밴드패스필터
http://www.electronics-tutorials.ws/filter/filter_4.html

Low Pass Filter 로우패스필터
http://www.electronics-tutorials.ws/filter/filter_6.html

Hihi Pass Filter 하이패스필터
http://www.electronics-tutorials.ws/filter/filter_3.html

Band Pass Filter 밴드패스필터

http://www.electronics-tutorials.ws/filter/filter_4.html

RC Charging Circuit
http://www.electronics-tutorials.ws/rc/rc_1.html

http://phy415.ahepl.org/html/chp2__rlc_circuits.html