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Simple TEC driver?

ReNNo

ReNNo

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I plan to make my own TEC driver and want to make it as cheap as possible.
If there are some TEC experts I'd like to hear what is the cheapest way to make driver.
 





depends do you want a temp controlled driver?
you can use a lm317 to drive your tec.
but if you want to have temp control i think you best bet might be the incorporation of a pic and a temp sensor.
there might be a way to use a thermistor instead of a pic or micro controller but not 100% sure.
more details would be very helpful
 
kiyoukan said:
depends do you want a temp controlled driver?
you can use a lm317 to drive your tec.
but if you want to have temp control i think you best bet might be the incorporation of a pic.
there might be a way to use a thermistor instead of a pic or micro controller but not 100% sure.
more details would be very helpful
Click to expand...

A TEC (depending on size) will pull more current than a LM317 can handle. You'll end up smoking it.

My 30x40mm TEC easily pulls 10A at 12V at full power. Thats 120W.
 
TEC that I want to use can work up to 6A.
Lm317, even Lm350 is not solution.

Also... I need to know what power supply to use. Maybe cheap PSU from computers?

For beginning I don't need TEC driver that is temperature controlled, I only need to set it to desired current.

But if there is easy way to make temperature regulated TEC driver I can pay few buck more and build it.

@Seoul_lasers
Nice find, but It looks pretty expensive to buy all these components.
Can I buy this driver directly from this guy, and how much will it cost? (If you know something about that)
 
Last edited:
well for lasers unless you have a burning hot laser driving a tech at its full power will damage the laser and case many problems of freezing.
i would say try a lm317 out and see if it gives enough power then if you need more cooling power go for the LM338T
up to 5a.
LM338 - 5 Amp Adjustable Regulator
also this if you want some crazy power
LM723C - Voltage Regulator
But to be honest i doubt you will need to drive that tech at 5a to cool the laser.
you want to keep them cool and not cold.
and i think the driver is around 26 euros give or take a few.
 
One more problem about voltage regulator is voltage drop.
This TEC works on 12V (I think that is nominal voltage).
If I use computer PSU that gives 12V then output voltage will be lower...

26E is too much for just playing with TECs.
I don't plan to use TEC for any special use.
For beginning I'm going to use TEC for cooling laser diodes (445nm).
Temperature doesn't have to be accurate ... these diodes can work from 0-30C.

Only what I want to do is to make temperature lower than ambient temperature and to keep temperature under 20C.
 
if you drive the LM338 at 12 volts,
the voltage will drop down to around 11 but even at 11 volts and 5a it will be super cooled at that power.
 
Use a 555 with a mosfet for drive it PWM, and a thermistor for change the duty-cycle ..... i think this is the more simple way .....
 
I googled and I found this:


The LM338 has a drop out of 3V which means it requires a difference of 3 V between the input and output to regulate properly. When it's configured as a current regulator, the sense resistor between the output and the adjust pin will drop another 1.25V at full load. 3+1.25 = 4.25V.
Click to expand...

That is too much voltage drop and I don't know how TEC will work on that low voltage.
 
TECs are not as sensitive components as laser diodes are.
However, a bit more complicated drivers with multiple outputs exist in professional laser systems, they also incorporate MCU controlled temperature, in 473nm lasers, LBO crystal is anything but temperature-ignorant.

However, since I don't think you gonna be colling LBO crystals, any applied power to it will help keep the temperature of your components down.

Keep in mind however, that TEC as a components is not thermally conductive, means that if you mount the diode on it without TEC powered, it's worse than just simply mounting the diode on a heatsink - if the TEC would be thermally conductive, it would have a hard time keeping the cold side - cold.

IIRC, TECs are around 20% efficient - hence, calculate the temperature dissipation of your laser diode - for blue diode driven @1A, it'll be around 3.2-3.5W of heat - and set your TEC accordingly, 5x more power consumption, so it'll provide aproximately needed cooling power.

Maybe I'm wrong about some facts, though...

Gawd I wish I had some MCU programmer boards, I'd be making temp-controlled laser systems...
Why are the programmer boards so damn expensive? :thinking:
 
kiyoukan said:
thats would be interesting can you bring up a schematic for it?
Click to expand...

Sorry for the delay ..... i had already posted this one, times ago, but i lost the link, so i had to search it again.

3058-tec-driver-01.jpg


I used this schematic, for drive a TEC with a 555, and at the same time give it a "feedback" from the cold side, for keep the temperature stabilized ..... it's not a professional thermometer, just the more easy way that i've found for do it :p :D
 
Thanks HIMNL9.
That looks very easy and cheap to make.... and very effective for my purpose.

How much current can I push trough that circuit?
Do I need 12V power supply?
About resistors...do they need to be high power ones?
Can you give me more information about temperature sensor and about this BC337 transistor...does it have to be in larger package for better heat dissipation?
 
ReNNo said:
Thanks HIMNL9.
That looks very easy and cheap to make.... and very effective for my purpose.

How much current can I push trough that circuit?
Do I need 12V power supply?
About resistors...do they need to be high power ones?
Can you give me more information about temperature sensor and about this BC337 transistor...does it have to be in larger package for better heat dissipation?
Click to expand...
If you're short of any components... ;)
 
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