Saturday, July 26, 2014

Ultra low-temperature cascade refrigeration system repair

I bought a -100*C refrigerated cold trap from a surplus sale, which was not operational.  In this video, I describe how the unit works after recharging its second stage with R1150 (ethylene) refrigerant.

Savant RVT4104 - (manual)

Wednesday, July 16, 2014

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Monday, July 7, 2014

How to electropolish aluminum

I show a basic electropolishing technique that requires no special equipment and has proven to work well on aluminum (aluminium).

Sunday, June 29, 2014

Mathematical integration without calculus

I show how to convert an area measurement problem into a mass measurement problem that is easier to solve.  In general, this idea of converting measurement problems into different spaces is very powerful, and may prove useful in the future.

Sunday, June 8, 2014

Measure the mass of an eyelash with a DIY microbalance

I built a microbalance based on a design by Paul Grohe:

It is has a precision of about 5 micrograms, and I measured a single eyelash at about 35 micrograms.  The balance is built from an analog panel meter that is controlled by a servo loop which optically monitors the meter's position. Adding mass to the meter's needle requires that the servo loop add more current to maintain the needle's position.  This additional current is read, and converted to a mass value.