Low frequency signal generator

  • Thread starter Dirk Bruere at Neopax
  • Start date
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Dirk Bruere at Neopax

Guest
Hi

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
Spehro Pefhany wrote:

On Tue, 26 Jul 2005 19:02:21 +0100, the renowned Dirk Bruere at Neopax
dirk@neopax.com> wrote:


Hi

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?


That's well within the range practical for direct synthesis with a
microcontroller. Well, depending on how good a sine wave you need.
Click to expand...
Thanks.
Since it will be feeding an inductive load it doesn't have to be too good.
However, I was hoping for some super chip with some switches as inputs, a sine
o/p and which drives a 4 digit LCD...

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
Dirk Bruere at Neopax <dirk@neopax.com> wrote in
news:3knc5aFt78qvU1@individual.net:

Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with
resolution around 0.01Hz Any ideas for a cheap solution?
Click to expand...
This is very easy with our dspstak boards. You could also do this with our
DSP-8300 modules. We have an article that discusses the method and also a
working set of examples.

http://www.danvillesignal.com/index.php?id=applications_signalgeneration

The modules are $125 in 100 qty. A dev kit is available for $250.

--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com
 
On Tue, 26 Jul 2005 19:02:21 +0100, the renowned Dirk Bruere at Neopax
<dirk@neopax.com> wrote:

Hi

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?
Click to expand...
That's well within the range practical for direct synthesis with a
microcontroller. Well, depending on how good a sine wave you need.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Dirk Bruere at Neopax wrote:

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?

Since it will be feeding an inductive load it doesn't have to be too good.
However, I was hoping for some super chip with some switches as inputs,
a sine o/p and which drives a 4 digit LCD...
Click to expand...
How's this for a super chip that does what you describe?

http://www.basicx.com/
http://www.basicx.com/Products/BX-24/bx24overview.htm
http://www.basicx.com/Products/BX-24/bx24specs.htm
http://www.basicx.com/appnotes/bx-24appnotes.htm
http://www.basicx.com/Products/SLCD/2X16LCDoverview.htm
 
Try the Maxim MAX038 IC. It generates sine, triangle, square, pulse
waveforms from 0.1Hz to 20MHz.

Jon
 
On 26 Jul 2005 13:03:25 -0700, "Jon" <jon.lark@l-3com.com> wrote:

Try the Maxim MAX038 IC. It generates sine, triangle, square, pulse
waveforms from 0.1Hz to 20MHz.
Click to expand...
The OP wants "resolution" of 0.01Hz, which for 1 Hz to 100 Hz would
require a 10-turn pot (and a VERY accurate dial), voltage regulation
and probably temperature compensation as well.
Actually I'm not sure what the OP wants, but if the stated
resolution is an indication of the accuracy he wants, it surely will
take a digital (microcontroller) solution most likely involving an
implementation of the "phase accumulator" concept.

Jon
Click to expand...
-----
http://www.mindspring.com/~benbradley
 
On Tue, 26 Jul 2005 19:02:21 +0100, Dirk Bruere at Neopax
<dirk@neopax.com> wrote:

Hi

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?
Click to expand...
Analog Devices serial DDS chip, maybe, if you don't mind some
programming to control it.

John
 
You might try a four pole switched capacitor filter chip like the
National MF-10. You put in a square wave of the fundamental frequency
and a sample clock of say 64 time higher frequency. You filter out all
(most) of the the harmonics and get out a sine wave .

Dick Hagerman
 
You might try a four pole switched capacitor filter chip like the
National MF-10. You put in a square wave of the fundamental frequency
and a sample clock of say 64 time higher frequency. You filter out all
(most) of the the harmonics and get out a sine wave .

Dick Hagerman
 
In article <1122416172.983020.86690@g44g2000cwa.googlegroups.com>,
rehagerman@aol.com <rehagerman@aol.com> wrote:
You might try a four pole switched capacitor filter chip like the
National MF-10. You put in a square wave of the fundamental frequency
and a sample clock of say 64 time higher frequency. You filter out all
(most) of the the harmonics and get out a sine wave .
Click to expand...
If you don;t need an exact frequency on the output, you can build an
oscillator with the switched cap filter acting as the frequency
determining components. This removes the need for the extra dividers at
the cost of an added dual diode and a couple of resistors.

Wire up both sections as band pass filters


Connect section #2's input to the BP output of section #1.

Take the HP output of section #2, run it through a simple diode limiter
and use it as the input to the section #1 filter.


--
--
kensmith@rahul.net forging knowledge
 
Dirk Bruere at Neopax wrote:

Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with resolution
around 0.01Hz
Any ideas for a cheap solution?
Click to expand...
Thanks for all the suggestions guys, and I'll keep them in mind.
However, I have decided the best (ie cheapest and hassle free)method is to use a
program like Audacity on a PC to generate the signal I need to high precision. I
can then either output it directly from the soundcard or convert it to MP3 and
play it from a portable device.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
Dirk Bruere at Neopax wrote:
Dirk Bruere at Neopax wrote:

Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with
resolution around 0.01Hz
Any ideas for a cheap solution?

Thanks for all the suggestions guys, and I'll keep them in mind.
However, I have decided the best (ie cheapest and hassle free)method
is to use a program like Audacity on a PC to generate the signal I
need to high precision. I can then either output it directly from the
soundcard or convert it to MP3 and play it from a portable device.
Click to expand...
I was just checking out with my old copy of CEP what happens when you add a
1Hz and a 1.01Hz sinewave. nice beat frequency.
The question is if the soundcard can output 1Hz without attenuating it a
bit. You should at least increase the output capacitors, so the lower
frequency -3dB point is 0.1Hz or less.
--
ciao Ban
Bordighera, Italy
 
Ban wrote:
Dirk Bruere at Neopax wrote:

Dirk Bruere at Neopax wrote:


Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with
resolution around 0.01Hz
Any ideas for a cheap solution?

Thanks for all the suggestions guys, and I'll keep them in mind.
However, I have decided the best (ie cheapest and hassle free)method
is to use a program like Audacity on a PC to generate the signal I
need to high precision. I can then either output it directly from the
soundcard or convert it to MP3 and play it from a portable device.


I was just checking out with my old copy of CEP what happens when you add a
1Hz and a 1.01Hz sinewave. nice beat frequency.
The question is if the soundcard can output 1Hz without attenuating it a
bit. You should at least increase the output capacitors, so the lower
frequency -3dB point is 0.1Hz or less.
Click to expand...
Well, as far as I know Audacity can create a tone at a very precise frequency.
However, you are correct about playing very LF stuff.
One solution is to create a stereo track with one channel at f1 and the other at
f2 where f1>f2, feed these into a summing op-amp and follow by some simple
filtering to get f1-f2.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
On Tue, 26 Jul 2005 19:02:21 +0100, in sci.electronics.design Dirk
Bruere at Neopax <dirk@neopax.com> wrote:

Hi

Looking for a low frequency signal generator chip that can put out a sine wave
varying in frequency from around 1Hz to 100Hz with resolution around 0.01Hz
Any ideas for a cheap solution?
To solve the LF cutof problem with a normal soundcard, think FM.
Click to expand...
Modulate an audio carrier say at 10KC/S with the LF frequency
required. Stuff the output into a 4046 PLL as an FM detector


martin
 
On Wed, 27 Jul 2005 20:59:03 +0100, Dirk Bruere at Neopax
<dirk@neopax.com> wrote:

..as far as I know Audacity can create a tone at a very precise frequency...
Click to expand...
Unless you take some steps to calibrate to an external reference, the
generated tone can be no more accurate than the quartz crystal
timebase in your soundcard. And I have found these crystal
oscillators to be off by as much as 1%. That's not very precise. To
be fair, most soundcards are better than that. About .02%.


-Robert Scott
Ypsilanti, Michigan
 
Dirk Bruere at Neopax wrote:

Ban wrote:

Dirk Bruere at Neopax wrote:

Dirk Bruere at Neopax wrote:


Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with
resolution around 0.01Hz
Any ideas for a cheap solution?


Thanks for all the suggestions guys, and I'll keep them in mind.
However, I have decided the best (ie cheapest and hassle free)method
is to use a program like Audacity on a PC to generate the signal I
need to high precision. I can then either output it directly from the
soundcard or convert it to MP3 and play it from a portable device.



I was just checking out with my old copy of CEP what happens when you
add a 1Hz and a 1.01Hz sinewave. nice beat frequency.
The question is if the soundcard can output 1Hz without attenuating it
a bit. You should at least increase the output capacitors, so the
lower frequency -3dB point is 0.1Hz or less.


Well, as far as I know Audacity can create a tone at a very precise
frequency.
However, you are correct about playing very LF stuff.
One solution is to create a stereo track with one channel at f1 and the
other at f2 where f1>f2, feed these into a summing op-amp and follow by
some simple filtering to get f1-f2.

That will not work.
Click to expand...
In order to get (cerate, or generate) a sum or difference of
frequencies, one needs to use those signals to drive a nonlinear device.
Harmonics are also generated.
 
Robert Baer wrote:

Dirk Bruere at Neopax wrote:

Ban wrote:

Dirk Bruere at Neopax wrote:

Dirk Bruere at Neopax wrote:


Hi

Looking for a low frequency signal generator chip that can put out a
sine wave varying in frequency from around 1Hz to 100Hz with
resolution around 0.01Hz
Any ideas for a cheap solution?



Thanks for all the suggestions guys, and I'll keep them in mind.
However, I have decided the best (ie cheapest and hassle free)method
is to use a program like Audacity on a PC to generate the signal I
need to high precision. I can then either output it directly from the
soundcard or convert it to MP3 and play it from a portable device.




I was just checking out with my old copy of CEP what happens when you
add a 1Hz and a 1.01Hz sinewave. nice beat frequency.
The question is if the soundcard can output 1Hz without attenuating
it a bit. You should at least increase the output capacitors, so the
lower frequency -3dB point is 0.1Hz or less.



Well, as far as I know Audacity can create a tone at a very precise
frequency.
However, you are correct about playing very LF stuff.
One solution is to create a stereo track with one channel at f1 and
the other at f2 where f1>f2, feed these into a summing op-amp and
follow by some simple filtering to get f1-f2.

That will not work.
In order to get (cerate, or generate) a sum or difference of
frequencies, one needs to use those signals to drive a nonlinear device.
Click to expand...
Summing them won't work?

Harmonics are also generated.
Click to expand...
The f1+f2 can be filtered out. It should be easy if f1,f2 >> f1-f2

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
Robert Scott wrote:

On Wed, 27 Jul 2005 20:59:03 +0100, Dirk Bruere at Neopax
dirk@neopax.com> wrote:


..as far as I know Audacity can create a tone at a very precise frequency...


Unless you take some steps to calibrate to an external reference, the
generated tone can be no more accurate than the quartz crystal
timebase in your soundcard. And I have found these crystal
oscillators to be off by as much as 1%. That's not very precise. To
be fair, most soundcards are better than that. About .02%.
Click to expand...
The playback device could be anything from an MP3 player to a boombox.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
 
On Thu, 28 Jul 2005 06:34:26 GMT, the renowned Robert Baer
<robertbaer@earthlink.net> wrote:

In order to get (cerate, or generate) a sum or difference of
frequencies, one needs to use those signals to drive a nonlinear device.
Harmonics are also generated.
Click to expand...
Some audio editing software allows you to generate a modulated signal.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
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