Sunday, December 28, 2014

What's in an Inexpensive Centrifuge?

I've added a low-speed centrifuge to my lab equipment. It is a Chinese-made device sold on Amazon by Hardware Factory Store. It works well, I can recommend it if you need a basic centrifuge.



I was curious what was inside, what does $110 get you?


Looks like a 25W 110V universal motor and a NXP BT136-600E triac controller. The rotor is light aluminum sheet, and the motor is mounted with rubber isolators.

The control panel:


Has a speed control (top), power switch and indicator (middle) and a mechanical timer (bottom). Notice that this control panel is different from the external picture of the unit which uses an illuminated switch where this one has a separate light.

Details of the motor controller:



Just your basic triac controller.

I noticed that if I put 115mm centrifuge tubes into it the tub runs into something inside. I put a camera inside and closed the unit to see what the problem was:


Turns out that modified power indicator is in the way. I'll fix that by 3D printing some collars to hold the tubes up a little farther so that they clear the indicator.
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