This liquid nitrogen generator uses a Stirling-cycle cryocooler that was pulled from a cellular phone tower. It was used to cool a superconducting RF filter that aids cell communications. The cryocooler is able to pump enough heat away from its cold end that air will liquify and drip into a vacuum flask for storage.

Jeri's video at Maker Faire 2010:    • DIY Liquid Nitrogen for Less Than $50...  


Blog post with more construction details: http://benkrasnow.blogspot.com/2008/0...