Stamp sound - sine waves
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Posts: 46,084
Speaking of sine-wave generation with a stamp....
I want to generate a variable frequency sine-wave that starts at 200 Hz and
sweeps down to 10 Hz or so over the period of a few seconds. I need to get
rid of the square-wave harmonics and make it relatively pure. Of course, a
simple RC low-pass filter won't work since picking a roll-off frequency for
a 200 Hz square-wave won't do a thing to round-off a 20 Hz square-wave. I've
thought about outputting the stamp to a D/A chip and driving a voltage
controlled oscillator like a Signetics 566 which makes a triangle wave
(closer to a sine-wav), but that seems like the long-way 'round. Does anyone
know of a binary driven variable-frequency oscillator chip with a sine-wave
output?
I guess the proper way could be a look-up table to synthesize an 8-bit sine
wave from the table via a D/A ... but I'm not sure I want to commit to that
much overhead within the stamp itself.
Am I making this too complicated, he mused....
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
I want to generate a variable frequency sine-wave that starts at 200 Hz and
sweeps down to 10 Hz or so over the period of a few seconds. I need to get
rid of the square-wave harmonics and make it relatively pure. Of course, a
simple RC low-pass filter won't work since picking a roll-off frequency for
a 200 Hz square-wave won't do a thing to round-off a 20 Hz square-wave. I've
thought about outputting the stamp to a D/A chip and driving a voltage
controlled oscillator like a Signetics 566 which makes a triangle wave
(closer to a sine-wav), but that seems like the long-way 'round. Does anyone
know of a binary driven variable-frequency oscillator chip with a sine-wave
output?
I guess the proper way could be a look-up table to synthesize an 8-bit sine
wave from the table via a D/A ... but I'm not sure I want to commit to that
much overhead within the stamp itself.
Am I making this too complicated, he mused....
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Comments
>I want to generate a variable frequency sine-wave that starts at 200 Hz and
>sweeps down to 10 Hz or so over the period of a few seconds. I need to get
>rid of the square-wave harmonics and make it relatively pure. Of course, a
>simple RC low-pass filter won't work since picking a roll-off frequency for
>a 200 Hz square-wave won't do a thing to round-off a 20 Hz square-wave. I've
>thought about outputting the stamp to a D/A chip and driving a voltage
>controlled oscillator like a Signetics 566 which makes a triangle wave
>(closer to a sine-wav), but that seems like the long-way 'round. Does anyone
>know of a binary driven variable-frequency oscillator chip with a sine-wave
>output?
http://www.fairchildsemi.com/ds/ML/ML2036IP.pdf
Might be suitable if your budget can withstand the cost. We've used these
in a couple of projects with no problems.
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 20 years of Engineering Innovation (1984 - 2004)
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collumn. This will generate a listing of values for a complete sine wave.
Make it a column. Next to the column assign values like D1 , D2, D3, with
the pull down function, the xls sheet will expand them automatically. Copy
that into a word document, or into the Pbasic program as text. This will
give you look up table values with little effort<G>.
Original Message
From: Mike Sokol [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=3G3pHhHSN0xl6X0VbmmJJ5C0ymOEc3AVfxy7LD5v9In1qCF_700uzfQSZDQaabNfqclT3F5q7L2YByuTRi4]mike@f...[/url
Sent: Wednesday, May 12, 2004 3:43 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Stamp sound - sine waves
Speaking of sine-wave generation with a stamp....
I want to generate a variable frequency sine-wave that starts at 200 Hz and
sweeps down to 10 Hz or so over the period of a few seconds. I need to get
rid of the square-wave harmonics and make it relatively pure. Of course, a
simple RC low-pass filter won't work since picking a roll-off frequency for
a 200 Hz square-wave won't do a thing to round-off a 20 Hz square-wave. I've
thought about outputting the stamp to a D/A chip and driving a voltage
controlled oscillator like a Signetics 566 which makes a triangle wave
(closer to a sine-wav), but that seems like the long-way 'round. Does anyone
know of a binary driven variable-frequency oscillator chip with a sine-wave
output?
I guess the proper way could be a look-up table to synthesize an 8-bit sine
wave from the table via a D/A ... but I'm not sure I want to commit to that
much overhead within the stamp itself.
Am I making this too complicated, he mused....
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"... -William of Occam-
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Thanks for the info on the Fairchild 2036. That could do the trick....
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "Dwayne Reid" <dwayner@p...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, May 12, 2004 4:04 PM
Subject: Re: [noparse][[/noparse]basicstamps] Stamp sound - sine waves
> At 01:43 PM 5/12/2004, Mike Sokol wrote:
>
> >I want to generate a variable frequency sine-wave that starts at 200 Hz
and
> >sweeps down to 10 Hz or so over the period of a few seconds. I need to
get
> >rid of the square-wave harmonics and make it relatively pure.
http://www.fairchildsemi.com/ds/ML/ML2036IP.pdf
Might be suitable if your budget can withstand the cost. We've used these
in a couple of projects with no problems.
Dwayne
(using a digital pot)?
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Mike Sokol [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=w7R6_VqVx0kWapMpMzm1-OhPV4WMjylXryKB-S08dVKqSjcPjjmYLKMn5-3v4ZNpkJzcbmg66o1zPBdAIQ]mike@f...[/url
Sent: Wednesday, May 12, 2004 2:43 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Stamp sound - sine waves
Speaking of sine-wave generation with a stamp....
I want to generate a variable frequency sine-wave that starts at 200 Hz
and sweeps down to 10 Hz or so over the period of a few seconds. I need
to get rid of the square-wave harmonics and make it relatively pure. Of
course, a simple RC low-pass filter won't work since picking a roll-off
frequency for a 200 Hz square-wave won't do a thing to round-off a 20 Hz
square-wave. I've thought about outputting the stamp to a D/A chip and
driving a voltage controlled oscillator like a Signetics 566 which makes
a triangle wave (closer to a sine-wav), but that seems like the long-way
'round. Does anyone know of a binary driven variable-frequency
oscillator chip with a sine-wave output?
I guess the proper way could be a look-up table to synthesize an 8-bit
sine wave from the table via a D/A ... but I'm not sure I want to commit
to that much overhead within the stamp itself.
Am I making this too complicated, he mused....
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"... -William of
Occam-
To UNSUBSCRIBE, just send mail to:
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This message has been scanned by WebShield. Please report SPAM to
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An alternative DDS chip, much more powerful for the about the same
price, is the AD9835 or AD9850 from Analog Devices
<http://www.analog.com/>. It uses a single supply and has a 32 bit
frequency control word. It outputs sine waves from 0.03 hz to 65
megahertz in steps of 0.0291 hz, and a direct phase modulation input
as well. There was discussion here on this list last last August
about how to calculate the control word using Stamp math.
Regarding <http://www.fairchildsemi.com/ds/ML/ML2036IP.pdf>, the
Fairchild web site says, "not recommended for new designs" on this
part, but they don't seem to have a substitute, and the same goes for
the 8-pin ML2035, with scaled down features. It would be nice to
have a simple small 8-pin chip that could generate accurate sine
waves with digital control
-- Tracy
>Dwayne,
>
>Thanks for the info on the Fairchild 2036. That could do the trick....
>
>Mike Sokol
>mike@f...
>www.fitsandstarts.com
>
>" One should not increase, beyond what is necessary,
>the number of entities required to explain anything"...
>-William of Occam-
>
>
Original Message
>From: "Dwayne Reid" <dwayner@p...>
>To: <basicstamps@yahoogroups.com>
>Sent: Wednesday, May 12, 2004 4:04 PM
>Subject: Re: [noparse][[/noparse]basicstamps] Stamp sound - sine waves
>
>
>> At 01:43 PM 5/12/2004, Mike Sokol wrote:
>>
>> >I want to generate a variable frequency sine-wave that starts at 200 Hz
>and
>> >sweeps down to 10 Hz or so over the period of a few seconds. I need to
>get
>> >rid of the square-wave harmonics and make it relatively pure.
>
> http://www.fairchildsemi.com/ds/ML/ML2036IP.pdf
>
> Might be suitable if your budget can withstand the cost. We've used these
> in a couple of projects with no problems.
>
> Dwayne