Peltier on a voltage regulator, TO BE or NOT TO BE

[Demon]

Peltier musings:

I'm looking at ways to cool a LR1084 and tempted to try a tiny peltier sandwich on the front and back of a TO220 VR. I found this guy; 10mmx10mm peltier, TEC1-00703 rated 0.85V 3A:
https://www.aliexpress.com/item/1005007689267535.html

So far I see 2 challenges:

1. Getting a very low voltage power source. The common design I'm seeing is using diodes, but there are comments that they introduce "noise" from the constant clipping action.

...my go-to idea would be to PWM a logic-level MOSFET to get the low voltage.

2. Reducing the current, I don't plan on using the peltier at 100% (3A). According to the datasheet, lowering the voltage brings down the current consumption. I'd just need a source of very low voltage that could "possibly" supply up to 1A (off the top of my head, maybe I need more, maybe I need less).

3. Getting a reliable thermal adhesive since I can't use the screw, and that chinesium thermal tape looks like crap (unless a 3M product from a known supplier is worth it).

4. Learning to count.

Has anyone played with these yet?

[richard]

i would suggest a google of Peltier efficiency before you go down that dead end path. you don't see Peltier's used to cool anything that is above ambient temp for good reasons.
you would need to apply 3w to a typical Peltier device to get 2w of cooling heat transfer that means you now have 5w of heat to dissipate.
The device you linked could never cope with the heat you need to dissipate either.

[amgen]

you have easier options..... 5 volt, 5 amps
-

[Ioannis]

Forget peltier.

What are you going to do with the extra heat that peltier will generate? You obviously will need a massive heatsink with fans to get rid of that heat, outside of your case. You can't do that within your enclosure for obvious reasons. Too complicated, too expensive, bad efficiency.

Things are simple. Do not complicate it.

Use either something like the above power supply of a reputable brand, or use bigger aluminum heatsinks. Or design your own SMPS for better control of the quality of the design.

Ioannis

[amgen]

This is an electronic intervention here for you!.....

[Demon]

Duly noted.

Forget about peltier.

[richard]

if you don't want excessive heat and or high voltage AC in your box

https://www.pololu.com/category/136/voltage-regulators

[Ioannis]

Nice regulators with wide input voltage, up to 50Volts. But salty priced too.

Ioannis

[Demon]

if you don't want excessive heat and or high voltage AC in your box
...

Very nice unit:
https://www.pololu.com/product/4091

But $24.95USD for a single unit is steep. Even at 100, it's still $19.43.

That SIC471 IC goes for $7.67CAD at Digikey:
https://www.digikey.ca/en/products/d...T1-GE3/9556545

Gonna look at google for a nice schematic; it might be worth getting a batch done at JLCPCB...

Those larger power suppliers for LED applications look like they could use a fan since I'd need to enclose it. That's gonna be too big and bulky.


EDIT: Have to reread Ioannis' post in another thread. I remember him sharing 2 designs.

EDIT SOME MORE: Found it:
https://www.picbasic.co.uk/forum/sho...544#post156544

[richard]

why do need such a vast amount of 5v regulated current ?
led strips and other hungry things can be run from pre-regulated power ie 12v at much lower current for the same power.
things like the pots that need very little current but zero ripple can run from a ldo 3.3v reg , that reg can also supply vref to pic adc
design of high freq smps pcbs , especially ones that are efficient and don't get hot and cook themselves is a big rabbit hole to go down.
chinesium supplies are much cheaper but specs are always sketchy, and long term resupply is never guaranteed.

[Ioannis]

The SIC471 is much cheaper at Mouser. But this chip is difficult to solder on pcb without skills or equipment.

The TPS that was posted earlier is much easier to handle even with just the tools we all have and is much much cheaper.

But as Richard also noted, there are many other ways to do it, rearranging the needs.

Ioannis

[Demon]

A lot of this is more than just "my project", I'm often taking detours to fill in that humungous gap from not having any formal electronic education. I tend to remember things more by doing, than just reading.

I don't NEED 5A yet, I just tend to over-design stuff so that I'm never pushing stuff. Right now I'm probably using 1.5A at the most (I haven't powered 3 LED strips simultaneously yet).

I also am designing the power circuit for future use. I intend to make consoles for many more planes, each more complex and power hungry (servos, relays, etc).

I'm essentially following the capacitor voltage rating rule; a rating 2-3 times higher. (3 x 1.5A = 4.5A)

And yeah, I might just power the "logic" direct off USB.

[Ioannis]

I'm essentially following the capacitor voltage rating rule; a rating 2-3 times higher. (3 x 1.5A = 4.5A)

And yeah, I might just power the "logic" direct off USB.

Designing for one-off its OK to do that. But for production is not efficient (economically speaking). But then again, its your money.

If you paln to add later other features, just make model 2, model 3 to cover the added specs.

Sell some basic models, get the money to make a bigger model with bells then on the third add whistles too!

Ioannis