Audio frequency generator?
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Posts: 46,084
Hello everyone,
I'm looking for a good way to generate different audio
tones. Freqout works well, but ties up the stamp so that it can't do
anything else. I want something simple (an oscillator of some type) that
the stamp can turn on and then go about it's business. Does a 555 generate
square waves or sine waves? Any other suggestions?
Duncan
I'm looking for a good way to generate different audio
tones. Freqout works well, but ties up the stamp so that it can't do
anything else. I want something simple (an oscillator of some type) that
the stamp can turn on and then go about it's business. Does a 555 generate
square waves or sine waves? Any other suggestions?
Duncan
Comments
You could use a 555, which generates square waves, and pass the square waves
thru a simple lowpass RC network. The better you filter, the less output,
so you may need to amplify it, depending on your application.
555
R
Output
|
C
|
GND
R & C value depend on frequency..try 1K and ~2uf. If load is high Z, could
use 10K & ~0.2uf.
Ray McArthur
Original Message
From: <orthner@s...>
To: <basicstamps@egroups.com>
Sent: Tuesday, April 11, 2000 9:53 PM
Subject: [noparse][[/noparse]basicstamps] Audio frequency generator?
>
> Hello everyone,
>
> I'm looking for a good way to generate different audio
> tones. Freqout works well, but ties up the stamp so that it can't do
> anything else. I want something simple (an oscillator of some type) that
> the stamp can turn on and then go about it's business. Does a 555 generate
> square waves or sine waves? Any other suggestions?
>
> Duncan
>
>
>
it's available. Who cares if the signal is a square or a sine wave
anyway?
Please check out: [url=HTTP://www.findchips.com/]HTTP://www.findchips.com/[/url] for a source of suppliers.
Jameco has them for about $4. A data sheet is available also there.
Leroy
rjmca wrote:
>
> Duncan:
> You could use a 555, which generates square waves, and pass the square waves
> thru a simple lowpass RC network. The better you filter, the less output,
> so you may need to amplify it, depending on your application.
>
> 555
R
Output
> |
>
>
C
> |
> GND
> R & C value depend on frequency..try 1K and ~2uf. If load is high Z, could
> use 10K & ~0.2uf.
>
> Ray McArthur
>
>
Original Message
> From: <orthner@s...>
> To: <basicstamps@egroups.com>
> Sent: Tuesday, April 11, 2000 9:53 PM
> Subject: [noparse][[/noparse]basicstamps] Audio frequency generator?
>
> >
> > Hello everyone,
> >
> > I'm looking for a good way to generate different audio
> > tones. Freqout works well, but ties up the stamp so that it can't do
> > anything else. I want something simple (an oscillator of some type) that
> > the stamp can turn on and then go about it's business. Does a 555 generate
> > square waves or sine waves? Any other suggestions?
> >
> > Duncan
> >
> >
> >
--
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Micro Linear makes an interesting series of sine wave generator chips that
are serially programmable and very precise. Look up ML2035~7 at
www.microlinear.com. I don't know if anyone has used them with Stamps...
> I'm looking for a good way to generate different audio
>tones. Freqout works well, but ties up the stamp so that it can't do
>anything else. I want something simple (an oscillator of some type) that
>the stamp can turn on and then go about it's business. Does a 555 generate
>square waves or sine waves? Any other suggestions?
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
> Freqout works well, but ties up the stamp so that it can't
> doanything else. I want something simple (an oscillator of some
> type) thatthe stamp can turn on and then go about it's business.
> Does a 555 generatesquare waves or sine waves? Any other suggestions?
"Art of Electronics" table 5.4 lists many VCO (Voltage controlled
oscillator) chips. One easy possibility if you can use a square wave with
not too great stability, is the CD4046 PLL chip. It contains a VCO you
could drive directly through an RC circuit with the PWM command from the
stamp to program the frequency. Just return from time to time to refresh
the PWM voltage. At the high end, there are modules on the market that
can be programmed via RS232 or parallel to sythesize highly accurate,
stable sine waves.
-- Tracy Allen
Electronically Monitored Ecosystems
http://www.emesystems.com
>You could use a 555, which generates square waves, and pass the square waves
>thru a simple lowpass RC network. The better you filter, the less output,
>so you may need to amplify it, depending on your application.
Thanks Ray, I knew you'd come up with something 8^]. I'd like to use a 555
but can't see how I can change the frequency with the stamp (I need eight
tones). Does the RC circuit charge/discharge on every oscillation? I guess
I could use eight 555's...
Thanks, Duncan
>An 8038 produces sine waves, the last time I checked. Don't know where
>it's available. Who cares if the signal is a square or a sine wave
>anyway?
Audio tones are sine waves. I checked the datasheet for this device and it
looks great. I'll order some today...
Thanks, Duncan
I don't know of a simple, "clean" way to set multiple tones with a 555. It
can be done, (like turning on 1 of 7 additional transistors), but it should
be compared to other approaches. I would check out some of the other ICs
that were posted in response to your message. For example Mike Hardwick's
suggestion:
Micro Linear makes an interesting series of sine wave generator chips that
are serially programmable and very precise. Look up ML2035~7 at
www.microlinear.com. I don't know if anyone has used them with Stamps...
A serially programmed chip may allow sending one serout command, after which
the stamp can do other work.
or Tracy's suggestion: CD4046 PLL chip, using the VCO. This would require
periodic updates to the PWM voltage.
Eight 555's would be simple to set up, but lots of hardware.
Ray McArthur
Original Message
From: <orthner@s...>
To: <basicstamps@egroups.com>
Sent: Thursday, April 13, 2000 7:23 AM
Subject: Re: [noparse][[/noparse]basicstamps] Audio frequency generator?
> At 01:56 AM 4/12/00 -0400, Ray wrote:
>
> >You could use a 555, which generates square waves, and pass the square
waves
> >thru a simple lowpass RC network. The better you filter, the less
output,
> >so you may need to amplify it, depending on your application.
>
> Thanks Ray, I knew you'd come up with something 8^]. I'd like to use a 555
> but can't see how I can change the frequency with the stamp (I need eight
> tones). Does the RC circuit charge/discharge on every oscillation? I guess
> I could use eight 555's...
>
> Thanks, Duncan
>
>
>
> At 04:09 AM 4/12/00 -0400, Leroy wrote:
>
> >An 8038 produces sine waves, the last time I checked. Don't know where
> >it's available. Who cares if the signal is a square or a sine wave
> >anyway?
>
> Audio tones are sine waves. I checked the datasheet for this device and it
> looks great. I'll order some today...
Um...No.
In traditional electronic synthesis, Audio tones can be sine, triangle,
square, usually with filters on the top of them. for "real" sounds,
they're often much, much more complex. This is where the popular
"wavetable synthesis" comes from"
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"...There's no moral, it's just a lot of stuff that happens". - H. Simpson
>
>In traditional electronic synthesis, Audio tones can be sine, triangle,
>square, usually with filters on the top of them. for "real" sounds,
>they're often much, much more complex. This is where the popular
>"wavetable synthesis" comes from"
So I can generate eight distinct, clear tones with positive-going 0-5v
square pulses? This would simplify things a bit...
Duncan
The first is a chip called a "melody tone generator". It generates all
of the musical scale frequencies by inputing a digital address. This
may require quite a few stamps pins. It used to be sold by radio shack
but I don't know where you's get one now.
The second solution is quite fancy. The AY3-8910 is a 3 channel
ASDR synthesizer chip. You program the Attack, Delay,Sustain,
and Release values into the chip to create an audio waveform.
With 3 channels, you can mix to create complex layered sounds.
The chip has a simple digital interface, the programming is left
to the end user. Good Luck.
> At 12:49 PM 4/13/00 -0700, Sean wrote:
> >
> >In traditional electronic synthesis, Audio tones can be sine, triangle,
> >square, usually with filters on the top of them. for "real" sounds,
> >they're often much, much more complex. This is where the popular
> >"wavetable synthesis" comes from"
>
> So I can generate eight distinct, clear tones with positive-going 0-5v
> square pulses? This would simplify things a bit...
Yes. It's a bit more "tinny" of a sound.
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"...There's no moral, it's just a lot of stuff that happens". - H. Simpson
using a 555 timer and selecting different resistors with the stamp. Simple,
cheap and works great. For any application requiring higher precision, I
think the serial VCO's would be better - I'm getting approx. 1% variation
in frequency. For audio tones it works fine!
Thanks again, Duncan
(Don't know what I would do without this list)