【正文】 can mean each unit function. The important mission of the project choice is according to control of knowledge and data, aim at the mission that the system put forward, request and condition, the function design of pletion to presume quest in this process, brave innovation, work hard for to attain the design project reasonable, credibility, economy, the function is wellfound, technique the other party case want to continuously carry on a possibility with defective analysis, finally design a plete frame diagram have to the correct reflection should plete of mission with each constitute part of functions, make clear system of basic constitute with correlation. Three. The design of unit electric circuit, parameter calculation and period choose According to index sign and function frame diagram of system, definitely each parts of mission, carry on the design of each unit electric circuit, parameter calculation and spare part choose.1. The unit electric circuit designThe unit electric circuit is the whole machine of one part, only make the each unit electric circuit design raise the whole machine design level so then can. Each unit electric circuit design ago all needed the mission of each unit electric circuit definitely, draft a function index sign of unit electric circuit in detail, with in front and back the relation of class, analyze constitute of electric circuit a concretely designing, the forerunner39。二、 方案選擇　　這一步的工作要求是把系統(tǒng)要完成的任務分配給若干個單元電路，并畫出一個能表示各單元功能的整機原理框圖　　方案選擇的重要任務是根據(jù)掌握的知識和資料，針對系統(tǒng)提出的任務，要求和條件，完成系統(tǒng)的功能設計。而且，不僅單元電路本身要設計合理，各單元電路間也要互相配合，注意各部分的輸入信號，輸出信號和控制信號的關系。 電阻和電容的參數(shù)應選計算值附近的標稱值。例如選擇晶體三極管時，首先注意是選擇NPN型還是PNP型管，是高頻管還是低頻管，是大功率管還是小功率管，并注意管子的參數(shù) PCM ， ICM ， BVCEO ， ICBO ，β ，T和 β 是否滿足電路設計指標的要求?！　∮袝r一個總電路由幾部分組成，繪圖時應盡量把總電路圖畫在一張圖紙上。圖中，大規(guī)模器件外，其余元器件符號應當標準化。第一，使我們基本掌握了一項電子設計方面的技能,鞏固了我們所學的專業(yè)知識,培養(yǎng)了我們的創(chuàng)新素質(zhì)和鉆研精神。制作雖然在制作過程中，大家都盡心盡力，團結(jié)一致克服困難，但也還是遇到了不少的問題?！　≡O計的電路是否能滿足設計要求，還必須通過組裝，調(diào)試進行驗證。　　一般從輸入端和信號源畫起，由左至右或由上至下按信號的流向依次畫出各單元電路，而反饋通路的信號流向則與此相反。　　選擇的集成電路不僅要在功能和特性上實現(xiàn)設計方案，而且要滿足功耗，電壓，速度，價格等多方面的要求。設計時要根據(jù)電路的要求選擇性能和參數(shù)合適的阻容元件，并要注意功耗，容量，頻率和耐壓范圍是否滿足要求?！　?shù)計算時，同一個電路可能有幾組數(shù)據(jù)，注意選擇一組能完成電路設計要求的功能，在實踐中能真正可行的參數(shù)。三、 單元電路的設計，參數(shù)計算和期間選擇　　根據(jù)系統(tǒng)的指標和功能框圖，明確各部分任務，進行各單元電路的設計，參數(shù)計算和器件選擇。 (3) the parameter of electric resistance and electric capacity should choose a calculation value the mark of the neighborhood to call a value. 3. The spare part choose (1) the ponent choose The electric resistance and electric capacity category is much, electric resistance and electric capacity of the exactitude choice are very different electric circuit requests to be different also to the electric resistance and the electric capacity function and the electric leakage which has solution electric circuit to the electric capacity has very strict request, also some electric circuits are to the electric resistance, and function and capacity of electric capacity have very high example filter in mon use and big capacity(100 uF ～ 3000 uF) aluminum electrolysis electric capacity in an electric circuit, for filter out the high Pin usually still needs to merge small capacity( uF ～ uF) porcelain a slice electric permit a ponent according to choice function and the parameter suitable of the request of electric circuit while design, and want to notice an achievement to consume, capacity, frequency with bear to press whether scope satisfies a request or not. (2) the cent sign the choice of ponent Cent sign a ponent to include diode,triode,transistor, field effect tube, only give or get an electric shock two(three) poles tube etc..Carry on a choice respectively according to its use. 　 The period category of choice is different and the regulation is also example choice crystal triode transistor, first notice is to choose a NPN type or a PNP type tube, is Gao Pin2 Guan3 or a low frequency tube, is a big power tube or small power tube, and notice the parameter PCM, ICM, BVCEO, ICBO, β of pipe, whether T and β satisfies an electric circuit design the request of the index sign or not, high Pin work, request T=(5~10), is work frequency. (3) the integrated circuit choose Because the integrated circuit can carry out a lot of unit electric circuits the whole function of machine electric circuit even, so choose to design unit electric circuit with the integrated circuit convenient and vivid with total electric circuit, it not only make the system physical volume contract, and function credibility, easy to adjust to try and make use of, rather popular while designing electric circuit. The integrated circuit imitates integrated circuit and numerical integrated circuit home and abroad already the born be a great deal of integrated circuit, the model number, principle, function of its spare part, the characteristic can check concerning the manual. The integrated circuit of choice not only want to carry out a design a project on the function and the characteristic, and want to satisfy achievement consume, electric voltage, speed, price etc. various of request. Four. The electric circuit diagram draw In order to mean the whole machine electric circuit of the design and the conjunction of each unit electric circuit relation in detail, design need to draw plete electric circuit diagram. Electric circuit diagram usually is at system frame diagram, the design, parameter calculation and spare part of the unit electric circuit choose of foundation up draw of, it is a construction and adjust to try and maintain of notice once what time while drawing electric circuit diagram: