of the internal oscillator (clock) which is set at about 48 Hz. At this clock rate there are about three different readings per second. The capacitor C2 which is connected

13、between pins 33 and 34 of the IC has been selected to compensate for the error caused by the internal reference voltage and also keeps the display steady. The capacitor C3 and the resistor R5 are together the circuit that does the integration of the input voltage and at the same time prevent any div

14、ision of the input voltage making the circuit faster and more reliable as the possibility of error is greatly reduced. The capacitor C5 forces the instrument to display zero when there is no voltage at its input. The resistor R2 together with P1 are used to adjust the instrument during set-up so tha

15、t it displays zero when the input is zero. The resistor R6 controls the current that is allowed to flow through the displays so that there is sufficient brightness with out damaging them. The IC as we have already mentioned above is capable to drive four common anode LED displays. The three rightmos

16、t displays are connected so that they can display all the numbers from 0 to 9 while the first from the left can only display the number 1 and when the voltage is negative the - sign. The whole circuit operates from a symmetrical 5 VDC supply which is applied at pins 1 (+5 V), 21 (0 V) and 26 (-5 V)

17、of the IC.Construction First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the variou

18、s components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is

19、tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and also makes soldering easier.Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very

20、difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times. For this purpose come very handy specially made sponges that are kept wet and

21、 from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it.DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one tha

22、t contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux,

23、 as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work.In order to solder a component correctly you should do the following:Clean the component leads with a small piece of emery paper.Bend them at the correct distance from the components body and in

24、sert the component in its place on the board.You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board. In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make solde

25、ring difficult afterwards.Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board.When the solder starts to melt and flow wait till it covers

26、evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and allow the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of th

27、e joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it.Take

28、care not to overheat the tracks as it is very easy to lift them from the board and break them.When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the compo

29、nent.Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together.When you finish your work, cut off the excess of the component leads and clean the board thoroughly with a suit

30、able solvent to remove all flux residues that may still remain on it.0 - 2 V . R3 = 0 ohm 1%0 - 20 V . R3 = 1.2 Kohm 1%0 - 200 V . R3 = 12 Kohm 1%0 - 2000 V . R3 = 120 Kohm 1%When you have finished all the soldering on the board and you are sure that everything is OK you can insert the IC in its pla

31、ce. The IC is CMOS and is very sensitive to static electricity. It comes wrapped in aluminium foil to protect it from static discharges and it should be handled with great care to avoid damaging it. Try to avoid touching its pins with your hands and keep the circuit and your body at ground potential

32、 when you insert it in its place. Connect the circuit to a suitable power supply 5 VDC and turn the supply on. The displays should light immediately and should form a number. Short circuit the input (0 V) and adjust the trimmer P1 until the display indicates exactly 0.If it does not work Check your

33、work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. Check again all the external connections to and from the circuit to see if there is a mistake there.See that there are no components missing or inserted in the wrong places. Make sure

34、 that all the polarised components have been soldered the right way round.Make sure the supply has the correct voltage and is connected the right way round to your circuit. - Check your project for faulty or damaged components.Sample Power supply 1Sample Power Supply 2 譯 文引言這是一個(gè)很容易建立并且非常準(zhǔn)確和有用的數(shù)字電壓表。

35、它被設(shè)計(jì)成一個(gè)面板儀表，可用于直流電源供應(yīng)器或其他需要有一個(gè)準(zhǔn)確電壓指示的地方。該電路采用的ADC（模擬數(shù)字轉(zhuǎn)換器）集成電路CL7107由Intersil公司生產(chǎn)。該IC采用40引腳的情況下整合了所有必要的電路模擬信號(hào)轉(zhuǎn)換為數(shù)字，可以直接驅(qū)動(dòng)4個(gè)7段LED顯示。在IC中內(nèi)置的電路是數(shù)字轉(zhuǎn)換器，比較器，一個(gè)時(shí)鐘，一個(gè)解碼器和一個(gè)7段LED顯示驅(qū)動(dòng)器模擬。在這里它描述了一個(gè)可以顯示在0-1999電壓范圍的直流電壓電路。LED顯示屏數(shù)字電壓表技術(shù)規(guī)格 - 特征電源電壓：.+ / - 5V（對(duì)稱）。電源要求：.200mA（最大）。測(cè)量范圍：.+ / - 0-1,999V在四個(gè)范圍。精度：.0.1。特征

36、：小尺寸。簡(jiǎn)易建筑。成本低。簡(jiǎn)單的調(diào)整。易于讀取距離。很少的外部元件。數(shù)字電壓表的基本原則為了了解電路的運(yùn)作的原則，說明ADC的集成電路工程是必要的。該集成電路具有以下非常重要的特點(diǎn)：準(zhǔn)確性?？垢蓴_性。無需要一個(gè)采樣保持電路。它有一個(gè)內(nèi)置的時(shí)鐘。它不需要精度高的外部元件。一個(gè)模擬數(shù)字轉(zhuǎn)換器(ADC)，從現(xiàn)在起更好的稱為雙斜率轉(zhuǎn)換器或集成轉(zhuǎn)換器。這種類型的轉(zhuǎn)換器通常優(yōu)于其他類型，因?yàn)樗峁┝藴?zhǔn)確，簡(jiǎn)潔的設(shè)計(jì)和它可以將相對(duì)不重要的噪音變得非?？煽俊Ｈ绻麑㈦娐贩謨蓚€(gè)階段描述，該電路的操作將更好的理解。在第一階段的輸入集成電壓和最后階段的輸出集成電壓中有一個(gè)電壓與輸入電壓成正比。在預(yù)設(shè)的時(shí)間結(jié)束時(shí)，積

37、分將到達(dá)內(nèi)部基準(zhǔn)電壓以及輸出電路會(huì)逐漸降低直至達(dá)到零參考電壓水平。第二個(gè)階段就是所謂的負(fù)斜率時(shí)期，其持續(xù)時(shí)間由第一階段積分器輸出而定。作為第一個(gè)操作時(shí)間是固定的，第二個(gè)變量的長度就可以比較兩個(gè)這樣的輸入電壓，其實(shí)是相對(duì)于內(nèi)部參考電壓，其結(jié)果是編碼，然后發(fā)送到顯示。示意圖（固定16-11-09）7段顯示器引出線MAN6960這一切聽起來很容易，但實(shí)際上它是一系列非常復(fù)雜的操作，這些都是由ADC集成電路作出了很少的外部元件，幫助它們用來配置工作的電路。詳細(xì)的電路的工作原理如下。為了進(jìn)行測(cè)量，需要將電壓施加于電路的1和2點(diǎn)，最后通過電路的R3，R4和C4應(yīng)用到集成電路的引腳30和31。從下圖你可知這

38、是該集成電路的輸入(分別為高與低)。R1電阻的C1一起用來設(shè)置內(nèi)部振蕩器(時(shí)鐘)，該設(shè)置約48Hz。在這個(gè)時(shí)鐘速率大約有三個(gè)不同的每秒讀數(shù)。連接集成電路引腳33和34之間的電容已被選定，以彌補(bǔ)由內(nèi)部參考電壓帶來的誤差，并保持穩(wěn)定的顯示。電容C3和電阻R5在一起的電路是輸入電壓的集成電路，同時(shí)它可避免任何使電路更快的分裂輸入電壓，從而使錯(cuò)誤的可能性大大減少進(jìn)而使電路更穩(wěn)定。在沒有輸入電壓時(shí)電容器C5強(qiáng)迫儀器顯示為零。當(dāng)輸入為零時(shí)電阻R2和P1一起用來調(diào)整儀器在設(shè)置過程中顯示為零。電阻R6的控制電流允許流經(jīng)顯示，以便使電路在沒有損壞的前提下顯示充分的亮度。至于我們上面已經(jīng)提到的芯片它能夠驅(qū)動(dòng)4個(gè)共

39、陽極LED顯示屏。這三個(gè)最右邊的顯示器相連，使他們可以顯示所有從0到9的數(shù)字，而從左邊第一個(gè)只能顯示數(shù)字1，當(dāng)電壓為負(fù)“-”的時(shí)候。整個(gè)電路工作，從對(duì)稱5伏直流電電源，這在引腳1(+5V)申請(qǐng)，21(0V)，26(-5V)集成電路。數(shù)字電壓表印刷電路板的加工首先讓我們考慮建立一個(gè)印刷電路板上的電子電路的基礎(chǔ)知識(shí)。該印刷電路板是由薄絕緣銅的導(dǎo)電復(fù)合材料薄層形成，這樣以形成電路之間的各組成部分的必要的導(dǎo)體。一個(gè)設(shè)計(jì)完善的印刷電路板是非?？扇〉?，因?yàn)樗蟠蠹涌炝思庸?，并大大減少了決策失誤的可能性。為了保護(hù)印刷電路板在存儲(chǔ)過程中被氧化和保證它到達(dá)你所要求的完美的條件，在生產(chǎn)過程中將銅鍍錫的同時(shí)起表面還要覆蓋一層特殊的漆，這樣不僅防止了它被氧化，也使焊接更容易。焊接的部件，印刷電路板是建立你的電路的唯一的方式和你在做