Thanks for the answers.

Nice to know there are different methods for this..

Im using the geophone connected directly to the ADC in a breadboard at
~22bits, so i have noise in it.. also i=C2=B4m limited to the 16bits from
AmaSeis, so some spikes are only displayed up to 16bits.

 The geophone looks like its responding quite well at 10Hz, i did tried
tapping with a pencil or different objects to create some "spikes", but
didint reach any good result. I did not managed to get any good recording
lower than 5Hz..

Here is the *.sac file with some tests (small/fast taps on the floor, in a
table, etc etc). The sample rate is at 125SPS, which give a -3dB filter at
~33Hz.
http://dl.dropbox.com/u/15802004/testing.sac

Is it possible anyone see the results and if some movement clearly shows
the natural frequency of the geophone, tell me the time in the recording?

Thanks.

2012/4/16 GeoffG 

> On 4/16/2012 7:04 AM, Mauro Mariotti wrote:
>
>> Hi,
>>
>>
> I would hook up the geophone to the WINSDR program
> with no damping then excite it somehow then
> convert the PSN file to a wave file and examine
> the spectrum in the Audacity program.
> It can show you an FFT Waterfall display
> and is free for personal use if you
> are not making money at what you do.
> But also the FFT within WinQuake can also
> show you the spike at F0.
> Resonance.
>
>
>
>
>  also better is to bias the coil with a small battery.
>> A simple AA battery (also one with just a residual of charge).
>> Connect an oscilloscope or other suitable device to the sensor output.
>> Atthe same time connect the battery - to ground of oscilloscope and the
>> use the + of battery to excite the geophone.
>> Do this all with the geophone in its natural position (horizontal if it
>> is horizontal sensitivity, or vertical if it is a vertical sensitivity
>> one).
>> You will see a nice swing when you release the + bias from the sensor.
>> The time between of the top of two sequential wave crest tell you the
>> period, and its reciprocal is the freqency.
>>
>> best regards
>> Mauro
>>
>> Il 16/04/2012 02:23, Tiago Agrelos ha scritto:
>>
>>> Hi.
>>>
>>> I=E6=89=89e small geophone almost a year, but i never knew its natural
>>> frequency, how can i "find" its approximate natural frequency?
>>>
>>> The geophone doesnt have anything written on it, its smaller than 4.5Hz
>>> L15B geophone sold by Larry, generate a lot more output than the 4.5Hz
>>> one and i read 380ohm from it.
>>>
>>> I appreciate any help.
>>>
>>> Regards,
>>> Tiago.
>>>
>>
>>
> ______________________________**____________________________
>
> Public Seismic Network Mailing List (PSNLIST)
>
> To leave this list email PSNLIST-REQUEST@.............. with the body of
> the message (first line only): unsubscribe
> See http://www.seismicnet.com/**maillist.htmlfor more information.
>
Thanks for the answers.

Nice to know there are different methods for=
 this.. 

Im using the geophone connected directly to the ADC in a br=
eadboard at ~22bits, so i have noise in it.. also i=C2=B4m limited to the 1=
6bits from AmaSeis, so some spikes are only displayed up to 16bits.


=C2=A0The geophone looks like its responding quite well at 10Hz, i did =
tried tapping with a pencil or different objects to create some "spike=
s", but didint reach any good result. I did not managed to get any goo=
d recording lower than 5Hz..


Here is the *.sac file with some tests (small/fast taps on the floor, i=
n a table, etc etc). The sample rate is at 125SPS, which give a -3dB filter=
 at ~33Hz.
http=
://dl.dropbox.com/u/15802004/testing.sac


Is it possible anyone see the results and if some movement clearly show=
s the natural frequency of the geophone, tell me the time in the recording?=


Thanks.

2012/4/16 GeoffG <gmvoeth@.........>=
;

On 4/16/2012 7:04 AM, Mauro Mariotti wrote:<=
br>

Hi,






I would hook up the geophone to the WINSDR program

with no damping then excite it somehow then

convert the PSN file to a wave file and examine

the spectrum in the Audacity program.

It can show you an FFT Waterfall display

and is free for personal use if you

are not making money at what you do.

But also the FFT within WinQuake can also

show you the spike at F0.

Resonance.









also better is to bias the coil with a small battery.

A simple AA battery (also one with just a residual of charge).

Connect an oscilloscope or other suitable device to the sensor output.

Atthe same time connect the battery - to ground of oscilloscope and the

use the + of battery to excite the geophone.

Do this all with the geophone in its natural position (horizontal if it

is horizontal sensitivity, or vertical if it is a vertical sensitivity

one).

You will see a nice swing when you release the + bias from the sensor.

The time between of the top of two sequential wave crest tell you the

period, and its reciprocal is the freqency.



best regards

Mauro



Il 16/04/2012 02:23, Tiago Agrelos ha scritto:


Hi.



I=E6=89=89e small geophone almost a year, but i never knew its natural

frequency, how can i "find" its approximate natural frequency?


The geophone doesnt have anything written on it, its smaller than 4.5Hz

L15B geophone sold by Larry, generate a lot more output than the 4.5Hz

one and i read 380ohm from it.



I appreciate any help.



Regards,

Tiago.







__________________________________________________________



Public Seismic Network Mailing List (PSNLIST)



To leave this list email PSNLIST-REQUEST@.............. with the body of the m=
essage (first line only): unsubscribe

See h=
ttp://www.seismicnet.com/maillist.html for more information.