Friday, November 29, 2019

DIY mass spectrometer measures potassium in dietary salt substitute

How to build and operate a simple mass spectrometer. Please ask questions in the comments, as always.

Scientific American article:  $7.99 is a good value for the entire back issue in plain PDF format, and an example of a publisher being reasonable.   I'm happy to support this.

Original Dewdney paper:

Friday, October 11, 2019

Teardown of a "date back" or "data back" camera and description of how it works: A micro LCD projector with incandescent light bulb!

Tuesday, September 3, 2019

Cryogenic treatment of drill bits: tested 2X lifetime and microstructure analysis

I bought some HSS stub drills, and treated half of them with liquid nitrogen, which improved their wear resistance dramatically. I also look at the change in microstructure with an electron microscope.

Performance of cryogenically treated M35 HSS drills -
Performance of cryogenically treated HSS tools -
Effects of Cryogenic Treatment on the Strength
Properties -

LN2 generator video:
Heat treatment of steel video:

Source of drill bits:

Temperature logger (discontinued, unfortunately):

3M fine polishing pads:

Delorean patent on cryogenic torsion bar:

Steel grain structure inspection, and overall great channel for material analysis:

Steel grain structure video:

Applied Science on Patreon:

Monday, August 5, 2019

UV laser creates disappearing ink in normal printer paper

Ordinary printer paper is darkened by a high power UV laser, and then the affected area disappears in four minutes!  This is caused by fluorescent brightening agents that are added to printer paper, which are temporarily overloaded by the intense UV light. It seems that oxygen plays a role in this, as hydrogen peroxide applied to the marks cause them to disappear instantly, and prevent them from being formed again by the laser. Performing the experiment in argon appears to slow the disappearing ink effect.

Wednesday, July 3, 2019

"Bouncy" sulfur hexafluoride gas in tennis balls?

Testing myths about gas inside tennis balls.
Note:  I should have added that all of the gases tested would have the same bounce height in a perfect no-loss system.  The reason that SF6 bounces higher is because it heats less during compression, lowering the amount of possible thermal loss.  Argon heats more during compression, and can lose more energy because of thermal transfer from the gas into the cylinder walls, where it is not restored upon decompression.  Things are more complex in a tennis ball, though:  Most of the losses are in the rubber shell, and not in the thermal dissipation of the fill gas.  It's hard to estimate, but I'd say that the highest fill pressure, with a high-gamma gas would prove to be the most bouncy since it would cause the rubber shell to deform the least.  The amount of compression in a tennis ball is very low, and any effect due to the gamma of the gas will be extremely small.  Fill pressure will have a dramatically bigger effect.

Google drive link :
 Nike Air:

EPA SF6 use:

100 kg load cell:
Instrumentation amplifier:

SF6 on eBay:

Tennis ball patent:

SF6 data sheet:

SF6 worldwide usage:

General adiabatic resources: