Cheap, simple way to generate 200Hz sine wave

[[email protected]]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

 

[Fred Bloggs]

Is there a simple way to generate a 200Hz sine wave? I'd like something

with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

That would be a "phase shift oscillator" made from a single supply
opamp. You can get 5% 200=10Hz accuracy using ordinary components
without tuning.

 

[David Harmon]

On Wed, 15 Mar 2006 02:48:30 GMT in sci.electronics.design, Fred

That would be a "phase shift oscillator" made from a single supply
opamp. You can get 5% 200=10Hz accuracy using ordinary components
without tuning.

So how do you get it down from there to the 1Hz that he mentioned
needing?

 

[PN2222A]

Is there a simple way to generate a 200Hz sine wave?

"You do know how to whistle, don't you, Steve?"

PN2222A

 

[[email protected]]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

I cant see an analoge solution at that price, you would need precision
components.

 

[Luhan]

The cost of the circuit needs to be less than 50

cents.

Your cost indicates a commercial project (unless you are a 10 year old
on an allowance). Yet, your question seems to indicate that you have
little idea what you are doing.

Just what are you doing?

 

[Christopher]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

Hello,

I am glad you asked because I found this little program and it works
awesome.

How about free! Use software forget about 2v to 3v.

http://www.world-voices.com/software/nchtone.html

Enjoy,

* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com

 

[[email protected]]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

0.5% accuracy without tuning knocks out any analog solution. If you can
geta a single chip microcontroller with a crystal controlled clock for
less than 50 cents - I suppose that this is possilbe if you buy enough
of them - you can then use one of Don Lancaster's "magic sinewave"
binary sequences to generate a pulse-width modulated output that will
be within 0.1% of 200Hz, and without much harmonic content below about
2kHz, which menas that you don't need much in the way of analog
filtering to clean up the output.

 

[Dave Farrance]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

There's no way that you'll get a stable 200 Hz +/-1 Hz oscillator
without expensive precision components - and even that will need
tuning.

How about generating a 200 Hz square wave with digital components, then
use a low-pass elliptic filter like the max7400 to chop off everything
but the fundamental. Lot more than 50c but it's probably one of the
cheaper solutions.

 

[Ancient_Hacker]

As others have noted, youy're unlikely to be able to get 1% stability
(I assume you mean frequency stability) without an adjustable pot, and
that's going to blow your budget, unless you're content with filing
away at a resistor to tune it.

About the lowest-cost really stable solution I can think of:

a tiny crystal (62 cents, Digi-Key)
an oscillator-divider chip (approx $1)
a few resistors to do a simple D/A ( 10 cents)
one transistor amplifier (12 cent transistor, two resistors)

Under $2. I don't think you can do much better than that, unless you
go to high quantities and have a custom microcpu masked.

 

[Fred Bloggs]

On Wed, 15 Mar 2006 02:48:30 GMT in sci.electronics.design, Fred



So how do you get it down from there to the 1Hz that he mentioned
needing?

Let him go hand pick his components until he gets there.

 

[Winfield Hill]

Fred Bloggs wrote...

Let him go hand pick his components until he gets there.

Silly fellows. I assume by "no tuning" acannell simply means a
fixed-frequency oscillator. Can a trimpot fit into his 50-cent
budget? I assume he's talking Pacific-rim prices for huge mass-
production quantities, so that should work. If not, then he has
to go the cheapest uP route and accept its oscillator accuracy.

 

[[email protected]]

Fred Bloggs wrote...

Silly fellows. I assume by "no tuning" acannell simply means a
fixed-frequency oscillator. Can a trimpot fit into his 50-cent
budget? I assume he's talking Pacific-rim prices for huge mass-
production quantities, so that should work. If not, then he has
to go the cheapest uP route and accept its oscillator accuracy.

I thought he meant no need for adjustment.

 

[John Fields]

Silly fellows. I assume by "no tuning" acannell simply means a
fixed-frequency oscillator. Can a trimpot fit into his 50-cent
budget? I assume he's talking Pacific-rim prices for huge mass-
production quantities, so that should work. If not, then he has
to go the cheapest uP route and accept its oscillator accuracy.

---
Silly you.

By "no tuning" I'm pretty sure he means that from a pile of parts in
front of him, none of which are variable, he wants to be able to
build an oscillator which will run at 200Hz +/- 1Hz out of the box.

 

[John Larkin]

Is there a simple way to generate a 200Hz sine wave? I'd like something
with no tuning involved, 1hz accuracy, powerable from 2 to 3V. I
believe harmonics are okay, but I dont know how to quanitify them. They
should be quiet enough to not be audible when listening to just the
tone on headphones. The cost of the circuit needs to be less than 50
cents.

Some things just aren't cheap and simple.

John

 

[[email protected]]

Thanks everyone for you responses. The project is a biofeedback device
which uses low frequency tones. By no tuning I meant literally no
tuning. I am assuming it will be too expensive to have some chinese
slave tune a pot and watch a frequency counter. (well I guess a slave
would be free, but who knows the way china is getting so capitalized) I
like the digital method using a filter and a 'magic pwm sequence'. I
had thought about doing this, basically a 1 bit digital audio recorder
using cheap flash, with the original audio (i.e. 200hz tone)
pre-encoded on a computer into a bitstream which 'matches' a given rc
filter response to recreate the audio.I will take a look at lancasters
work, I think that makes the most sense and would yield the most
flexible design (i.e. easy to try different frequencies).

Am I wrong or could you just generate a 200hz square wave and feed it
into a very steep slope low pass filter to get rid of all the
harmonics? Yes, I realize generating the 200hz +/- 1 hz square wave to
begin with is more than .50, but am I right about this being possible?

 

[GregS]

Thanks everyone for you responses. The project is a biofeedback device
which uses low frequency tones. By no tuning I meant literally no
tuning. I am assuming it will be too expensive to have some chinese
slave tune a pot and watch a frequency counter. (well I guess a slave
would be free, but who knows the way china is getting so capitalized) I
like the digital method using a filter and a 'magic pwm sequence'. I
had thought about doing this, basically a 1 bit digital audio recorder
using cheap flash, with the original audio (i.e. 200hz tone)
pre-encoded on a computer into a bitstream which 'matches' a given rc
filter response to recreate the audio.I will take a look at lancasters
work, I think that makes the most sense and would yield the most
flexible design (i.e. easy to try different frequencies).

Am I wrong or could you just generate a 200hz square wave and feed it
into a very steep slope low pass filter to get rid of all the
harmonics? Yes, I realize generating the 200hz +/- 1 hz square wave to
begin with is more than .50, but am I right about this being possible?

Is there really a need for low distorted sine wave? Filter the 200 off a divider
being fed a crystal oscillator. 50 cents??

greg

 

[GregS]

Is there really a need for low distorted sine wave? Filter the 200 off a
divider
being fed a crystal oscillator. 50 cents??

greg

Well some dividers have built in RC oscillators.

greg

 

[Rich Grise]

Thanks everyone for you responses. The project is a biofeedback device
which uses low frequency tones. By no tuning I meant literally no
tuning. I am assuming it will be too expensive to have some chinese
slave tune a pot and watch a frequency counter.

It would probably be cheaper to have a Chinese line worker twiddle
a pot for a few seconds than to find parts that will make an oscillator
good for +- .5% out of the box.

Why does the freq. have to be so tightly controlled? If it's "only"
biofeedback, how is the tone used? If it's just so the
victim^H^H^H^H^H^Hpatient can hear a tone, I seriously doubt if
a 190-210 Hz center freq. of the unit would make a difference, in
which case any ol' sine wave oscillator can do it.

What exactly are you trying to accomplish?

Thanks,
Rich

 

[Rich Grise]

"You do know how to whistle, don't you, Steve?"

Probably not at 200 Hz.

Cheers!
Rich