How to make a Voltage Controlled Oscillator - Page 6

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Re: How to make a Voltage Controlled Oscillator

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This one seems to require a password.

Re: How to make a Voltage Controlled Oscillator
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A 555, diddle the voltage on pin 5 (threshold?).

--

Tim Wescott
Wescott Design Services
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Re: How to make a Voltage Controlled Oscillator

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Does it work that way? I remember having to change a resistor value to
change the frequency. I remember threshold pin as used for PWM. I maybe
wrong though. It was a long time ago.

Re: How to make a Voltage Controlled Oscillator
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Here's a simple 1 volt/octave audio VCO:

http://i227.photobucket.com/albums/dd240/bitrex2007/VCO1.jpg

For best results, transistors Q1 to Q5 should be in thermal contact.  R4
can be made a trimmer pot to get an exactly 1 V/octave response.  R1 can
be a resistor with a temperature coefficient of -0.33%/degree C and also
put in thermal contact with the transistors to partly cancel the VT
temperature dependence of the differential pair.


Re: How to make a Voltage Controlled Oscillator
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oops, picture came out too small! Try zooming in on this link:

http://s227.photobucket.com/albums/dd240/bitrex2007/?action=view&current=VCO1.jpg


Re: How to make a Voltage Controlled Oscillator
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http://s227.photobucket.com/albums/dd240/bitrex2007/?action=view&current=VCO1.jpg
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One more time.  The site was resizing images as its new default setting.
  Sorry!

http://i227.photobucket.com/albums/dd240/bitrex2007/VCO1-1.jpg

Re: How to make a Voltage Controlled Oscillator
On Tue, 26 Oct 2010 13:08:09 -0400, Bitrex

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http://s227.photobucket.com/albums/dd240/bitrex2007/?action=view&current=VCO1.jpg
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Current Mirroring _way_ more complicated than need be ;-)
        
                                        ...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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555.

Cheers!
Rich


Re: How to make a Voltage Controlled Oscillator
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You're just baiting Bill Sloman, aren't you, Rich? :-)


Re: How to make a Voltage Controlled Oscillator

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Well, he did say, "simple." ;-)

Cheers!
Rich



Re: How to make a Voltage Controlled Oscillator

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But did that apply to the VCO, the 555, or Slowman.

Re: How to make a Voltage Controlled Oscillator
On Oct 27, 2:00A0%am, " snipped-for-privacy@att.bizzzzzzzzzzzz"
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Do pay attention. The original poster - Cem Uzunoglu - asked for "the
simplest VCO that can be done with off-the-shelf components". I went
for the VCO in the 4046 - and mentioned the AD654 which is simpler,
but less easily available (though Farnell still stocks it).

Rich Grise, being an idiot, suggested the 555, which can be made to
work as a sort of VCO. When it was suggested that he had done this
just to annoy me, his response clearly refers to the original request.
Why Rich should think that getting a 555 to work as a VCO is "simple"
escapes me - one can only imagine that he (like John Fields) finds it
difficult to get to grips with new devices and finds it easier to get
a familiar device to do what he wants as opposed to identifying a more
suitable modern device and working out how to use that.

Jim Thompson's circuit for getting a 555 to act as a VCO calls for
rather more external components than are required to get an AD654 to
work.

http://www.analog.com/static/imported-files/data_sheets/AD654.pdf

--
Bill Sloman, Nijmegen

--
Bill Sloman, Nijmegen

Re: How to make a Voltage Controlled Oscillator
On Wed, 27 Oct 2010 02:07:54 -0700 (PDT), Bill Sloman

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Since you're pretty much 555 illiterate, that's certainly no surprise.

Clue: Pin 5
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Re: How to make a Voltage Controlled Oscillator

Unfamilar as I am with the 555 (along with steam engines and horse-
driven wood-turning machinery), I relied on Jim Thompson's example of
the 555 as a VCO. You haven't yet described him as an idiot vis-a-vis
the 555 ....

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Jim Thompson has claimed that it is the CMOS version of his diabolical
biploar 4024/4044 VCO and phase detector (which I got to work back in
1972). It is certainly more modern (by a few years and an integrated
circuit manufacturing technology) than the 555.

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But it was explicitly designed for the job, and too specialised to be
manufactured in large enough numbers to make it really cheap. Cem
Uzunologlu doesn't seem to want to go into large scale production with
his device, so it might make sense for him to spend more money on a
specialised part which requires minimal design and development input.

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Why?

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But - as you have pointed out in other contexts - you've got to work
out how to program the B5%C you've selected, which isn't always that
simple.

--
Bill Sloman, Nijmegen



Re: How to make a Voltage Controlled Oscillator
On Wed, 27 Oct 2010 06:56:22 -0700 (PDT), Bill Sloman

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wrote:
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Why would I?

Unlike you, he picked the right device for the job.
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Re: How to make a Voltage Controlled Oscillator
et> wrote:
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Bearing in mind that you think the 555 is the "right device" for any
number of jobs.

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More modern - if not by much. The real distinction is that there are
almost always better ways of doing a job than with a 555, while the
4046 (and its derivatives) are still good solutions for many jobs that
involve a phase-locked loop. It always was a more specialised part
than the 555, but fulfilled it's particular function remarkably well.

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He's putting his own circuit together to do a job that he wants done.
That's design and development.

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True enough. But the competence that I developed with PDP-8 assembler
in 1968 doesn't translate directly into programming the lastest B5%C
from Arizona Microchip. It did make it easy to get a 6800 to do what I
wanted it to do some fifteen years later, but then I was taking
advantage of somebody else's development system and modifying his code
rather than putting something togehter from scratch.

--
Bill Sloman, Nijmegen


Re: How to make a Voltage Controlled Oscillator
On Wed, 27 Oct 2010 17:52:51 -0700 (PDT), Bill Sloman

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wrote:
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---
Being far more familiar with, and far less arbitrarily biased against
the 555 than you are, I'm in a much better position to judge its
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Re: How to make a Voltage Controlled Oscillator
On Thu, 28 Oct 2010 06:51:38 -0500, John Fields

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[snip]
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Slowman can't even do a hand analysis of how a 555 works internally.
If he got some "tools" he'd blow his head off :-)
        
                                        ...Jim Thompson
--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Re: How to make a Voltage Controlled Oscillator
On Oct 28, 6:04A0%pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
Web-Site.com> wrote:
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Why should I bother? I've got Hans Camenzind's "Designing Analog
Chips" which discusses the circuit in some detail. It isn't exactly a
complicated circuit.

If the worst came to the worst I could shoe-horn it into LTSpice and
play with it there.

--
Bill Sloman, Nijmegen

Re: How to make a Voltage Controlled Oscillator

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   I'll donate a couple screwdrivers...


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

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