Muliple Peltier elements: parallel or series?

On a sunny day (Thu, 19 Jul 2012 14:31:35 -0500) it happened Jon Elson wrote in :

Calculating for 200 C, with my 'th' program, I get the following voltages for the different themocouples:

Panteltje (c) th-0.5 thermocouple voltage (in mV) to temperature and reverse calculator. Usage: th -a [E|J|K|R|S|T] [-d] [-h] [-m C|K|F] -v voltage || -t temperature

-a type thermocouple type, either E, J, K, R, S, or T.

-c temperature cold junction temperature in units as described with -m.

-d debug mode, prints functions and arguments, and some variables.

-h help, this help.

-m mode temperature mode for temperature to voltage, either C, K, or F for Celsius, Kelvin, or Fahrenheit.

-v voltage voltage in mV, for voltage to temperature conversion.

-t temperature temperature.

Type K: panteltje: ~/compile/pantel/gpspc # th -a K -c 25 -m C -t 200 voltage is 7.138231 mV

Type E: panteltje: ~/compile/pantel/gpspc # th -a E -c 25 -m C -t 200 voltage is 11.926184 mV

Type J: panteltje: ~/compile/pantel/gpspc # th -a J -c 25 -m C -t 200 voltage is 9.501458 mV

Type R: panteltje: ~/compile/pantel/gpspc # th -a R -c 25 -m C -t 200 voltage is 1.328004 mV

Type S: panteltje: ~/compile/pantel/gpspc # th -a S -c 25 -m C -t 200 voltage is 1.298185 mV

Type T: panteltje: ~/compile/pantel/gpspc # th -a T -c 25 -m C -t 200 voltage is 8.296125 mV

So looks like a type E gives the most You can buy a pack of 5 of type E at omega for abut 14 UKP:

That makes 5 x 12 = 60 mV Should run a JFET oscillator. I have use 200 C as example, candle flame is much hotter, these small themocouples do not interfere with the visibility of the flame I think. I uses 200 as I solder some togetehr myself (not type E), and the solder melts at 200...

The 'th' (Linux) program is available from me.

Hey. Microsoft made a loss for the firt time this year, wonder when Ba;lmer get lynched... and it will be bought by 'investors', broken up, renamed, burried...

Fun fun fun :-)

Pretty clever really, you can see why I was confused. I had even designed a temperature controller with a thermocouple input by then. But I was not used to thinking of them generating amps!

Trouble is I had already done a candle powered heat engine and then a more sophisticated coffee cup powered rotary motion one in previous years. I was trying to find yet another candle based demo for Xmas.

My back of the envelope suggests that for a candle flame delta-T of

I presume the boiler thermostat is a big bunch in series. A pair of those would provide enough power capture with a bit of luck. How big are they?

I did try messing about with iron and copper wire too, but it didn't look good and produced a miniscule voltage for the amount of effort. Whoever said 160 reliable thermocouple wire junctions in a candle flame is "doable" is something of an optimist. I got fed up at about a dozen.

I didn't know about these gas boiler thermopile contraptions.

No, just one junction. It provides enough current to *hold* a low-voltage solenoid valve open against a spring, but you need to manually hold the valve open - usually a button - until the pilot flame has heated the thermocouple. This may take a minute.

I had a boiler once where the pilot kept going out and needed relighting. It was an 'instant heat' boiler which only turned on the main burners when a hot water tap was turned on. Eventually I got around to taking a look and discovered a 2" layer of dead wasps inside. Seems they'd been attracted in from a nearby nest by the warmth of the pilot flame, then incinerated as someone turned on a tap. Over and over again for many weeks, occasionally snuffing out the pilot flame on their way.

Cheers

Seems to be entirely wrong order of magnitude here - at least in the UK these gas thermocouples seem to provide about 30mV in a flame. Though apparently at sufficient current to pull in some kind of solenoid.

A pair or more would generate enough voltage to run a step up. This might be more satisfactory for demo than flat plates over the flame.

Well, in that case, make a padded bear-trap gizmo that's triggered by someone sticking their finger into a hole. Connect it to a string that's connected to a generator that charges up a capacitor, with the capacitor powering some LEDs. Set the bear trap up so that after the string is pulled out a foot or so, it releases.

Set up the thing so that once the finger in question triggers the bear trap, a candle flame is brought to bear directly on the finger.

Voila! An LED lighter that's powered by candle flame and gullibility. Not only does it have the advantage of being unique, but you won't have to worry about thinking of something next year, because you won't be invited back.

und

ting

along

=A0If you

ss

ger,

va very

nection

nes, so

around

rack.

lder the

(Solder

an

ion,

ets are

gns.

ne that

rmal.

ce I

le

t -18C

safety

he end.

~100W

modest

be any

d heat

is for

..

f hype,

..

early

-3

as a kid.

got beat

my dad was still in school then so I wouldn't know :p

-Lasse

Well, I've only picked at a BAD one, and it was quite burned up after years of exposure to the pilot flame. But, it couldn't have had more than a couple of junctions in a coaxial arrangement. I tend to think it really was just a single junction. I'll try to find details. But, maybe the voltage produced is way lower than what I suggested.

Jon

El jueves, 19 de julio de 2012, 6:57:11 (UTC-5), Richard Rasker escribi? ?:

ium

er

s:

to

and to think im a total newbie who stubled upon this trhead while looking f or a correct way of conecting 2 peltier modules using an xbox 360 power sup ply a 1209 temp control and pc parts for an upgrade to an old black and dec ker BNA17B peliter cooler....

god i love internet!!!!

On Thursday, May 21, 2020 at 4:53:28 PM UTC+10, snipped-for-privacy@gmail.com wrote :

ium

are

inium

or

tter

rds:

t 2

t to

nal

for a correct way of conecting 2 peltier modules using an xbox 360 power s upply a 1209 temp control and pc parts for an upgrade to an old black and d ecker BNA17B peliter cooler....

If you e-mail me at snipped-for-privacy@ieee.org I'll send you a reprint of my pape r on the subject.

Sloman A.W., Buggs P., Molloy J., and Stewart D. ?A microcontroller

-based driver to stabilise the temperature of an optical stage to 1mK in th e range 4C to 38C, using a Peltier heat pump and a thermistor sensor? ? Measurement Science and Technology, 7 1653-64 (1996)

It hasn't been cited all that recently - nothing since 2018 - so there may be something better around.

It covers the theory, if not in any great detail - there's only so much tha t you can squeeze into ten pages.

Welcome. You're accessing this group using the Google Groups WWW interface, but in fact this is a Usenet newsgroup, sci.electronics.design.

Usenet started in 1979, and covered the whole world within a couple of years, at least for folks that had Internet access at that time. It was and is based on the NNTP protocol, rather than HTTP/HTTPS.

That makes it a decade older than the World Wide Web, and 19 years older than Google. It's the original social media platform, and has virtually none of the censorship problems associated with the Big Tech-dominated platforms. If you dislike somebody's posts super badly, you don't try to get them banned, you just set a filter so you don't see them. Democracy and freedom, right?

Some groups, such as this one, include folks with world-class expertise. C'mon and join the fun!

You can view Usenet with Google Groups, which does have a pretty deep archive of posts (*) (you would probably have had trouble replying to an eight-year-old post on Twitter, for instance). However, the best way is to get a real newsreader such as Thunderbird or Forte Agent, and an account on a free news server such as aioe.org or eternal-september.org. There are also nearly-free ones such as Giganews and Supernews, which also have deep archives, but have recently been experiencing some performance problems.

Cheers

Phil Hobbs

(*) Google bought out the original Usenet archiver, DejaNews, in 2001, and acquired both its extensive archive and its Usenet search technology.

Phil Hobbs wrote in news:ra6vu5$b82$ snipped-for-privacy@gioia.aioe.org:

You need a hot (or cold) slurry between the heat or cold source and the surface you wish to have a homogenous temperature across its surface on. First off, you cannot go to big or even local room currents will throw you off.

I used to make black body calibration source 'ovens' for IR Thermometry some decades ago, and we used a huge, 6" diameter Aluminum ingot with a single rod heater shoved about 40% of the way up its ass. The face had a concentric set of sawtooth wave grooves across it at about 1mm height, and the best damned carbon black black body high emissivity surface coating around. The outer half inch was obscured by the front aperture plate/cabinet opening, and it sits back about 30mm behind that. The surface temp homogeneity was pretty damned good for simple IR thermometry. But for a larger surface a thick slab front surface was needed and a liquid oil behind that with the homogeneous temperature to spread. So for the peltiers run them at full tilt in whatever direction you desire (hot or cold) and use that to heat or cool a vessel and pump assembly to heat the oil that lies behind the panel surface. But a huge 50 kilo block of Al thick enough to allow several backside heat/cold sources to soak through enough thickness of media to homogenize the temperature on the front side surface works good too.

That array would all have to be individually managed and calibrated in, likely for each big set point jump. OR put a nice sloshy oil chamber between them and let it soak into the front mass evenly.

The surface has to be recessed back into the cabinet it is in as room air currents mess it up, and IR imaging devices don't like calibrating from 'bad' surfaces.

We used to calibrate Optical tube, resistor bolometer thermometry devices with it from a 1" focus to my 4" gold mirrored, 1.5 foot long tubed, rifle scope aimed, rifle stock fitted IR thermometer with about a 50' focus that electrical linesmen used to look at insulators and transformers for overheating and leakage from the ground. Now we just use IR imagery. Did not have that back in '86, without HUGE bucks and LN handy. So we sold a lot to the power company guys. Cool thermometer too.

I probably built this one...