Some of us have used, played with or at least seen surplus WWII communication gear that used crystals like these:
and probably even more of us used more modern crystal controlled radios and scanners. The video below details the manufacture of WWII crystals by the Reeves Sound Laboratory under contract with the Signal Corps.
Modern crystals are (usually) smaller and the manufacturing process is more automated, but there's a lot of similarities. The video shows the multitude of steps needed to transform a pretty rock into a precise piezoelectric device. I also found it interesting, and a little horrifying, to see the safety precautions used by the workers in the video as compared to what modern OSHA standards would require.
You can watch the 30 minute video here: https://youtu.be/duZlWWwxIPQ
And for a little more detail on quartz crystals and their aging:
www.planetanalog.com
and probably even more of us used more modern crystal controlled radios and scanners. The video below details the manufacture of WWII crystals by the Reeves Sound Laboratory under contract with the Signal Corps.
Modern crystals are (usually) smaller and the manufacturing process is more automated, but there's a lot of similarities. The video shows the multitude of steps needed to transform a pretty rock into a precise piezoelectric device. I also found it interesting, and a little horrifying, to see the safety precautions used by the workers in the video as compared to what modern OSHA standards would require.
You can watch the 30 minute video here: https://youtu.be/duZlWWwxIPQ
And for a little more detail on quartz crystals and their aging:
A brief history of quartz crystals and their aging problem - Planet Analog
There is a complex tale of physics, geology, and production challenges behind quartz crystals and oscillators that traces back to World War II.
www.planetanalog.com
