If you have a digitizer suitable for seismic recording, I recommend impulse
response testing. If you FFT analyze the recorded response of your
amplifier/filter to an impulse, the spectral response plot will be the
answer. You can generate the impulse by connecting a charged capacitor to
the input of the amplifier. You must ascertain that the spike does not
overload the amplifier, and you must ensure that the R-C time constant is
short enough to accommodate the highest frequency passed by your
amplifier/filter. Your sampling rate should also be more than twice the
maximum passband frequency.

Bob

On Sun, Dec 5, 2010 at 3:06 PM, Richard Schneider  wrote=
:

> Hello PSN,
>
>
>
> I would like to run a frequency response test of my amplifier/filter but =
I
> only have test equipment in the 50 Hz to 50 KHz range.
>
>
>
> Do any of you have a recommendation for constructing a generator that wou=
ld
> output DC to 5 Hz with a uniform (flat response) voltage?
>
>
>
> There was a CD disc someone was selling (RefCD) at the URL below that
> modulates a 1 KHz sine wave with a 1 Hz since wave. I believe the idea is=
 to
> filter out the 1 KHz signal at the output of a PC sound card. What are le=
ft
> are pure VLF signals that could be used to sweep the amplifier/filter.
>
>
>
>
> http://www.science-project.com/_members/science-projects/sponsorads/refcd=
/seis.html
>
>
>
> I know there are several freeware tone generators you can download, but I
> don=92t think a PC sound card can reproduce DC to 1 Hz. Am I correct?
>
>
>
> Thank you,
>
>
>
> Rich
>
>
>
If you have a digi=
tizer suitable for seismic recording, I recommend impulse response testing.=
 If you FFT analyze the recorded response of your amplifier/filter to an im=
pulse, the spectral response plot will be the answer. You can generate the =
impulse by connecting a charged capacitor to the input of the amplifier. Yo=
u must ascertain that the spike does not overload the amplifier, and you mu=
st ensure that the R-C time constant is short enough to accommodate the hig=
hest frequency passed by your amplifier/filter. Your sampling rate should a=
lso be more than twice the maximum passband frequency.



Bob

On Sun, Dec 5, 2010=
 at 3:06 PM, Richard Schneider <cfi2fly@.........> wrote:


Hello PSN,
=A0
I would like to run a frequency response t=
est of my amplifier/filter but I only have test equipment in the 50 Hz to 5=
0 KHz range.



=A0
Do any of you have a recommendation for co=
nstructing a generator that would output DC to 5 Hz with a uniform (flat re=
sponse) voltage?



=A0
There was a CD disc someone was selling (R=
efCD) at the URL below that modulates a 1 KHz sine wave with a 1 Hz since w=
ave. I believe the idea is to filter out the 1 KHz signal at the output of =
a PC sound card. What are left are pure VLF signals that could be used to s=
weep the amplifier/filter.



=A0
http://www.science-project.com/_members/science-projects/spo=
nsorads/refcd/seis.html



=A0
I know there are several freeware tone gen=
erators you can download, but I don=92t think a PC sound card can reproduce=
 DC to 1 Hz. Am I correct?



=A0
Thank you,
=A0
Rich
=A0