Zero crossing detector
From emboxit
- http://www.ijera.com/papers/Vol3_issue5/ES35834838.pdf
- http://tesla.zabotavdome.ru/zero/zc.pdf
- https://www.elprocus.com/zero-crossing-detector-circuit-and-working/
- http://sound.whsites.net/appnotes/an005.htm
- http://cds.linear.com/docs/en/application-note/an72f.pdf
- http://www.linear.com/solutions/5291
- http://cds.linear.com/docs/en/datasheet/1116fc.pdf
- http://www.mouser.ie/ProductDetail/Texas-Instruments/TL3116CD/?qs=%2fha2pyFaduhxtP7mJZTym5WQCRAKINO28n%252bI6lyI%2fbcmY3Hus25gDg%3d%3d
- http://www.ti.com/lit/ds/symlink/tl3116.pdf
