How to make a Voltage Controlled Oscillator - Page 4

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Re: How to make a Voltage Controlled Oscillator
On Tue, 26 Oct 2010 17:30:53 -0700, Jim Thompson

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---
I'm still running at about 16kHz on the high end, but I sometimes have
trouble deciphering meaning from the Golden Girls' schtick.

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Re: How to make a Voltage Controlled Oscillator
On Tue, 26 Oct 2010 20:01:39 -0500, John Fields

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Recall the chart I posted.  Observe the sounds noted by a letter mark
at various SPL.  That's where all the intelligibility is.
        
                                        ...Jim Thompson
--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Re: How to make a Voltage Controlled Oscillator

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   You aren't fluent in 'Old lady'? ;-)


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Re: How to make a Voltage Controlled Oscillator
On Wed, 27 Oct 2010 02:24:03 +0200, "F. Bertolazzi"

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Why? Do you want to die?

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JF

Re: How to make a Voltage Controlled Oscillator
John Fields:

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Not in the next five years.

Re: How to make a Voltage Controlled Oscillator
On Tue, 26 Oct 2010 19:22:39 +0200, "F. Bertolazzi"

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Maybe you can't, i still can.  I could hear sine tones past 22,000 Hz as =
a
teen.

Re: How to make a Voltage Controlled Oscillator

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   I've had to scrap several SVGA monitors because I could hear the
horizontal sweep. :(


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Re: How to make a Voltage Controlled Oscillator

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Yes. That was the idea. A basic 8 bit ladder DAC connected to a
microcontroller. But as I understood the complexities like thermal
effects and tuning the oscillator to get even an octave of tuned sounds
out of 8 bits, This seems to be getting very complex for such a simple
project.

There are some digitally controlled oscillators, but they are just too
simple to control. They don't pose any challenge, and what is a hobby
without a challenge? I think I'll implement the oscillator and do the
mixing in the microcontroller.

You know guys, this always happens. Whenever I want to do something the
analog way, it always turns out to be too complex for a hobby project. I
guess I now understand why even the simplest machines by todays standards
were really expensive back in the day.

I never used a UJT, but 555 was my first IC, I programmed PICs and I run
Linux. :) I guess the art of analog circuits is kind of lost on my
generation.

Cheers!
Cem

Re: How to make a Voltage Controlled Oscillator


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Actually 256 frequencies (for an 8bit DAC) but I know what you mean. It
would have been very limited, and to tune the VCO so that all that 256
frequencies would be reasonably near a musical note would have been a
pain in the neck.
How do they do it in digital handheld radios? That oscillator has to span
a really large frequency range in tiny steps, yet it somehow manages. Is
there a really wide DAC there or a completely different approach to make
a DCO?

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I guess I'll opt for a software oscillator implemented in code. That will
be much more flexible I guess.

Cheers,
Cem

Re: How to make a Voltage Controlled Oscillator
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Does the uC not have an internal timer/oscillator circuit?  It's the best
way to go:
http://myweb.msoe.edu/williamstm/Solfeg_Fast.mp3

Heheh, I recorded this song from an 8MHz uC, but the song file was written
for 4MHz.  Sounds a little strange, overclocked.  The correctly formatted
song file plays in tune at a reasonable tempo, of course.

I have the AVR code used for this player, if that's any help.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms



Re: How to make a Voltage Controlled Oscillator

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This one is probably implemented with delay's (or if in assembly "nop"
loops), so it is monophonic. I will have to juggle 3 channels of output,
so I'll try to implement it on an interrupt. But thank you for your
offer :)

Cem

Re: How to make a Voltage Controlled Oscillator
Cem Uzunoglu:

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Are you familiar with Atmel's AVR controllers? Even the smallest ones have
at least one 16-bit PWM output. To change note, you simply have to load a
16-bit compare register. Take a look at the $1 ATtiny24 and his USI, that
would allow you to control even more than 3 devices by sending them only
note and duration.

--
Saluti

Re: How to make a Voltage Controlled Oscillator
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Yup!  Actually, in my particular use, I was already using the 16 bit
timer, so the tone generator uses one of the 8 bit timers.  With
prescaler, it acts more like a 10-16 bit timer, so the pitch accuracy is
still excellent.

The program only interrupts on note changes, so it takes very little
computing power overall.

It is somewhat memory intensive (maybe 1kB/min for typical songs), and
would benefit from a packed music format.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms



Re: How to make a Voltage Controlled Oscillator
Tim Williams:

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Thanks for the useful info.

But I narrowly convinced Cem to use only 7 octaves, and for that interval
16 bit + prescaler may turn out to be barely sufficient.

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Why? You had only one timer available?

--
Saluti

Re: How to make a Voltage Controlled Oscillator
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Well, it only needs one timer, but more to the point of data, that's
because of the format I chose.

Oops, I lied -- it does "almost" no computing during a note.  It does
perform an interrupt and decrement every timer reset.  I suppose if you
used two timers, you could remove that as well.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms



Re: How to make a Voltage Controlled Oscillator
Tim Williams:

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Right.

Re: How to make a Voltage Controlled Oscillator
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In the 1970s, I made a little tune player with an 8008. I had two
overlapping timing loops, one for the note, and another for the duration.

It was just rectangular waves, not strictly "tones", but it got the job
done. ;-)

Cheers!
Rich



Re: How to make a Voltage Controlled Oscillator
Rich Grise:

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In 1981 I did the same with a Z80, an EPROM and the few parts you can
easily imagine. It fitted in a cigarette pack and played "Lady Jane".

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Mine too: the girl I made it for become my girlfriend.

Seen in retrospect, I should have saved the time & money it took.
After a couple years I found her in bed with another engineer.

Mechanical, moreover.

Re: How to make a Voltage Controlled Oscillator
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I programmed my 8008 to do the tune of "Daisy, Daisy", since this
was shortly after the release of "2001: A Space Odyssey." :-)

Cheers!
Rich



Re: How to make a Voltage Controlled Oscillator
Rich Grise:

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The retarding version? :D

I just noticed that you referred to the fifth, not the sixth processor
designed by Federico Faggin. Oops, for a second I forgot that Bell invented
the telephone.

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