On 6/6/2012 7:14 AM, Geoffrey Voeth wrote:
> Hello PSN;
>
> I just uploaded to my site the final version of
> the program which will be used to build my
> next antialize filter.
>
> I don't use version numbers I use date of Compilation
> to follow my programs.
>
> I do not sell anything.
>
> It is only for a hobby I do these things.
>
> PSN is only a fraction of my time/life on the internet.
>
> But it is one of the more fun things I do.
>
> Input Fo in Hertz and a single C value in Farads and it will
> produce a text file with recommended
> component values for N=2,4,6,8 LPF Butter-worth
> I think the filter type to be Sallen-Key.
>
> The formulas can be found in the ARRL
> Handbook 2004 in section 16.
>
> The idea was tested in the LTSWCAD IV software
>
> I use a OP177GPZ op amp for this test.
>
> I am currently using a similar design
> the past few years without problems.
> But it is 10Hz and not the 2Hz i intend to try.
>
> This is not for use with Larry's Amp Boards
> it is intended for a straight through
> preamp with no other conditioning.
> I think you don't need this if using Larry's
> amplifiers.
>
> But, it will output to his 16bit Type III A/D converter nicely.
> Just make sure your supply voltages are suitable.
>
> About +/- 5.6V to 5.7V if on the 5V A/D setting
> may be like +/- 10.7 if using the 10V setting.
>
> This is for people who enjoy building their own stuff
> like the old heathkit times.
>
> The area I concentrate on is the cheapest link in the chain
> Which is the Preamp/Filter between the Geophone and the A/D Timer
> board. The other stuff requires too much money to build
> or at least thats the way i see it.
> It would be nice to build the Whole thing
> But Who Provides such a kit ??
> Only peoples with the right shop/tools can deal with these.
> A sensor with 10V/in/sec would certainly be nice.
>
> I have included the source code the Compiled x32 EXE code
> and graphic examples of what i will be trying to build.
>
> You can find the package for download at my home site
> bottom of the page.
>
> http://www(dot)amaseistagva(dot)com/index.html
> http://amaseistagva(dot)com/index.html
>
> To Download:
> 1. Navagate to bottom of page
> 2. Right Click the PAS file (for pasworded)
> 3. select (left click) [save target as... ] option
> 4. select your download area on your machine
> After Download
> 1. rename the RAR SFX file from .pas to .exe
> 2. run file
> 3. enter password: asisfreeware
> 4. rename extraction folder
> 5. run exe file within new folder
>
> The renaming has been done to try and avoid filtering of executable
> stuff around the internet.
>
> I expect you to have no troubles if running x32 or x64 windows.
>
> Let me know if you have any troubles running it.
> I may not be able to do anything about it
> it would just be nice to know.
>
> Now back to BF3, I like flying those helicopters.
> even tho I don't live very long.
>
> Regards,
> geoff
>
>
>
>
>
>
>
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>

I just constructed the N6 version of the antialize filter
for 2Hz and although it seems to function the freq is a bit low.
This means I need to tweak it a bit.
I allowed room for this by putting a 1K potentiometer
between R1 and R2 picking off from the wiper to the
feedback capacitor.

Does anyone know the best way to inject a white noise
into the front end (where the geophone connects) to
see a proper frequency profile through the system ?

I would use either Winquake or Audacity to look at the resulting spectrum.

Like, what a simple way to create a low frequency
white noise generator ? (if you know what i mean ??)

geoff

NOTE on my software, it is built just to help in
finding the right values not to be user friendly.
I generally recompile the program repeatedly
changing things to suit my needs.
It will never be the same for all time
unless I finalize things.

NOTE I just learned to hard boil an egg in the microwave
while waiting for the Earthquakes, Here's how it goes :
My altitude is at a boiling point of about 207F
1. put 10Oz avdp. H20 into 16oz styro cup.
2. Wrap egg 100% in one layer of Al Foil.
3. put foil wrapped egg into cup of water
4. put all into uwave at full power for three minutes
5. reduce power to around between 40% to 30%
6. turn on uwave to maintain temp of 200F (just under the boil point) 
for 5 minutes
7. let cool to 140F then its ready to peel sprinkle with salt and devour.

Its the faraday shielding which keeps the egg from exploding.
The hot water cooks it and not the uwaves.

This lets you cook one egg at a time instead of a dozen.
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