Fonte Simetrica

Fonte Simetrica
http://blog.novaeletronica.com.br/en/o-que-e-uma-fonte-simetrica/
https://www.youtube.com/watch?v=VVaYrS3o2ws
http://www.learningaboutelectronics.com/Articles/Shift-register-circuit.php
http://www.learningaboutelectronics.com/Projects/
http://www.learnerswings.com/2014/07/5v-0-5v-voltage-regulator-using-7805.html
http://www.learnerswings.com/2014/07/79xx-series-three-terminal-voltage.html