用馬鈴薯判斷電極的正負...

Hacker News Daily 上看到「“You don't have a voltmeter. Do you have a potato?” (diy.stackexchange.com)」這則討論,原討論在「Is white wire with grey stripes positive or negative wire?」這邊,有人問了一個問題,說手上有一個交流轉直流的變壓器,想要重新接線到下面這種端子,但不確定變壓器輸出的兩條線裡面,正極與負極分別是哪條:

下面的答案很厲害啊,開頭先說如果你沒有伏特計 (像是三用電錶),那手上有沒有馬鈴薯:

You don't have a voltmeter. Do you have a potato?

把馬鈴薯切半,把 DC 端的兩條線插到同一顆馬鈴薯上面,大約相距 2cm,插電不久後就可以看到有一端會變綠,那端就是正極,把本來插到馬鈴薯上的端子剪掉後再接線就可以了:

With the power adapter unplugged from your electrical outlet, cut the wires, strip a little insulation from the ends, twist the strands of each wire into a point. Do not allow the bare wires to touch each other from this point on.

Cut the potato in half. Take one half, and poke both wires into the cut face of the potato about 2 cm apart. Plug in the power adapter to the wall outlet. In a short time, the potato around one of the wires will turn green. That is the positive wire.

Unplug the adapter and clip off the ends of the wires so you have clean wire for soldering your new plug.

不確定產生的是不是銅綠,但能給出這種解法的確很有娛樂性 XDDD

國際太空站要裝咖啡機了...

在「The International Space Station (Finally) Gets an Espresso Machine」這篇看到的,原始的報導出自「The International Space Station (finally!) gets an espresso machine」。

幾個重點 XDDD

The ISSpresso requires 120V DC power which is obtained at the Utility Outlet Panel (UOP) on the ISS.

很特別的電力,是 120V DC 而非 120V AC...

筆記型電腦的充電器單一化...

Slashdot 上看到「Standardized Laptop Charger Approved By IEC」這篇。

2011 年年初的「歐盟強制使用 Micro USB 做為手機充電介面」後,IEC 這次宣佈要標準化筆電的充電器:「Major milestone: single charger for notebook computers will significantly reduce e-waste」。

目前的進度在最後一段可以看到:

IEC Technical Specification 62700: DC Power supply for notebook computer, will be available in early 2014.

不過... 筆電充電器這塊如果要做的好用,不會卡到蘋果的專利嗎?

直流電電源供應 PC...

Slashdot 上看到英國有大學嘗試使用直流電供應電腦電源:「University Switches To DC Workstations」。

在機房內有些設備是可以吃 48V DC,也有 UPS 是設計給 48V DC 用的 (APC AV Black S Type Extended Battery Pack 48Vdc),當初聽別人說是「因為轉換效率比較高所以省電」,但究竟可以省多少?我記得現在的 110V/220V 的 AC ATX PSU 轉換效率超過 80%?機房端轉成 110V/220V AC 與 48V DC 又差多少?

試著找 48V DC ATX PSU,有找到「48 V DC Input PC ATX-12 Style Power Supplies」這個,另外也有其他電壓的 PSU...

感覺一般電腦用 DC Input 是一種新的嘗試,也是 PR 稿...