diy thermometer sensitivity

On Saturday, June 15, 2013 5:33:21 PM UTC-7, John Larkin wrote:

....

Just speculating, but if you just slowly add heat to a water-alcohol

mix, won't the alcohol boil off first? It's sort of self-regulating. I

don't know how pure the distillate would be.

After fermenting mixes of sugar, yeast and water, I noticed the liquid wouldn't start to boil until about 95 degrees C, and sometimes the collected distillate would catch fire, but not usually. If it did catch fire, there was a large puddle of water remaining in my saucer. That told me there was still a lot of water in the distillate.

In a commercial distillation column, they shove a fraction of the distillate back into the column (the fraction is called the Reflux Ratio) to get purer alcohol out. This also lowers the temperature inside the column.

 

[John Larkin]

On Sat, 15 Jun 2013 22:46:18 -0700, Daniel Pitts
<newsgroup.nospam@virtualinfinity.net> wrote:

On 6/15/13 4:28 PM, Jasen Betts wrote:
On 2013-06-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, June 14, 2013 6:58:18 PM UTC-7, David Eather wrote:

...

Did you say you are using Arduino? In which case you are programing in C

and the language will take care of the division and sign for you


Yes, I am, and I know.

I just wanted to clarify if I did do a bit shift to divide by 128,
would the sign be preserved if the delta happened to be negative.
Apparently the answer is no...

In assembler you use the ASR op-code *
In "C" the result is implementation defined, check your compiler
documentation.

I'd expect "avr-gcc" to get the answer right. which by reading the
assember output it appears to do (inefficiently)


(* actually in assmber for a divide by 128 you stash the low bit
(high bit of the low byte) move everything right by one byte, shift
the low bit back in and ripple up threough the intermediate bytes (if
any) and then restore the high byte using ADC and then CMP )

Why not just right-shift by 7?

I'm an 80x86 guy (and not the OP), but I'm curious about what you're
talking about here... It seems likely you've missed negative values, but
I could me missing the full thing.

So, lets say I have a 4 bit 2's compliment number, 1101 (-3). and I want
to divide by four. normal shifting will fail entirely, resulting in
0011 (3). Sign extended shifting will be closer, but still wrong 1111 (-1).

-3/4 = -0.75, which you can't express in 4 bits.

I would either need a real "divide" instruction, or I would need to
check the sign, and then if < 0, I would negate and shift and negate
back. Unless there is some other nifty trick I'm missing. I'd love to
see it.

Either way, if the OP wants to use (x >> 7) in C, they will find
negative values of x don't result in the desired value of x/128;

He needs more bits. If the ADC is 12 bits, load its data into the
upper 12 bits of a 16 bit word. Then you can signed-right-shift 4 and
not lose any bits.

Or load it into the ms 12 bits of a 32-bit word, and you can
shift/divide more.

I do some controllers in S32.32 math, signed 64 bits with the decimal
point in the middle. It's as good as floats for most any physical
reality, and much faster if you don't have hardware fp.

 

[Daniel Pitts]

On 6/16/13 8:49 AM, John Larkin wrote:

On Sat, 15 Jun 2013 22:46:18 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

On 6/15/13 4:28 PM, Jasen Betts wrote:
On 2013-06-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, June 14, 2013 6:58:18 PM UTC-7, David Eather wrote:

...

Did you say you are using Arduino? In which case you are programing in C

and the language will take care of the division and sign for you


Yes, I am, and I know.

I just wanted to clarify if I did do a bit shift to divide by 128,
would the sign be preserved if the delta happened to be negative.
Apparently the answer is no...

In assembler you use the ASR op-code *
In "C" the result is implementation defined, check your compiler
documentation.

I'd expect "avr-gcc" to get the answer right. which by reading the
assember output it appears to do (inefficiently)


(* actually in assmber for a divide by 128 you stash the low bit
(high bit of the low byte) move everything right by one byte, shift
the low bit back in and ripple up threough the intermediate bytes (if
any) and then restore the high byte using ADC and then CMP )

Why not just right-shift by 7?


I'm an 80x86 guy (and not the OP), but I'm curious about what you're
talking about here... It seems likely you've missed negative values, but
I could me missing the full thing.

So, lets say I have a 4 bit 2's compliment number, 1101 (-3). and I want
to divide by four. normal shifting will fail entirely, resulting in
0011 (3). Sign extended shifting will be closer, but still wrong 1111 (-1).

-3/4 = -0.75, which you can't express in 4 bits.
My example was meant to find the whole number result, truncating the

fractional part. This seems likely the use-case that the OP was
concerned with as well.

Actually, my point was (and I was too sleepy to think of it when I wrote
that), is that shift-right (if using a signed shift), will always
"floor" the result. Many people expect it to round toward zero, since
indeed that is what it does for positive integers.

I would either need a real "divide" instruction, or I would need to
check the sign, and then if < 0, I would negate and shift and negate
back. Unless there is some other nifty trick I'm missing. I'd love to
see it.

Either way, if the OP wants to use (x >> 7) in C, they will find
negative values of x don't result in the desired value of x/128;



He needs more bits. If the ADC is 12 bits, load its data into the
upper 12 bits of a 16 bit word. Then you can signed-right-shift 4 and
not lose any bits.

Or load it into the ms 12 bits of a 32-bit word, and you can
shift/divide more.

I do some controllers in S32.32 math, signed 64 bits with the decimal
point in the middle. It's as good as floats for most any physical
reality, and much faster if you don't have hardware fp.

 

[Jasen Betts]

On 2013-06-16, Daniel Pitts <newsgroup.nospam@virtualinfinity.net> wrote:

On 6/15/13 4:28 PM, Jasen Betts wrote:

In assembler you use the ASR op-code *
In "C" the result is implementation defined, check your compiler
documentation.

I'd expect "avr-gcc" to get the answer right. which by reading the
assember output it appears to do (inefficiently)


(* actually in assmber for a divide by 128 you stash the low bit
(high bit of the low byte) move everything right by one byte, shift
the low bit back in and ripple up threough the intermediate bytes (if
any) and then restore the high byte using ADC and then CMP )

I'm an 80x86 guy (and not the OP), but I'm curious about what you're
talking about here...

I would either need a real "divide" instruction, or I would need to
check the sign, and then if < 0, I would negate and shift and negate
back. Unless there is some other nifty trick I'm missing. I'd love to
see it.

Either way, if the OP wants to use (x >> 7) in C, they will find
negative values of x don't result in the desired value of x/128;

IIRC this was for signal processing and rounding towards 0 will
introduce crossover distortion so the rounding down that you get from
a bit shift is may be more useful,

--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Jasen Betts]

On 2013-06-16, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 15 Jun 2013 22:46:18 -0700, Daniel Pitts
newsgroup.nospam@virtualinfinity.net> wrote:

(* actually in assmber for a divide by 128 you stash the low bit
(high bit of the low byte) move everything right by one byte, shift
the low bit back in and ripple up threough the intermediate bytes (if
any) and then restore the high byte using ADC and then CMP )

Why not just right-shift by 7?

the only way to do that on the AVR is to shift right by 1 and repeat
that 7 times.

Overshoot then reverse by 1 is going to be atleast 4 times faster.

He needs more bits. If the ADC is 12 bits, load its data into the
upper 12 bits of a 16 bit word. Then you can signed-right-shift 4 and
not lose any bits.

yeah,

Or load it into the ms 12 bits of a 32-bit word, and you can
shift/divide more.

--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[George Herold]

On Jun 15, 8:33 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Wed, 12 Jun 2013 17:37:05 -0700 (PDT), George Herold





gher...@teachspin.com> wrote:
On Jun 12, 4:11 pm, mrdarr...@gmail.com wrote:
On Wednesday, June 12, 2013 12:36:25 PM UTC-7, George Herold wrote:

...

LM71 is nice, too.

+/- 1.5 degrees accuracy - he is trying to control to within 1 degree

(it almost sounds like he is trying to separate methanol from ethanol)

Your guess is pretty darned close

Michael- Hide quoted text -

- Show quoted text -

Oh, Are you distilling ethanol from water?

Haha, I plead the Fifth.  The closer I can get to the 95% EtOH-H2O azeotrope at around 78 degrees (seems like the exact number depends on which source you read 78.2? 78.3? 78.5? I give up)

I'm pretty sure, (though I don't know for sure... like if I did the
measurement) that the temperature will change with external pressure,
so What's your altitude, and is there a cold front passing through?

I'm thinking of water, where at higher altitudes, you've gotta boil
your eggs for more than 6.5 minutes, for that hard white, soft yellow
that I like.

First time I did mashed potatoes up here in Truckee, they came out
raw. It takes a full hour. At higher altitudes, it might not be
possible without a pressure cooker.

Just speculating, but if you just slowly add heat to a water-alcohol
mix, won't the alcohol boil off first? It's sort of self-regulating. I
don't know how pure the distillate would be.- Hide quoted text -

- Show quoted text -

I'm guessing that unless it starts to boil, you just don't get much
vapor.
(I was going to suggest sci.chem... but that looks to be full of many
of the same 'characters' as are on sci.physics.)
(maybe we could ask Bill Sloman on SED?)

You'll get some partial pressure of each gas in the vapor.
I should dig up my general chem. book. I don't recall any sort of
practial discussion of distillation... maybe that's only covered in
chem. eng.

George H.

 

On Monday, June 17, 2013 7:41:43 AM UTC-7, George Herold wrote:

On Jun 15, 8:33 pm, John Larkin

jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Wed, 12 Jun 2013 17:37:05 -0700 (PDT), George Herold











gher...@teachspin.com> wrote:

On Jun 12, 4:11 pm, mrdarr...@gmail.com wrote:

On Wednesday, June 12, 2013 12:36:25 PM UTC-7, George Herold wrote:



...



LM71 is nice, too.



+/- 1.5 degrees accuracy - he is trying to control to within 1 degree



(it almost sounds like he is trying to separate methanol from ethanol)



Your guess is pretty darned close



Michael- Hide quoted text -



- Show quoted text -



Oh, Are you distilling ethanol from water?



Haha, I plead the Fifth.  The closer I can get to the 95% EtOH-H2O azeotrope at around 78 degrees (seems like the exact number depends on which source you read 78.2? 78.3? 78.5? I give up)



I'm pretty sure, (though I don't know for sure... like if I did the

measurement) that the temperature will change with external pressure,

so What's your altitude, and is there a cold front passing through?



I'm thinking of water, where at higher altitudes, you've gotta boil

your eggs for more than 6.5 minutes, for that hard white, soft yellow

that I like.



First time I did mashed potatoes up here in Truckee, they came out

raw. It takes a full hour. At higher altitudes, it might not be

possible without a pressure cooker.



Just speculating, but if you just slowly add heat to a water-alcohol

mix, won't the alcohol boil off first? It's sort of self-regulating. I

don't know how pure the distillate would be.- Hide quoted text -



- Show quoted text -



I'm guessing that unless it starts to boil, you just don't get much

vapor.

Yup. It then becomes a diffusion problem (super slow compared to boiling). http://en.wikipedia.org/wiki/Fick%27s_law

Now that I remember back from Organic Chem class, there is vacuum distillation. Less heat required for boiling, but now it's a trade-off because you have to power the vacuum pump.
https://en.wikipedia.org/wiki/Vacuum_distillation

I remember using vacuum distillation to make DEET in Organic Chem class, I think it was because the DEET would decompose at atmospheric boiling temperatures.

(I was going to suggest sci.chem... but that looks to be full of many

of the same 'characters' as are on sci.physics.)

(maybe we could ask Bill Sloman on SED?)



You'll get some partial pressure of each gas in the vapor.

Yup, Henry's Law and Raoult's Law. Ethanol-Water mixtures are non-ideal solutions though (the ethanol and water molecules like each other too much)

https://en.wikipedia.org/wiki/Henry's_law
http://en.wikipedia.org/wiki/Raoult's_law

Oh yeah, fugacity coefficients. These guys explain it much better than my Thermo text ever did...

http://en.wikipedia.org/wiki/Fugacity_coefficient

I should dig up my general chem. book. I don't recall any sort of

practial discussion of distillation... maybe that's only covered in

chem. eng.



George H.

I'm a refugee from sci.engr.chem personally =)

It's discussed a little bit in Organic Chemistry (chemistry for second-year Biology and Chemistry majors.)

 

[Steve Gonedes]

George Herold <gherold@teachspin.com> writes:

< Say, isn't it legal to distill some of your own hooch in the US?
< Maybe you need a permit/ license?

As far as I know condensation of any liquid is illegal in the united
states - let alone distillation. Fermentation doesn't seem to be a
problem so long as the local bomb sqaud doesn't confiscate all your
worldly posessions.

If they find out that you are actually trying to condense water they
become very aggregated and start to insist that your are hinding
something. Maybe it's in the ``ether''? still dunno.

 

[Steve Gonedes]

Jon Kirwan <jonk@infinitefactors.org> writes:

< getting appropriate laboratory equipment and/or teflon and

The use of teflon is not legal. It contains floride wich is a
non-potable metal contaminate (i.e., water that contains floride from
unnatural sources is considered "unsafe to drink".). I am unable to find
an MSDS on PTFE T-27730A on the google.


< food grade stainless) allowed legislators to justify keeping
< a strong hold on the tax revenues for hard liquors.

what is food grade steel? just curious.

< What I did find is that if you are a "moonshiner" then you
< need to secure at least one federal permit and pay taxes on
< what you produce, even if only for personal use. I would
< assume that if you sell any of it, that would be at least one
< more permit, probably more fees, and probably inspections and
< fees for that and who knows what else (appropriate bribes,
< etc?)

I believe the big issue is "the transport of distilled spirits". It is
not legal to transport distilled spirits - even as evidence (this may
vary accorrding to which state the "transportation occured" in.). One
raises the question - what is in the bottle, no?

< I didn't dwell on it.)

Me either.

 

[Steve Gonedes]

mrdarrett@gmail.com writes:

< It is rather odd that on Question 11 they would ask for the capacity. How
< would I know what the capacity is unless I build it?

They probably want to know what strain of yeat(s) you are using. If I
remember correctly some yeast will "die off" at 14% alcohol. You might
need to count your grains of corn and grains of sugar.

 

[Jon Kirwan]

On Thu, 27 Jun 2013 22:46:44 -0300, Steve Gonedes
<steve@mail.comcast.net> wrote:

Jon Kirwan <jonk@infinitefactors.org> writes:
snip

food grade stainless) allowed legislators to justify keeping
a strong hold on the tax revenues for hard liquors.

what is food grade steel? just curious.
snip

I'm no expert. I was simply cautioned to specify food grade
stainless and contruction methods when buying some long term
storage containers, so I did and wasn't questioned about it
when I ordered them. I had done a little reading before,
though, and the following summarizes what I'd gathered up.

There are certain types of stainless alloys and annealing
used for food handling and containers. I gather what is used
depends upon the use and the construction. I've read about
types 302, 303, 304, 316, 420, and 430. (303 doesn't weld
well, but machines okay, for example. So an application which
requires welding wouldn't use it.) I think there is more than
just "type" involved. For example, there are 304L and 316L
types used for food. You may also have to watch out for
additives, like sulfur, used to improve machining. Type
number alone may not tell you all you need to know.

From "The Making and Shaping of Steel" from United States
Sttel: Type 302, austenitic 18-8 with 0.15% max carbon, 8% to
10% nickel, and 17% to 19% chromium is corrosion resistant
and has good ductility and may be deep drawn and formed. It
may also be welded if the heat zones are cooled rapidly.
(Otherwise intergrannular corrosion may happen in the welds.
But that can be corrected by annealing above 1900F, followed
by rapid cooling to trap the carbides in situ.)

It's also not only a type of steel but also how you handle
the design and finishing methods to sufficiently reduce pits
or anything else that may promote bacterial growth and also
to provide surfaces that can be reliably (repeatably) cleaned
and sanitized. You know, the welds need to be smooth for
example and not deeply pitted, for example.

But you can't ignore the type of steel. The selection is
limited by the food it will contain, duration, environment,
and the methods of cleaning and reuse.

I wish I knew more about the subject, but I'm a consumer not
a designer of these products.

Jon

 

On Thursday, June 27, 2013 9:34:27 PM UTC-7, Jon Kirwan wrote:

On Thu, 27 Jun 2013 22:46:44 -0300, Steve Gonedes

steve@mail.comcast.net> wrote:



Jon Kirwan <jonk@infinitefactors.org> writes:

snip



food grade stainless) allowed legislators to justify keeping

a strong hold on the tax revenues for hard liquors.



what is food grade steel? just curious.

snip



I'm no expert. I was simply cautioned to specify food grade

stainless and contruction methods when buying some long term

storage containers, so I did and wasn't questioned about it

when I ordered them. I had done a little reading before,

though, and the following summarizes what I'd gathered up.



There are certain types of stainless alloys and annealing

used for food handling and containers. I gather what is used

depends upon the use and the construction. I've read about

types 302, 303, 304, 316, 420, and 430. (303 doesn't weld

well, but machines okay, for example. So an application which

requires welding wouldn't use it.) I think there is more than

just "type" involved. For example, there are 304L and 316L

types used for food. You may also have to watch out for

additives, like sulfur, used to improve machining. Type

number alone may not tell you all you need to know.



From "The Making and Shaping of Steel" from United States

Sttel: Type 302, austenitic 18-8 with 0.15% max carbon, 8% to

10% nickel, and 17% to 19% chromium is corrosion resistant

and has good ductility and may be deep drawn and formed. It

may also be welded if the heat zones are cooled rapidly.

(Otherwise intergrannular corrosion may happen in the welds.

But that can be corrected by annealing above 1900F, followed

by rapid cooling to trap the carbides in situ.)



It's also not only a type of steel but also how you handle

the design and finishing methods to sufficiently reduce pits

or anything else that may promote bacterial growth and also

to provide surfaces that can be reliably (repeatably) cleaned

and sanitized. You know, the welds need to be smooth for

example and not deeply pitted, for example.



But you can't ignore the type of steel. The selection is

limited by the food it will contain, duration, environment,

and the methods of cleaning and reuse.



I wish I knew more about the subject, but I'm a consumer not

a designer of these products.



Jon

Food grade... this is not exactly my field either, but you certainly don't want lead in any welds.

18/10 and 18/0 (first number is percent chromium, second # is percent nickel) seem popular in "food grade" stainless steels. Personally I dislike nickel since some have allergies to it. I look for 18/0 in my cookware personally. And besides, iron and chromium are important minerals. Copper too (I think the early Alambic stills were made of copper.) Nickel and lead, not so much.

Michael