Author: Carl

I have aways sort of vaguely assumed that at some point in my youth I must have sat in a class in which the teacher made a potato battery and used it to light up a light bulb.  Recently I got it into my head that it might be interesting to reconstruct that old classroom demonstration.  But events of the past few days, recounted in this blog article, make me think that the old classroom demonstration must have never actually happened.  I must have just read about it in books and I must have sort of assumed that you could do, in real life, anything that is described in a book.  After many false starts, I did eventually manage to light up a light with a potato battery.  Continue reading “quantum physics and potato batteries”

Loyal readers will recall that recently I did a large number of test welds to measure welding currents generated by my new inexpensive stick welder (blog article).  I had been using my smart phone to log real-time current measurements via Bluetooth from a clamp-on DC ammeter (blog article).  Part way through the large number of test welds, I was astonished to see that my smart phone had powered itself down.  I tapped the power button and coaxed the phone back to life and completed my current logging activities, and eventually figured out why the phone had so mysteriously and abruptly powered itself off.  A tiny bit of hot steel from one of my test welds had flown several feet and had landed on the glass screen of the phone, and had melted a small crater in the glass.  You can see the crater, which is less than one-fourth of a millimeter in diameter, in the photomicrograph above.  After about a day, cracks had traveled from this crater across the full expanse of the glass.  I realized I would need to learn how to replace the screen.  This blog article describes it.  Continue reading “Replacing a screen of a smart phone”