I need a little math help now
metron9
Posts: 1,100
I have gone back to an older project spured on by another question from a poster on these boards.
This link shows a bandpass circuit, i connected it up and tested it and it works great. It gives the formulas to calculate the resistors and I would like to put it into a spreadsheet so I can build a dozen of them to run a·LED equalizer wall display using 12 - 4 foot bars of LED's to make a digital wall mounted equalizer·but I don't fully understand what some of the variables are. (note I saw a book today by Trump that said think BIG so I am giving that a try on a small scale)
For example to calculate R1
R1 = Q / (G*C*2*Pi*F) = 8/(65 * .00000001 * 6.28 * 1700) = 1152 or 1.1K
Dont know what G is and wether C is equal to the formula shown above this one (on the link)
Center Frequency = Square Root of (Lower Frequency * Upper Frequency)
Also F i think would be frequency but if C=center frequency then what is F?
R2 and R3 calculations are
R2 = Q / ((2*Q^2)-G)*C*2*Pi*F) = 8/((128-65) * .00000001 * 6.28 * 1700) = 1189 or 1.2K
R3 = (2*Q) / (C*2*Pi*F) = 16 / (.00000001 * 6.28 * 1700) = 150K
http://www.circuitdb.com/circuits/id/162
If someone could help me with that I could then continue the project.
Ahh gees, one trip to the bathroom and I think i came up with the answer to C and F,·C=capacitor·and F=Center frequency
Still don't see what G is though.
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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Post Edited (metron9) : 11/5/2007 4:51:30 AM GMT
This link shows a bandpass circuit, i connected it up and tested it and it works great. It gives the formulas to calculate the resistors and I would like to put it into a spreadsheet so I can build a dozen of them to run a·LED equalizer wall display using 12 - 4 foot bars of LED's to make a digital wall mounted equalizer·but I don't fully understand what some of the variables are. (note I saw a book today by Trump that said think BIG so I am giving that a try on a small scale)
For example to calculate R1
R1 = Q / (G*C*2*Pi*F) = 8/(65 * .00000001 * 6.28 * 1700) = 1152 or 1.1K
Dont know what G is and wether C is equal to the formula shown above this one (on the link)
Center Frequency = Square Root of (Lower Frequency * Upper Frequency)
Also F i think would be frequency but if C=center frequency then what is F?
R2 and R3 calculations are
R2 = Q / ((2*Q^2)-G)*C*2*Pi*F) = 8/((128-65) * .00000001 * 6.28 * 1700) = 1189 or 1.2K
R3 = (2*Q) / (C*2*Pi*F) = 16 / (.00000001 * 6.28 * 1700) = 150K
http://www.circuitdb.com/circuits/id/162
If someone could help me with that I could then continue the project.
Ahh gees, one trip to the bathroom and I think i came up with the answer to C and F,·C=capacitor·and F=Center frequency
Still don't see what G is though.
·
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!
Post Edited (metron9) : 11/5/2007 4:51:30 AM GMT
Comments
There is a nice application note, "Filter Design in 30 Seconds", search for SLOA093 on the Texas Instruments web site.
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Tracy Allen
www.emesystems.com