若你是一名電子工程師,有些數字會讓你刻骨銘心,比如4004(世界上首款商用微處理器晶片)和8051(如果不是首款,那肯定是早期微控制器中最受歡迎之一)。
vnIednc當然,還有一個讓我們所有人都戀戀不忘的數字,那就是555。它是Signetics定時器集成電路(IC)命名所採用的數字,由Hans R. Camenzind於1971年設計並於1972年上市。它包括25個電晶體、兩個二極體和15個電阻器,並利用到了一些巧妙的設計技術,例如用直接內部電阻來代替外部恆流源——Hans設法將此555塞入到8引腳的封裝中。
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第一代Signetics NE555(來源:Stefan506)
vnIednc555有三種主要工作模式:單穩態(單次觸發)、雙穩態(施密特觸發器)和無穩態(自激振蕩)。555的多功能性,加上其低廉的價格、易用性和穩定性,使得很多人至今仍在使用它。多年來,電子愛好者和專業工程師們已經用這個「小滑頭」開發了成千上萬的應用。
vnIednc我們中有許多人都對555有著濃厚的感情,其中有些人又比其他人更感興趣。例如,我的朋友Daniel B. Levine(danielblevine.com)——EEWeb上「Raster Scam: An Unconventional History of Computer Graphics」一文的作者——就給我發了以下這首詩:
vnIedncOde to a 555 Timer (by Daniel B. Levine) (求大神翻譯!)Thou still unravish』d bride of analog design,vnIednc
Thou foster-child of biplanar process and time,vnIednc
Neither engineer nor poet escapes the seductionvnIednc
Of the perfection of your monolithic construction.vnIednc
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You quicken the pulse, our composure you savagevnIednc
When our gaze falls upon your eight-pin, dual inline package.vnIednc
Or a milspec』d can, for space, sea or air,vnIednc
Or the romantic 556—entwined as a loving pair.vnIednc
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Triple six may well be the mark of the beast,vnIednc
But the angels beamed when the triple five was released.vnIednc
You discharge to the world a positive supplyvnIednc
Of square waves as your output toggles twixt low and high.vnIednc
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Your fame unsurpassed, your reputation a tower,vnIednc
There’s even a CMOS version for circuits with low power.vnIednc
Though in this configuration noise is a struggle,vnIednc
So always include a capacitor to decouple.vnIednc
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You switch without bounce, dividing a frequency,vnIednc
Or modulating a pulse, all monostable-ly.vnIednc
You compare with hysteresis, ignoring any hater vnIednc
Jealous of your bistable multivibrator.vnIednc
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Your duty cycle’s variable, your comparator’s exacting,vnIednc
Who knew astable oscillation could be so relaxing?vnIednc
With every trigger we reset our faith anew,vnIednc
And though you may flip-flop, we forever stay true.vnIednc
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You’re in every expert’s kit, and every student’s primer,vnIednc
You stand, without peer, as the world’s favorite timer.vnIednc
So say we all as long as engineering remains alive,vnIednc
I think that I shall never spy a poem as lovely as a 555.
我必須承認這首詩給我帶來了樂趣。它還讓我想起了Evil Mad Scientist網站上的The Three Fives Kit(555套件)。
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555套件(來源:evilmadscientist.com)
vnIednc這款套件極具美感,是採用分立電晶體和電阻器搭建的經典NE555定時器的功能性複製品(左下角顯示了真實的555晶片用於比較)。
vnIednc這款555定價為35美元,它配備了接線柱,用戶可以連接它,用它來構建基於555的經典定時器和振蕩器電路(網上提供有大量此類電路,如:《50個555電路集錦》https://forum.mianbaoban.cn/topic/65468_1_1.html)。vnIednc
由此我也產生了一個想法。猜猜看我在想什麼?vnIednc
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