from Hacker News

Borax or Baking Soda Rectifier and the glow (2003)

by _spduchamp on 12/11/24, 2:34 AM with 15 comments

• by stevetron on 12/12/24, 2:48 AM

  When I was in 9th-grade jhs, I performed a similar experiment in my science class. Nobody had a clue back then (1968) of what 'borax' was or where to get it. I substituted boraxo hand soap. For the experiment to work, it took a huge amount. I didn't use an oscilloscope back in that day. I remember rigging some kind of polarity detector using an incandescent lamp (probably a #222), and a couple of cheap silicon diodes from Radio Shack. For electrodes, which were inteneded as lead and aluminum, I used some sheet aluminum my dad kept around for some of his projects, and for the lead, I used a length of 50% lead 50% tin solid wire (no flux core) plumbing solder. I used a pint-sized mason jar, a mason ring, and cut a top for the jar from some thin cork I had. I may have used some cheap binding posts to suspenmd the electrodes from. I made the test right after lunch, say 1:00pm, and proved rectification with a 10-volt drop through the rectifier. After school, say 3:00 pm, the schools Science club, of which I was a memeber, convened in that room for a regular meeting. I attempted top repeat the experiment, and it failed: my rectifier wouldn't conduct anything in any direction. The Boraxo seemed to have 'gelled' in the jar and had turned pink. I ended up disposing of all the 'mess'. I never repeated the experiment.

• by tmm on 12/12/24, 12:30 AM

  > This opens up another very fasciniting [sic] possibility. A cell with two adjustable aluminum plates (a variable capacitor) might very well be useable as an efficient light dimmer.

  This is how early stage lights were dimmed. See https://youtu.be/wRMEAYYW0dc

• by HeyLaughingBoy on 12/11/24, 9:25 PM

  > This is a circuit connected directly to the power mains. Use proper precautions.

  Ahhh. The sound of freedom!

• by somat on 12/12/24, 12:02 AM

  "I have observed an interesting N type negative resistance effect that happens only when the tip of a very sharp aluminum electrode is just barely touching the top surface of the solution."

  What exactly does negative resistance mean in this context? Based on the curve shown I would guess as the voltage increases past a point the resistance decreases. But it is fun to imagine this guy has discovered perpetual energy.

  update: of course there is a wikipedia page. https://en.wikipedia.org/wiki/Negative_resistance

• by tdeck on 12/11/24, 9:02 PM

  This site is full of great experiments and well worth checking out. I'm so glad to see it's still online:

  http://www.sparkbangbuzz.com/

• by fuzzfactor on 12/12/24, 5:27 PM

  Liquid-state electronic devices, including electrolyte.

  Not like solid-state silicon crystals and stuff.

  Also not completely incapable of doing some of the same things.

  It's light-emitting, it's a diode, it's an LED :)