60 Hz Twin-T Notch Filter

[epitopios]

The twin-T notch is built from old-fashioned mica capacitors and inserted into a small plastic box (simply for convenience). Any capacitor type will work as long as the values are precise. Two, 270 k resistors are placed in series to achieve 540 k and two, 0.005 uF capacitors are paralleled to achieve 10 nF so only one value of each type part is needed. The bridging resistor, about 1 megohm, that lets a little hum pass this filter is located on the protoboard and is not shown in the schematic. The dedicated protoboard is beginning to earn its keep!



friendly epitopios

[epitopios]

calculate

also if you want to
Design an L-C Low pass or High pass Filter go to :
http://www.wa4dsy.net/filter/hp_lp_filter.html

also:
Lowpass and Highpass Filter Calculator:

http://www.wa4dsy.net/robot/active-filter-calc

Bandpass Filter Calculator:

http://www.wa4dsy.net/robot/bandpass-filter-calc

Resonant Frequency Calculator

http://www.wa4dsy.net/filter/fr.html

Design a custom Interdigital Bandpass Filter:

http://www.wa4dsy.net/cgi-bin/idbpf



WinFilter The easiest way to design a Digital Filter:

http://www.winfilter.20m.com/


IIR explorer is a small Windows app to explore digital filters in an intuitive way: move poles and zeros on the complex plane and see in real time how this affects the magnitude and phase response of the filter:
http://www.terdina.net/iir/iir_explorer.html

Filter A program to design digital filters:
http://easyweb.easynet.co.uk/~nbarnes/Shareware.htm

FilterCAD (FREE):
http://www.linear.com/designtools/software/#Filter

eSeptum Waveguide Filter Design Program(demo) :


http://www.engineers.com/eseptum.htm

Welcome to Filter Solutions Filter Light and Filter Free! :
http://www.nuhertz.com/filter/

Elsie™ is an uncommon commercial-grade lumped-element ("L-C") electrical filter design and network analysis program, directed toward the engineer or technician involved in that line of work.
http://tonnesoftware.com/elsie.html

Helical This is a graphics-intensive bandpass filter design and analysis program based on the helical resonator.
http://tonnesoftware.com/helical.html

and more at:
http://www.circuitsage.com/filter.html

I found all those stuff interesting for your PC library

friendly, epitopios