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FrozenGate by Avery

TEC Basics - Do they need to be driven?

Curious - with TECs that have metal sides instead of ceramic ones, is the metal completely electrically insulated from the TEC internals?

IE, suppose I was making a labby, and wanted my aluminum Aixiz mount to be electrically isolated from the labby base (aluminum), would putting a KasEO projector's TEC (with copper metal sides) in between the two, accomplish electrical isolation?
 





Yes.
All TEC's have ceramic walls as part of the core structure around the PN-junctions.
The copper comes ontop of that and is mostly used as heat-spreader and protection as the ceramic is brittle against point-contact and uneven pressure.
 
Careful with this point .....

TECs that have a single piece of copper layer on the sides, are electrically insulated, but if you found one of the old high-current models that was used in first fridges, and that have a lot of small rectangular pieces of copper, that form their sides, they are NOT enectrically insulated, and you need to use Kapton or silpads or mica sheets, for use them.

Anyway, is relatively difficult to find around these old high-current TEC plates, actually ..... they was an old model, more "brittle" (can break more easily if bended or pressed in the wrong way) than the modern ones. so they are disappearing.
 
Basically, TEC's can be run without driver, as long as you supply the required voltage. However, you might run into difficulties carrying that heat away. Also, they don't like ripple. So it's always better to use a driver. A simple DDL can do to just limit the current so it doesn't run at max power and your kitchen sink *erm* heatsink can handle it. If you want precise temperature stabilization, then you might wanna look into "real" TEC drivers with thermistor feedback. A quick Google search for "TEC controller schematic" or "TEC driver schematic" brings up couple of results.Basically, TEC's can be run without driver, as long as you supply the required voltage. However, you might run into difficulties carrying that heat away. Also, they don't like ripple. So it's always better to use a driver. A simple DDL can do to just limit the current so it doesn't run at max power and your kitchen sink *erm* heatsink can handle it. If you want precise temperature stabilization, then you might wanna look into "real" TEC drivers with thermistor feedback. A quick Google search for "TEC controller schematic" or "TEC driver schematic" brings up couple of results. This thread on PL is a good source of drivers. BTW, are you looking to cool a diode to 5°C? :)

A simple drawing of a TEC taken from some datasheet:
 
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HIMNL9 said:
Careful with this point .....

TECs that have a single piece of copper layer on the sides, are electrically insulated, but if you found one of the old high-current models that was used in first fridges, and that have a lot of small rectangular pieces of copper, that form their sides, they are NOT enectrically insulated, and you need to use Kapton or silpads or mica sheets, for use them.

Anyway, is relatively difficult to find around these old high-current TEC plates, actually ..... they was an old model, more "brittle" (can break more easily if bended or pressed in the wrong way) than the modern ones. so they are disappearing.
Click to expand...

You are absolutely right, they do exist. Technically though, they do not have a side-wall on the copper pads side. That is the bare interconnects of the PN junctions that are exposed. They are usually small tabs of copper or similar. You are right though that they are not electrically insulated but anyone looking at them would immediately see that they are not.
 
My driver is up and running. It uses a Tiny10 and a buck-converter circuit comprising of a coil, diode and fet. To drive it I use a bootstrapped opto as I have a bag of em and they have nice push/pull setup.
By reading ambient and cold side as well as a user adjustable input I can regulate to any delta around/below ambient. I did it this way to go a tad below ambient, but not more than 5-10c to avoid dew.

Once firmware is a tad more stable I'll post a thread with full drawings and source.
 
Very cool madmacmo!
Mine doesn't have a display as I wanted to try the tiny10, but that is mostly due to me wanting it to be relative to ambient and as cheap as possible.

I have been running it for almost a month now with hours of use almost every day and so far it works well. A bit of adjustment is still needed on the code but considering I am working around the bugs in the ATtiny10 c-compiler it's working quite well.
I'll post a BOM later this weekend so you guys can find the cost of parts.
 
They say max current of 1A per "fan." I wonder if you can connect them in parallel to drive a 40W TEC. Even if you couldn't, a power transistor should work for control. I'll pick up a pair.

edit: ouch - shipping is $17.16 for two... bought from ebay instead.
 
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Johnyz said:
Basically, TEC's can be run without driver, as long as you supply the required voltage. However, you might run into difficulties carrying that heat away. Also, they don't like ripple. So it's always better to use a driver. A simple DDL can do to just limit the current so it doesn't run at max power and your kitchen sink *erm* heatsink can handle it. If you want precise temperature stabilization, then you might wanna look into "real" TEC drivers with thermistor feedback...
Click to expand...

Just realized that I wrote that two times. wat.
 
I'm definately interesped too, but I too don't ahve a lot of free time, so maybe somewhere in the hopefully not too distant future I'll have a good laser diode test bench. My test equipment (PSU's, multimeters, power meters, scopes etc) are all hooked up via GPIB, so I'm getting there.
 
Does anyone know of an affordable source for TECs in the 10 to 18mm (length and width) range?
 
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