Temperature changing device

J

Jadran

Guest
Hi,

my son wants to do a science project about testing heat/cold
perception using some kind of a thermal probe (I guess it would be a
peltier electrode). He found an article which describes that the
device should give a temp. range from 5 C to 50 C, should enable
steady increase/decrease of the temp. from the middle point (ca. 30 C)
and the temp. should rise 1 C/sek. I read that Peltier electrodes /or
thermodes/ could do the job but I do not know what else should I get
to assemble such a device. Could it be possible to hook it up to a
notebook computer in order to control the temp. rise/decrease?

Could anyone suggest a circuit/system which would do that (as much
details as possible would be appreciated since I am no electronics
genius).


Thanx for any help you could give me.

Jadran
 
Jadran wrote:
Hi,

my son wants to do a science project about testing heat/cold
perception using some kind of a thermal probe (I guess it would be a
peltier electrode). He found an article which describes that the
device should give a temp. range from 5 C to 50 C, should enable
steady increase/decrease of the temp. from the middle point (ca. 30 C)
and the temp. should rise 1 C/sek. I read that Peltier electrodes /or
thermodes/ could do the job but I do not know what else should I get
to assemble such a device. Could it be possible to hook it up to a
notebook computer in order to control the temp. rise/decrease?

Could anyone suggest a circuit/system which would do that (as much
details as possible would be appreciated since I am no electronics
genius).


Thanx for any help you could give me.

Jadran
Click to expand...
Peltier devices are marketed as picnic coolers and coolers for
computer CPUs. Depending on where you live and how many you want,
you might find disassembling a picnic cooler expedient. Already has
the heat sink and fan.

Depdending on how big you want the surface and how variable the load is,
you might find the most difficult part to be the controller that gives
you the controllable linear ramp. Thermal time constants being what
they are, you might have to do some predicting and nonlinear controlling.

Thought this was you son's project???? ;-)
mike

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Hi Mike,

thanx for the fast reply. Yup, you are right this is my son's
project. :)
He thought this would be a great idea (saw in TV some hot shot from
Yale talking about it).
Isn`t there a way to measure the temp. in a computer somehow (the CPU
knows how hot it is)? Could one use these circles to measure the temp
of the peltier element?

As I read more about it - it seems to me that it should be doable with
pretty simple means (cooler idea is good). But the biggest question is
how do I control the temperature. Any other ideas?

Jadran


mike <spamme0@juno.com> wrote in message news:<4140BC22.1010607@juno.com>...
Jadran wrote:
Hi,

my son wants to do a science project about testing heat/cold
perception using some kind of a thermal probe (I guess it would be a
peltier electrode). He found an article which describes that the
device should give a temp. range from 5 C to 50 C, should enable
steady increase/decrease of the temp. from the middle point (ca. 30 C)
and the temp. should rise 1 C/sek. I read that Peltier electrodes /or
thermodes/ could do the job but I do not know what else should I get
to assemble such a device. Could it be possible to hook it up to a
notebook computer in order to control the temp. rise/decrease?

Could anyone suggest a circuit/system which would do that (as much
details as possible would be appreciated since I am no electronics
genius).


Thanx for any help you could give me.

Jadran

Peltier devices are marketed as picnic coolers and coolers for
computer CPUs. Depending on where you live and how many you want,
you might find disassembling a picnic cooler expedient. Already has
the heat sink and fan.

Depdending on how big you want the surface and how variable the load is,
you might find the most difficult part to be the controller that gives
you the controllable linear ramp. Thermal time constants being what
they are, you might have to do some predicting and nonlinear controlling.

Thought this was you son's project???? ;-)
mike
Click to expand...
 
"Jadran" <njivice@gmx.de> wrote in message
news:ccad39b.0409092106.3582ee7e@posting.google.com...
Hi Mike,

thanx for the fast reply. Yup, you are right this is my son's
project. :)
He thought this would be a great idea (saw in TV some hot shot from
Yale talking about it).
Isn`t there a way to measure the temp. in a computer somehow (the CPU
knows how hot it is)? Could one use these circles to measure the temp
of the peltier element?

As I read more about it - it seems to me that it should be doable with
pretty simple means (cooler idea is good). But the biggest question is
how do I control the temperature. Any other ideas?
Click to expand...
You buy a thermistor that's 100k ohms or thereabouts. If you use a more
common 10k thermistor you might get better results if you connect
several in series. Then you connect the thermistor across the pins of
the game port that go to one of the potentiometers in the joystick.
These two pots are about 100k ohms. Then all you need is some software
to read the game port. You chould be able to do it with quickbasic,
etc.


Jadran

mike <spamme0@juno.com> wrote in message
news:<4140BC22.1010607@juno.com>...
Jadran wrote:
Hi,

my son wants to do a science project about testing heat/cold
perception using some kind of a thermal probe (I guess it would be
a
peltier electrode). He found an article which describes that the
device should give a temp. range from 5 C to 50 C, should enable
steady increase/decrease of the temp. from the middle point (ca.
30 C)
and the temp. should rise 1 C/sek. I read that Peltier electrodes
/or
thermodes/ could do the job but I do not know what else should I
get
to assemble such a device. Could it be possible to hook it up to a
notebook computer in order to control the temp. rise/decrease?

Could anyone suggest a circuit/system which would do that (as much
details as possible would be appreciated since I am no electronics
genius).


Thanx for any help you could give me.

Jadran

Peltier devices are marketed as picnic coolers and coolers for
computer CPUs. Depending on where you live and how many you want,
you might find disassembling a picnic cooler expedient. Already has
the heat sink and fan.

Depdending on how big you want the surface and how variable the load
is,
you might find the most difficult part to be the controller that
gives
you the controllable linear ramp. Thermal time constants being what
they are, you might have to do some predicting and nonlinear
controlling.

Thought this was you son's project???? ;-)
mike
Click to expand...
 
njivice@gmx.de (Jadran) wrote in message news:<ccad39b.0409091210.67941b0b@posting.google.com>...
Hi,

my son wants to do a science project about testing heat/cold
perception using some kind of a thermal probe (I guess it would be a
peltier electrode). He found an article which describes that the
device should give a temp. range from 5 C to 50 C, should enable
steady increase/decrease of the temp. from the middle point (ca. 30 C)
and the temp. should rise 1 C/sek. I read that Peltier electrodes /or
thermodes/ could do the job but I do not know what else should I get
to assemble such a device. Could it be possible to hook it up to a
notebook computer in order to control the temp. rise/decrease?

Could anyone suggest a circuit/system which would do that (as much
details as possible would be appreciated since I am no electronics
genius).


Thanx for any help you could give me.

Jadran
Click to expand...
Sounds like an unusual and interesting project.
I'll give it a go.
I did a quick experiment with a peltier effect device that I had in
my draw. It looks like it should be feasible.
Temperature measurement is not a difficult thing to do. You would use
this measurement to control the current to the peltier device and more
importantly the direction of the current. In this way it should be
possible to control the temperature both above and below ambient
(ambient in this case would be around 37C, body temperature).
I guess the probe would be a small plate, perhaps 3-4cm square, onto
which the subject would place their hand (or any other part of their
body they felt inclined to experiment on).
It is relatively easy to show the probe temperature on a standard
PC/laptop through a simple parallel port interface and also allow the
experimenter to control the temperature from the PC. This will be more
of a programming exercise rather than an electronics one. I'm not a
programmer, although I might be able to manage something in BASIC.
I will post diagrams, etc at:
http://notrocketscience.mysite.wanadoo-members.co.uk/ as an when I
have them.
Robert
 
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