"my Fridge" - Peltier Heating/cooling Unit

[tk75]

I have one of those "My Fridge" peltier cooling /heating units(scored from work) but it is not operational. I have pulled it down and discovered the peltier is sitting atop a big, what looks like an aluminium block, connected to the inverter/PS board. I have a pic which I will upload shortly but was wondering in the meantime if anyone may be familiar with the internals of these units and be able to offer some insight into what this 'aluminium' block is??

I intend to use it for my starters, even if I can't get it going again it will still be good for holding a constant temp at least.

 

[NickB]

I would imagine the aluminum block would be a heatsink - basically it's there so that the heat drawn from inside the unit is disipated across a large surface area.

Cheers

 

[tk75]

I would imagine the aluminum block would be a heatsink - basically it's there so that the heat drawn from inside the unit is disipated across a large surface area.

Cheers

I had considered it may be a heatsink but was wondering why it is connected to the inverter/PS unit, then I thought "Oh, ok it must be something to do with the temp. controller" so I'm really just after confirmation from someone that is familiar with these units.

 

[technocat]

G,day Maltaddict

To put it simply a Peltier Device is an electronic device with a number of P-N junctions that resides between two metal plates.
When you pass an electric current one way through the P-N junctions one of the plates will get very much colder than the other, reverse the current and the opposite happens and the junctions will emit heat. The plate of the Peltier device is thermally bonded to the aluminium block that acts like a heat sink. Special considerations have to to be given to the power supply as these devices can be destroyed through thermal shock due to rapid temperature changes.

 

[tk75]

G,day Maltaddict

To put it simply a Peltier Device is an electronic device with a number of P-N junctions that resides between two metal plates.
When you pass an electric current one way through the P-N junctions one of the plates will get very much colder than the other, reverse the current and the opposite happens and the junctions will emit heat. The plate of the Peltier device is thermally bonded to the aluminium block that acts like a heat sink. Special considerations have to to be given to the power supply as these devices can be destroyed through thermal shock due to rapid temperature changes.

Howdy Beernut,

Being an electronics tech. I do know the function of peltier devices and I'm not being patronising and thanks for the explanation as some others reading this may find it new/useful knowledge to them...just after confirmation on the temp. controller function.
:icon_cheers:

 

[technocat]

No worries Maltaddict. BTW what area of electronics are you in.

Cheers

 

[tk75]

No worries Maltaddict. BTW what area of electronics are you in.

Cheers

The area I specialised in was digital but haven't worked as a tech for many years...I got my cert., used to repair and install car audio in my early 20's and the odd service on tv's/vcr's/etc. for friend's, family, etc. then went off on a whole different avenue...so not a practising tech. just my own hobby stuff now.
Now in the liquor industry... :icon_drunk:

 

[technocat]

Yes the financial returns from a career in the liquor industry probably would have been much better than the electronics industry. Like many I ended up in management after a service career.

:icon_cheers:

 

[LethalCorpse]

Howdy Beernut,

Being an electronics tech. I do know the function of peltier devices and I'm not being patronising and thanks for the explanation as some others reading this may find it new/useful knowledge to them...just after confirmation on the temp. controller function.
:icon_cheers:

Then what's your question exactly? If you know how they work, because you're a self-professed electronics tech, then there shouldn't be any question. As nickb said, the aluminium block is a heatsink, it's there to dissipate the area over which heat is dispersed (or drawn in on the cold side). You haven't said how it's connected to the PCB. If it's thermally connected, that's so that the heatsink cools the mosfets etc driving the peltier. If it's electrically connected with a thermocouple or a thermistor, then it's so that the temp controller knows what the temperature is. Post up a pic if you like, but that's what it's doing.

 

[altone]

Then what's your question exactly? If you know how they work, because you're a self-professed electronics tech, then there shouldn't be any question. As nickb said, the aluminium block is a heatsink, it's there to dissipate the area over which heat is dispersed (or drawn in on the cold side). You haven't said how it's connected to the PCB. If it's thermally connected, that's so that the heatsink cools the mosfets etc driving the peltier. If it's electrically connected with a thermocouple or a thermistor, then it's so that the temp controller knows what the temperature is. Post up a pic if you like, but that's what it's doing.

I was wondering the same, as they're pretty simple devices - I'm not an electronics wiz, though in days gone by I did build my own
amps and other gear.

Lots of links if you google peltier device.

Just to add a bit of content, my summer ale temp controlled system is based around a Fridgemate for control, a dead fridge for insulation
and a solar powered peltier device (from a damaged portable cooler) to cool the fridge down.
I thought this would work nicely as the harder the sun beats down, the more power I get to cool the wort.
An alarm gel cell is used for power storage.

 

[seravitae]

The heatsink may be attached to both the peltier and the inverter board as the inverter board may produce heat too, so it may be a 'shared' heatsink. Also, there may be a thermistor located on the inverter PCB which is used as a safety cutoff if the heatsink gets too hot (inverter senses this and cuts power).

It's also possible to regulate temperature this way, by knowing properties of the insulation, the heat created by the inverter psu attached to the block, and the extra heat generated by the peltier, as to what the temperature is in the fridge, and thus can be used to regulate it.

 

[tk75]

Here is the pic of the aluminum block...

 

[LethalCorpse]

Those things are called thermostats. You've never seen one in your career as an electronics tech? Anyway, they're switches that cut the power when the temperature reaches a set level. One of them is a normally closed, and switches open when the temperature goes above whatever maximum they decided to use during heating. The other is normally open, and switches closed when the temperature goes above whatever minimum they decided to use when cooling. They are a pretty good candidate for having failed. You can test them by measuring continuity with a multimeter as you push it against metal vessels containing ice water or hot water. If you figure out that one or other of them is faulty, you could replace them with a temperature controller, just an on/off digital set thermostat will do. If you figure out that they're both good, the problem is somewhere else in the system. If you can't fix it, the simplest system would be one of the aforementioned digital thermostats and an old computer power supply for the 12V rail.

 

[technocat]

You've never seen one in your career as an electronics tech?

Well they were a pretty rare animal in equipment that came across my bench in 25 years of servicing.

<_<