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'[EE] DIY drink cooler using a Peltier element'
2011\04\08@050304 by V G

picon face
I can't find any decent drink cooler and I always wanted one. So I want to
make one, something like this:

* Consists of one or more Peltier elements.
* Hot side of the element is connected to a good, cheap, CPU heatsink and
fan.
* Goal is to cool to 1 - 3 degrees C.

* Power consumption is not an issue. Really want to hit that 1 - 3 degree C
target.
* Size: should be reasonably sized to fit on a desk beside the computer.
* Noise isn't too much of a concern. Most CPU cooling fans are pretty quiet
anyway and offer great cooling.

* The top of the cooler would probably just consist of a metal plate where a
drinking glass or a metal beer can would sit. As for metal cans, the heat
removal would be more than enough to keep the drink cool. As for glass
drinking cups, I'd certainly hope that the rate of heat removal is greater
or equal to the rate of heat gained by the drink. Thoughts on this?

* Should the Peltier element be "temperature controlled"?

Anyone have any idea where I can get cheap Peltier elements in various
sizes?

Any other ideas to keep a drink cool while on the desk

2011\04\08@055307 by alan.b.pearce

face picon face
{Quote hidden}

There are some tricks to making a Peltier unit run most efficiently, like you need to supply them with a pure DC source. I have a tiny experience designing a switch mode converter to supply one, and ended up using a synchronous rectification to minimise the losses in the flyback diode of the buck regulator.

If you don't supply them with pure Dc then you get heating effects on the cooling side of the Peltier.
-- Scanned by iCritical.

2011\04\08@060011 by V G

picon face
On Fri, Apr 8, 2011 at 5:52 AM, <spam_OUTalan.b.pearceTakeThisOuTspamstfc.ac.uk> wrote:

>  There are some tricks to making a Peltier unit run most efficiently, like
> you need to supply them with a pure DC source. I have a tiny experience
> designing a switch mode converter to supply one, and ended up using a
> synchronous rectification to minimise the losses in the flyback diode of the
> buck regulator.
>
> If you don't supply them with pure Dc then you get heating effects on the
> cooling side of the Peltier.
>

I intend to supply it with a purely DC source. I'm going to take the power
straight from my +5 or +12 rail out of the computer's PSU, or a spare PSU I
have lying around. I love those PSUs. Lots of power, convenient voltage, can
be used for anything

2011\04\08@061315 by Ruben Jönsson

flavicon
face
>
> Any other ideas to keep a drink cool while on the desk?
> --
No, but if you are going to use a peltier you can make it reversible so it also can keep a hot drink hot.

/Ruben


==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
.....rubenKILLspamspam@spam@pp.sbbs.se
==============================

2011\04\08@063109 by alan.b.pearce

face picon face
> I intend to supply it with a purely DC source. I'm going to take the power
> straight from my +5 or +12 rail out of the computer's PSU, or a spare PSU I
> have lying around. I love those PSUs. Lots of power, convenient voltage, can
> be used for anything.

Yeah, well depending on how many devices you use, each one will want somewhere between 1V and 1.5V, so you won't be able to 'just' buy a device and hook it to the power supply, unless it comes with its own power converter.

I don't know how the car chiller devices work, they will have some form of control electronics in them, but may also run several Peltier devices in series, to get closer to the 12V input.
-- Scanned by iCritical.

2011\04\08@063202 by Justin Richards

face picon face
> I intend to supply it with a purely DC source. I'm going to take the power
> straight from my +5 or +12 rail out of the computer's PSU, or a spare PSU I
> have lying around. I love those PSUs. Lots of power, convenient voltage, can
> be used for anything.
> --
Not sure if PSU supplies are that pure.  I see pure = $$$ and would
suspect ripple on all the DC rails as most components can handle some
ripple.

But I think any ripple here would equal heat.

Just looking at a specs for a brand name PSU and the quote 1% rippl

2011\04\08@070032 by IVP

face picon face
> Any other ideas to keep a drink cool while on the desk?

Use a Miles Davis CD as a coaste

2011\04\08@074046 by V G

picon face
On Fri, Apr 8, 2011 at 6:32 AM, Justin Richards
<justin.richardsspamKILLspamgmail.com>wrote:

> Not sure if PSU supplies are that pure.  I see pure = $$$ and would
> suspect ripple on all the DC rails as most components can handle some
> ripple.
>
> But I think any ripple here would equal heat.
>
> Just looking at a specs for a brand name PSU and the quote 1% ripple


Is that going to be a *lot* of excess heat?

Is there a way to stabilize the output?

What about bypass capacitors? Linear regulators? I think it'll be difficult
finding regulators to supply *that* much current

2011\04\08@081524 by Spehro Pefhany

picon face
At 06:32 AM 4/8/2011, you wrote:
> > I intend to supply it with a purely DC source. I'm going to take the power
> > straight from my +5 or +12 rail out of the computer's PSU, or a spare PSU I
> > have lying around. I love those PSUs. Lots of power, convenient
> voltage, can
> > be used for anything.
> > --
>Not sure if PSU supplies are that pure.  I see pure = $$$ and would
>suspect ripple on all the DC rails as most components can handle some
>ripple.
>
>But I think any ripple here would equal heat.

There is not much improvement to be had below 10% ripple. It's an RMS vs.
average thing, compounded by the dismal performance of Peltiers vs.
mechanical refrigeration at the best of times. See app notes for Peltiers.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speffKILLspamspam.....interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

2011\04\08@090806 by Olin Lathrop

face picon face
Justin Richards wrote:
>> I intend to supply it with a purely DC source. I'm going to take the
>> power straight from my +5 or +12 rail out of the computer's PSU, or
>> a spare PSU I have lying around. I love those PSUs. Lots of power,
>> convenient voltage, can be used for anything.
>
> Not sure if PSU supplies are that pure.  I see pure = $$$ and would
> suspect ripple on all the DC rails as most components can handle some
> ripple.
>
> But I think any ripple here would equal heat.
>
> Just looking at a specs for a brand name PSU and the quote 1% ripple

You are going a bit off the deep end.  You need to go back to the basics and
see what this is all about rather than relying on rules of thumb with long
forgotten derivations.

This issue is that the efficiency (final resulting cooling power per
electrical input power) of Peltier coolers goes down the harder they are
driven, although the total cooling power still goes up to some maximum point
specified in the datasheet.  Let's say you want 50% of the total cooling
power the device is capable of.  You can get that cooling power by a 50%
duty cycle of full power or a steady input resulting in 1/2 output power.
Both cause the same cooling, but the first uses more electrical power
because the device is more efficient at the lower power operating point.

Taken to the extreme, any deviation from running the cooler with a steady DC
current causes inefficiency.  You can contort this to say that "ripple" is
bad in that it causes inefficiency, but small deviations from the average
operating point aren't going to significantly matter.  Any regulated power
supply is going to be good enough.

If you are doing active temperature control, what you don't want to do is
the otherwise obvious PWM control of a Peltier cooler (like would be
appropriate for a resistive heater).  You essentially want to smoothly
control a reasonably filtered analog current.  However, that presents some
problems in itself.  If you are going to derive this current by linearly
regulating a fixed voltage power supply, then you're just wasting the extra
power elsewhere.  Maybe that helps because it's physically in a different
place where it may not matter as much getting hot or it's easier to get rid
of the heat.  However, if power efficiency is the goal that's not going to
help.

This is why Peltier coolers are usually driven by what amounts to a variable
switching power supply, but with enough filtering to keep the total ripple
to a small fraction of the average output.  Anything that would qualify as a
regulated power supply for other purposes would likely be good enough.


********************************************************************
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(978) 742-9014.  Gold level PIC consultants since 2000

2011\04\08@104237 by Walter Banks

picon face


V G wrote:

> Anyone have any idea where I can get cheap Peltier elements in various
> sizes?

The amateur telescope guys use Peltier elements to cool their
camera's. That is where I would look for design information
and part sources.

Regards,


w..
--
Walter Banks
Byte Craft Limited
http://www.bytecraft.com


2011\04\08@105223 by Dr Skip

picon face
I've found them at various electronic and/or science surplus places.

- Skip




>V G wrote:
>
>> Anyone have any idea where I can get cheap Peltier elements in
>various
>> sizes

2011\04\09@231448 by Al Shinn

picon face
VG
Look on EBAY
search Peltier cooler
There are many.
I ordered a TEC1-12706 May 30 from "Cheaper Buy" $2.79 with free shipping  It came today -  the hot side gets hot and the cold side, cold so it seems OK   "Cheaper Buy" seems to have vanished but there are many more from $1 with a few bucks shipping.
in the PN, the:
TE is for Thermoelectric ?
C is for standard size
1 is for stages
127 is for number of couples
the 06 is for Amps

This TEC1-12706 is supposed to draw 6 Amps at 12 V. I have not yet measured it for that - just that when I put it into the mini fridge it started to cool but I had to turn it off pretty soon cause the hot side fan is  blown out.
The little fridge label says "DC12V  AC100V  /  36W  50Hz"
But it means that a (missing) adapter is for 100V  - Someone interpreted that literally and smoked it rather completely.
I have already blacked out that stupid 100V
The TE I am replacing is a TEC1-12704 so my new mini fridge will have more oomph.
Bottom line,  If you have 12V with 6 Amps, there are lots of these things on EBAY. Also different current ones if you want - but no 04s.
I think all of the **127* ones are 12V.

VG wrote:
>Anyone have any idea where I can get cheap Peltier elements in various
>sizes?


--
Looking forward,
Al Shinn

2011\04\10@014832 by V G

picon face
On Sat, Apr 9, 2011 at 11:14 PM, Al Shinn <EraseMEalshinnspam_OUTspamTakeThisOuTmindspring.com> wrote:

{Quote hidden}

Thanks so much!

2011\04\10@044004 by RussellMc

face picon face
Have your DC as ripple free as possible.

It's claimed that AC on the supply produces thermal cycling which can
shorten life considerably.
I'd have thought that AC at a >> frequency than the device's thermal
time  constant should be no great problem,  but it's claimed that it
is. YMMV.


        R.

2011\04\10@193353 by RussellMc

face picon face
I said:

> Have your DC as ripple free as possible.

> It's claimed that AC on the supply produces thermal cycling which can
> shorten life considerably.
> I'd have thought that AC at a >> frequency than the device's thermal
> time  constant should be no great problem,  but it's claimed that it
> is. YMMV.

Ken said (offlist message):

> According to at least one major US manufacturer of Peltier devices, ripple is not a problem  - not even at 60Hz  - so any ripple at high (switchmode) frequencies is even less likely to be a problem.

Another issue is using on/off switching  for temperature control.
This would produce marked thermal cycling.
Better would (probably) be using  a DC voltage which is varied in
order to try to cause it to just balance cooling against thermal load.
Some mix of PID control is probably  appropriate. Proportional alone
may well suffice.


Russell



          Russell

2011\04\11@001543 by V G

picon face
On Sun, Apr 10, 2011 at 7:33 PM, RussellMc <apptechnzspamspam_OUTgmail.com> wrote:

> Another issue is using on/off switching  for temperature control.
> This would produce marked thermal cycling.
> Better would (probably) be using  a DC voltage which is varied in
> order to try to cause it to just balance cooling against thermal load.
> Some mix of PID control is probably  appropriate. Proportional alone
> may well suffice.
>

Thanks. I'll probably need to make some sort of a MOSFET current source
capable of driving large loads, and keep it within the Ohmic region.

Is that the way to go about it

2011\04\11@020013 by Mohit (Lists)

picon face
Some years back I did a thermometer tester using thermoelectric modules. I used modules from Melcor, now http://www.lairdtech.com/Products/Thermal-Management-Solutions/Thermoelectric-Modules/

These should help:
1. Texas Instrument Application Note SLUA202A
2. iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
I remember Dallas Maxim also has a good AN for peltiers. You could search for it.

Regards,
Mohit.




V G wrote:
{Quote hidden}

> Is that the way to go about it?

2011\04\11@035601 by Michael Watterson

face picon face
On 11/04/2011 05:15, V G wrote:
> Thanks. I'll probably need to make some sort of a MOSFET current source
> capable of driving large loads, and keep it within the Ohmic region.
>
> Is that the way to go about it?
Or switch it at fixed frequency  (25kHz to 500kHz and filter). PWM to vary power, and filter will give a variable DC.

The drain could use a high Q L/C tuned to repetition frequency.

2011\04\11@081000 by RussellMc

face picon face
Ken adds:

You definitely don't want to be using bang-bang on-off switching (or
worse  - switching between opposite polarities) in order to control
temperature.  For maximum longevity you need to be using a proper
continuously-variable drive under PID control  - and for good measure
I'd incorporate some form of rate limiting so it can't degenerate to
bang-bang mode under unforeseen circumstances.

Just checked and it's Tellurex that says unfiltered rectified 60Hz is
OK  - they even suggest using a battery charger.

Thay also produce a special range of Peltiers for applications
requiring wide temperature swings over repeated cycles (as many
biological application do).  They are presumably designed to better
withstand the effects of thermally-induced stresses  - and I note that
they say that the maximum temperature reached in the cycle is the
critical issue.  It's well worth reading their design guidelines  - as
it is for other manufacturers as well.

2011\04\11@082002 by Olin Lathrop

face picon face
V G wrote:
> Thanks. I'll probably need to make some sort of a MOSFET current
> source capable of driving large loads, and keep it within the Ohmic
> region.
>
> Is that the way to go about it?

Did you read what I wrote last week?  I went into this in some detail.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\04\11@083925 by V G

picon face
On Mon, Apr 11, 2011 at 8:20 AM, Olin Lathrop <KILLspamolin_piclistKILLspamspamembedinc.com>wrote:

>  Did you read what I wrote last week?  I went into this in some detail.
>

The following is the only reply that I had received:

You are going a bit off the deep end.  You need to go back to the basics and
{Quote hidden}

Yes, I did read it, but all I got from it is that I should use a smooth DC
source. I don't care about efficiency, since it doesn't consume much power
anyway, and it will get power from a computer power supply (12V rail or
wahtever).

And for starting purposes, since the goal is to get the drink as cool as
possible as quickly as possible, a direct, uncontrolled 12V line is
perfectly fine, with an on/off switch. But if I'm going to be controlling
the cooling power, I still did not understand exactly which way I should go
about it.

Linear regulators that can supply 6A are hard to come by, but I can get
them.

What other ways are there, short of designing your own variable voltage
high-power power supply

2011\04\11@125154 by Olin Lathrop

face picon face
V G wrote:
>> This is why Peltier coolers are usually driven by what amounts to a
>> variable
>> switching power supply, but with enough filtering to keep the total
>> ripple to a small fraction of the average output.  Anything that
>> would qualify as
>> a
>> regulated power supply for other purposes would likely be good
>> enough.
>
> Yes, I did read it, but all I got from it is that I should use a
> smooth DC source. I don't care about efficiency, since it doesn't
> consume much power anyway, and it will get power from a computer
> power supply (12V rail or wahtever).

You better check what your computer power supply 12V output is rated for.
Peltier coolers use quite high currents, which could easily be more than a
common computer power supply 12V output is rated for.  If you just want to
drive the Peltier at 12V, then a car battery charger would be better than a
computer power supply.

Even if you don't care about efficiency, you still have to consider how to
get rid of the heat caused by the inefficiency.  Sometimes a more efficient
solution is simpler and cheaper because of that.

> And for starting purposes, since the goal is to get the drink as cool
> as possible as quickly as possible, a direct, uncontrolled 12V line is
> perfectly fine, with an on/off switch.

If that's all you want, then go for it.  You will very likely need a fan
blowing on the hot side of the Peltier though.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\04\11@133611 by Herbert Graf

picon face
On Mon, 2011-04-11 at 08:39 -0400, V G wrote:
> And for starting purposes, since the goal is to get the drink as cool as
> possible as quickly as possible, a direct, uncontrolled 12V line is
> perfectly fine, with an on/off switch. But if I'm going to be controlling
> the cooling power, I still did not understand exactly which way I should go
> about it.
>
> Linear regulators that can supply 6A are hard to come by, but I can get
> them.
>
> What other ways are there, short of designing your own variable voltage
> high-power power supply?

Just use a thermostat. Home Despot has some really cheap ones that you
can probably kludge a solution out of.

TTYL

2011\04\11@133946 by antoniasse

flavicon
face
PWM will be fine..

Luis F.



{Quote hidden}

> -

2011\04\11@134310 by V G

picon face
On Mon, Apr 11, 2011 at 1:39 PM, antoniasse <RemoveMEantoniasseTakeThisOuTspambraile.com.br>wrote:

> PWM will be fine..
>

Out of curiosity, why do you say that? It has been said that this leads to
inefficiency and greater heat dissipation in the element when there's "that
much" line ripple

2011\04\11@134514 by Herbert Graf

picon face
On Mon, 2011-04-11 at 14:39 -0300, antoniasse wrote:
> PWM will be fine..
>
> Luis F.

But why go that complicated?

The op wants a temperature control and doesn't care about efficiency, so
just run the Peltier at 12V until you reach the temp, and then turn it
on again every time the temp rises a bit.

This is a not a new problem, pretty much everybody's house has a little
device that solves this problem.

Building a circuit may be a way to learn about something new, but if he
just wants the job done a mechanical thermostat is the way to go IMHO.

Just salvage one from an old fridge if you want, then it's free.

TTYL

2011\04\11@134706 by Herbert Graf

picon face
On Mon, 2011-04-11 at 13:42 -0400, V G wrote:
> On Mon, Apr 11, 2011 at 1:39 PM, antoniasse <spamBeGoneantoniassespamBeGonespambraile.com.br>wrote:
>
> > PWM will be fine..
> >
>
> Out of curiosity, why do you say that? It has been said that this leads to
> inefficiency and greater heat dissipation in the element when there's "that
> much" line ripple.

Because you said efficiency doesn't matter.

Yes, at say 50% PWM into the Peltier will produce more heat and be less
efficient then if you ran it at 6V, but who cares? Run it at 7V and be
done with it.

Or go with the solution I mentioned, your circuit will contain just one
additional element, very simple.

TTYL

2011\04\11@144233 by Olin Lathrop

face picon face
antoniasse wrote:
> PWM will be fine..

For some value of "fine" perhaps.  PWM is not such a great way to control
Peltier coolers.  As I said before, running a Peltier cooler at 50% duty
cycle full on takes significantly more power than running it at the DC
current required to get the same cooling power.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\04\11@145245 by Olin Lathrop

face picon face
V G wrote:
>> PWM will be fine..
>
> Out of curiosity, why do you say that?

The guy who said this isn't a expert like Eric Clapton at guitar playing, so
here's a good case for assuming the advice is stupid until proven otherwise..

Using PWM in your situation makes no sense.  You have already said you don't
care about efficiency (although I'm not convinced yet you understand the
full implications including getting rid of much extra heat).  PWM is just
another form of full-on / full-off control, which Peltiers will be
inefficient at.  If you're going to do that, then you might as well use a
simple thermostat switch.  That will result in the same inefficiency but be
a lot simpler and easier to build.  You said this is for keeping your drink
cold, so a few degrees fluctuation is going to be fine.  After all, that's
how your refridgerator works too.

So in short, using PWM for this application is a dumb idea.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\04\11@154544 by k c

picon face
Olin Lathrop wrote:
>After all, that's
> how your refridgerator works too.
>
> So in short, using PWM for this application is a dumb idea.
>

Yes, in NE of NA one rarely experiences too hot environment around the
working place. So, normally, the drinks don't need to be cooled,
except for Smirnoff that best to be kept in a  refrigerator, not
around the working place :-)

NOM (no offense meant

2011\04\11@165209 by Michael Watterson

face picon face
On 11/04/2011 19:42, Olin Lathrop wrote:
> For some value of "fine" perhaps.  PWM is not such a great way to control
> Peltier coolers.  As I said before, running a Peltier cooler at 50% duty
> cycle full on takes significantly more power than running it at the DC
> current required to get the same cooling power.

Presumably with suitable LC low pass filter you will get DC enough for it?

Too high frequency and FET losses rise and too low and the coils are too big

Lower capacitance (usually lower current) Fet can go maybe 400kHz to 1MHz. Bigger FETs 20kHz to 60KHz.

Or Car battery charger and parallel LM317s with small equalising resistors as DC regulator

2011\04\11@200332 by Spehro Pefhany

picon face
At 02:00 AM 4/11/2011, you wrote:
>Some years back I did a thermometer tester using thermoelectric modules.
>I used modules from Melcor, now
>http://www.lairdtech.com/Products/Thermal-Management-Solutions/Thermoelectric-Modules/
>
>These should help:
>1. Texas Instrument Application Note SLUA202A
>2. http://iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf

Solarwind:-
I know Bill Sloman from long ago .. if you need a copy of his paper, feel
free to e-mail me.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
TakeThisOuTspeffEraseMEspamspam_OUTinterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

2011\04\11@220229 by RussellMc

face picon face
> The op wants a temperature control and doesn't care about efficiency, so
> just run the Peltier at 12V until you reach the temp, and then turn it
> on again every time the temp rises a bit.

While intuitively OKish, this is bad in practice.
It will produce the desired cooling result, but this thermally cycles
the Peltier device and leads to substantial lifetime reduction due to
thermal stresses .

PWM (also mentioned) is notionally less efficient, as also mentioned.
Add a series inductor and a catch diode and you have a buck regulator
(or an RL filter depending on where you are looking in from) with
goodish efficiency compared to optimum.

Even mild and/or partial insulation of cup from ambient will greatly
aid coolth availability.


2011\04\11@224329 by Mike

picon face
Hamilton Beach sells a wine bottle cooler using this technology. It costs about $70 US. It has a 12 vdc external power supply rated at 7 amps. I looked at the inside and there was a large heat sink and fan. Might be worth buying and dissecting!!

Sent from my iPhone

On Apr 11, 2011, at 10:01 PM, RussellMc <RemoveMEapptechnzspamTakeThisOuTgmail.com> wrote:

{Quote hidden}

> -

2011\04\11@234930 by Bob Blick

face
flavicon
face
> > > PWM will be fine..
> > >
> >
> > Out of curiosity, why do you say that? It has been said that this leads to
> > inefficiency and greater heat dissipation in the element when there's "that
> > much" line ripple.
>
> Because you said efficiency doesn't matter.
>
> Yes, at say 50% PWM into the Peltier will produce more heat and be less
> efficient then if you ran it at 6V, but who cares? Run it at 7V and be
> done with it.
>
> Or go with the solution I mentioned, your circuit will contain just one
> additional element, very simple.

Over the years I have used a lot of Peltiers and you can do whatever you
want to them if you can accept the consequences.

So if it is a low-performance situation, or if you have tons of cooling
available on the hot side, you can use bang-bang thermostats.
If you want to operate with a large temperature differential or get good
efficiency, you need smooth (ripple <10 percent) variable DC.

Forget raw PWM, if you are going that far then add an inductor and
capacitor and make it DC.

Also if you intend to do only proportional control, don't expect it to
be very good because the Peltier has a voltage drop that is related to
the differential temperature. So do full PID or at least PI. And monitor
current rather than duty cycle if you want linear control.

Cheerful regards,

Bob

-- http://www.fastmail.fm - Faster than the air-speed velocity of an
                         unladen european swallow

2011\04\12@002427 by Bob Blick

face
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BTW, peak current is not something to ignore without regard for the
potential consequence. With 127 elements in a 12 volt device you have
254 connections and it's only as good as the crappiest one. So when you
turn this thing on with 12 volts and no temperature differential,
current flow is huge and you get fewer cycles before it goes
pear-shaped.

And furthermore, for long life, keep epoxy or heatsink compound,
actually anything, from contacting the working bits of the Peltier
device.

Cheers,

Bob


On Mon, 11 Apr 2011 20:49 -0700, "Bob Blick" wrote:

{Quote hidden}

-- http://www.fastmail.fm - Faster than the air-speed velocity of an
                         unladen european swallow

2011\04\12@002901 by V G

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On Tue, Apr 12, 2011 at 12:24 AM, Bob Blick <bobblickEraseMEspam.....ftml.net> wrote:

> BTW, peak current is not something to ignore without regard for the
> potential consequence. With 127 elements in a 12 volt device you have
> 254 connections and it's only as good as the crappiest one. So when you
> turn this thing on with 12 volts and no temperature differential,
> current flow is huge and you get fewer cycles before it goes
> pear-shaped.
>
> And furthermore, for long life, keep epoxy or heatsink compound,
> actually anything, from contacting the working bits of the Peltier
> device.
>
> Cheers,
>

Thanks for the advice. I got mine for $3, including shipping, so this one
will be for testing purposes

2011\04\12@024656 by k c

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V G wrote:
> I don't care about efficiency, since it doesn't
> consume much power anyway, and it will get power from a computer
> power supply (12V rail or wahtever).

You can use a relay to switch between 3.3V, 5 V, 12V outputs when
doing PID. To cool a drink quickly you would use 12V, to maintain the
temperature you would switch between 0V - 3.3V

2011\04\12@073106 by k c

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>
> You can use a relay to switch between 3.3V, 5 V, 12V outputs when
> doing PID. To cool a drink quickly you would use 12V, to maintain the
> temperature you would switch between 0V - 3.3V.
>

The PSU can be US$50
www.coolermaster.com/product.php?product_id=6700&category_id=3570
DC output:
+3.3V     24A
+5V       15A
+12V      35A (420W

2011\04\15@025808 by cdb

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:: . http://iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf

Twenty quid just to see the article???

Colin
--
cdb, EraseMEcolinspambtech-online.co.uk on 15/04/2011
Web presence: http://www.btech-online.co.uk   Hosted by:  http://www.justhost.com.au
 

2011\04\15@030911 by Richard Prosser

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On 15 April 2011 18:58, cdb <RemoveMEcolinEraseMEspamEraseMEbtech-online.co.uk> wrote:
>
>
> :: . http://iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
>
> Twenty quid just to see the article???
>
> Colin
> --
> cdb, RemoveMEcolinspam_OUTspamKILLspambtech-online.co.uk on 15/04/2011
>
> Web presence: http://www.btech-online.co.uk
>
> Hosted by:  http://www.justhost.com.au


But at least there are "No Additional Delivery Charges" !!

RP

2011\04\15@075940 by alan.b.pearce

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> :: . iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
>
> Twenty quid just to see the article???
>
> Colin

Downloaded just fine for free, for me, from that link.
-- Scanned by iCritical.

2011\04\15@080620 by V G

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Really? I'm not able to access it.

On Friday, April 15, 2011,  <RemoveMEalan.b.pearceTakeThisOuTspamspamstfc.ac.uk> wrote:
>> :: . iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
>>
>> Twenty quid just to see the article???
>>
>> Colin
>
> Downloaded just fine for free, for me, from that link.
> --
> Scanned by iCritical.
>
>

2011\04\15@081733 by Spehro Pefhany

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At 02:58 AM 4/15/2011, you wrote:


>:: . http://iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
>
>Twenty quid just to see the article???
>
>Colin

As with most peer-reviewed journals. If you have a subscription (at a
University or whatever) then it may come down automagically. That's why
I offered the OP a copy..

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
EraseMEspeffspamspamspamBeGoneinterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

2011\04\15@083429 by alan.b.pearce

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> >:: . iopscience.iop.org/0957-0233/7/11/015/pdf/e61113.pdf
> >
> >Twenty quid just to see the article???
> >
> >Colin
>
> As with most peer-reviewed journals. If you have a subscription (at a
> University or whatever) then it may come down automagically. That's why
> I offered the OP a copy..
>
> Best regards,

Hmm, my address is .ac.uk, which may be why I could download it.
-- Scanned by iCritical.

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