On Wed, 24 Aug 2011 14:18:46 -0700 (PDT), davew <david.wooff@gmail.com>
wrote:

>
>> If you cough up answers to my questions on what you really need, folks
>> will be able to give you more specific help.
>>
>> I understand not wanting to break the digital barrier -- I tend to =
cross
>> that particular Rubicon with ease, yet I have circuits out there that =
are
>> all analog, or that only use "digital" parts in an analog way.
>
>I'm deliberately trying to make an all analogue design in this case so
>it's not that I'm particularly averse to taking a digital approach as
>such.
>
>>> * What frequency range does it need to run in? * How good does it =
have
>>> to be?
>LF to MF audio band probably 70Hz - 3KHz
>
>>>   * How quiet does it need to be?
>>>   How close to a sine does it need to be?
>Not sure really, I would have thought 2% THD+N would be good enough
>but I find it difficult to be accurate without having performed any
>experimentation yet.
>
>>>   * How linear does the command voltage vs. frequency need to be? *
>I can only answer "nominally" linear.  Definitely not log.
>
>>> * Temperature range?
>10 - 30 degC
>
>>> * what other questions did I leave out?
>Well I suppose the amplitude needs to be reasonably stable with
>frequency but again only to within say 10%.
>
>I think the XR2206 looks promising so far.  I've not yet had enough
>time to look at your other suggestions but will do.  I particularly
>like the idea of a Wien-bridge if it's easy enough to tune because
>there is no digital switching going on internally, so should be
>inherently more quiet.
>
>Many thanks to all.

You may be able to get the tuning range with a parallel-T oscillator and =
4
semi-matched lamp and photoresistor units.  It will produce a decent sine
wave as well.

?-)

John Larkin wrote:

> On Sat, 27 Aug 2011 19:44:12 -0700, RST Engineering
> <jweir43@gmail.com> wrote:
> 
> 
>>For the love of Jobs will you PLEASE learn how to snip.  PLEASE.
>>
>>Jim
> 
> 
> His entire post was only 25 lines!
> 
> John
> 
Hell, that's nothing, just getting warmed up

  Jamie

RST Engineering wrote:

> For the love of Jobs will you PLEASE learn how to snip.  PLEASE.
> 
> Jim
Ok,  you can stop stuttering now, I heard you the first time..

  Jamie

On Sat, 27 Aug 2011 19:44:12 -0700, RST Engineering
<jweir43@gmail.com> wrote:

>For the love of Jobs will you PLEASE learn how to snip.  PLEASE.
>
>Jim

His entire post was only 25 lines!

John

For the love of Jobs will you PLEASE learn how to snip.  PLEASE.

Jim

On Thu, 25 Aug 2011 14:25:22 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:

For the love of Jobs will you PLEASE learn how to snip.  PLEASE.

Jim

On Aug 27, 1:30=A0am, Tim Wescott <t...@seemywebsite.com> wrote:
> On Thu, 25 Aug 2011 20:29:45 -0700, Bill Sloman wrote:
> > On Aug 26, 5:26=A0am, Tim Wescott <t...@seemywebsite.com> wrote:
> >> On Wed, 24 Aug 2011 21:53:24 -0700,BillSlomanwrote:
> >> > On Aug 25, 3:24=A0am, Tim Wescott <t...@seemywebsite.com> wrote:
> >> >> On Wed, 24 Aug 2011 05:15:09 -0700,BillSlomanwrote:
> >> >> > On Aug 24, 7:22=A0pm, davew <david.wo...@gmail.com> wrote:
> >> >> >> I'm searching for a simple one chip solution if anyone has any
> >> >> >> ideas. Best I've found so far might be the old 8038 function
> >> >> >> generator chip.
>
> >> >> > If you are restricted to one chip, this is probably as good as it
> >> >> > gets. It distorts a triangular wave to a tolerable approximation
> >> >> > to a sine wave.
>
> >> >> > You can do better by feeding a square wave through a shift
> >> >> > register clock at some convenient multiple of the square wave
> >> >> > frequency, tying a series of resistors to the outputs of the shif=
t
> >> >> > register and summing the currents through the resistors into a
> >> >> > virtual earth to produce a staircase approximation to a sine wave=
,
> >> >> > but it takes quite a long shift register and quite a few close
> >> >> > tolerance resistors to do better than the 8038, and =A0it's still=
 a
> >> >> > three chip solution - basically a programmable logic device to
> >> >> > provide the shift register and the dividers to generate the squar=
e
> >> >> > wave, the VCO to to generate the clock at some fairly high
> >> >> > multiple of the output frequency, and an op amp to sum the
> >> >> > currents from the resistors, plus you have to find board space fo=
r
> >> >> > the resistors.
>
> >> >> > The Analog Devices DDS chips do provide a very good one chip
> >> >> > solution - the more expensive chips include 14-bit DACs - but it
> >> >> > isn't an analog solution.
>
> >> >> How about a CD4040 and a bunch of resistors? =A0(I think I mean the
> >> >> CD4040 -- the 4020, 4040, and 4060 are all big-ass counters, one of
> >> >> which has an oscillator built in).
>
> >> >> It's a ripple counter, but if you're going slow enough the clock
> >> >> glitches shouldn't get you too bad.
>
> >> > Well, the CD4040 is cheap, but a progammable logic device can provid=
e
> >> > the same funcion - and a lot more beside - in a single chip, which i=
s
> >> > one of the things the OP is asking for.
>
> >> > And the CD4040 is slow - slow enough for it to be nuisance when I
> >> > first used the part back in 1975. It looks glacial these days.
>
> >> At one point you could get 74HC4040 parts -- dunno if they're still ou=
t
> >> there.
>
> >> I was thinking of that part because of the built-in oscillator -- what
> >> programmable logic part has that?
>
> >http://www.datasheetcatalog.org/datasheet/philips/74HC4040.pdf
>
> > Some of the biggish CMOS counters RCA made at that time had built-in
> > oscillator drivers, but the 4040 wasn't one of them.
>
> Then -- as I stated in my original reply -- it's either the 4020 or the
> 4060

It was the 4060

http://www.futurlec.com/4000Series/CD4020.shtml

as if anybody cared. The original poster clearly isn't interested in
going down that route, and if he were he'd be more likely to go for a
programmable logic device which could provide all the logic he wanted
- including providing the gates to activate a simple oscillator - in a
single chip.

Sadly, he doesn't want to think about digitally-based solutions.

--
Bill Sloman, Nijmegen

On Fri, 26 Aug 2011 14:45:11 -0700, Jon Kirwan
<jonk@infinitefactors.org> wrote:

>On Wed, 24 Aug 2011 13:36:20 -0500, Tim Wescott
><tim@seemywebsite.com> wrote:
>
>>> Interesting ideas.  From memory, doesn't the Wien-bridge oscillator need
>>> some form of amplitude stabilisation?
>>
>>Yes, but if you don't mind a rather distorted sine wave it can be done 
>>just by letting the output smack into the supply rails.  Since you 
>>haven't responded to my questions about what you really need, one can 
>>only assume that any old wiggly line on a scope counts as a "sine" wave.
>
>National's AN-31 describes a "Wein Bridge Sine Wave
>Oscillator" on page 8, right side, using an incandescent bulb
>(Eldema 1869, with about 100k hr lifetime.)

Sorry, forgot to add that page 11 shows amplitude
stabilization using 2 BJTs and a JFET.

Jon

On Wed, 24 Aug 2011 13:36:20 -0500, Tim Wescott
<tim@seemywebsite.com> wrote:

>> Interesting ideas.  From memory, doesn't the Wien-bridge oscillator need
>> some form of amplitude stabilisation?
>
>Yes, but if you don't mind a rather distorted sine wave it can be done 
>just by letting the output smack into the supply rails.  Since you 
>haven't responded to my questions about what you really need, one can 
>only assume that any old wiggly line on a scope counts as a "sine" wave.

National's AN-31 describes a "Wein Bridge Sine Wave
Oscillator" on page 8, right side, using an incandescent bulb
(Eldema 1869, with about 100k hr lifetime.)

Jon