PSU based non PC project.

Bloodrazor · 21 Jan 2022 at 03:59

Hi all,

I was looking for some guidance on a project I'm working on. This project is a full of gadgets terrarium / climate control housing for potentially not just tarantulas.

After struggling a lot finding components NMIC which would be properly grounded etc I realized I may as well turn to PC enthusiasts for help where community is vast and there is no shortage of parts.

I am looking to hardwire components such as PTC heating elements to work directly from a PSU (e.g. 12 V 50 Watt PTC from a SATA connector or GPU 6 or 8 pin port). This part being most likely most power-hungry element of this build.
PTC heating element will be involved in self controlled climate control system which I have planned but if component would be different I don't think it would exceed 100 Watt on a 12 V connection.

I genuinely don't feel knowledgeable in this field and starting to scratch the surface and looking for guidance on what would be the safest approach:
Do I need to build any custom boards to make it possible or is it safe enough to go straight for cables and connectors.

To answer some potential questions:
- why PSU? It has huge market of parts, converters, adapters and knowledgeable community. PSU will also provide me modularity with this project and will help avoid using of extension leads, multiple plugs etc.
- is it just PTC heating? No, some of the functions for this project will include: climate control (heating and cooling), lighting system, electronic curtains, watering system, feeders, and hopefully voice control or remote control access point to name some functions.
- do i have any PC related knowledge? I have a custom build PC and have been building PC's for quite some time (mostly for own use).
- do i have target PSU? Corsair RM550X.

I thank you all in advance for your input regardless how critical.

Blood.

Rroff · 21 Jan 2022 at 04:08

A PC PSU is normally not very efficient as a general purpose power supply and requires a certain approach and minimum load to turn it on really. You'd probably be better off with a 12V DC power supply such as those used as an LED driver (though grounding concerns/protected earth can be a consideration).

Most PC PSUs you can't just flick the switch on the back and have voltage on the rails - depending on model it will need certain pins bridged or some other signal to enable power, usually a minimum load on one or more rails to stay on. Voltage regulation or the amount of power you can pull from a rail can depend on load conditions i.e. some will not power stuff requiring 100s of watts on the 12V rails if there is insufficient loading on the 5V, etc. etc.

This is something I've gone quite far down the rabbit hole with in the past:

And is almost always the wrong way to go about it - even though there is a certain attraction to doing it that way.

Bloodrazor · 21 Jan 2022 at 05:29

Rroff said:
A PC PSU is normally not very efficient as a general purpose power supply and requires a certain approach and minimum load to turn it on really. You'd probably be better off with a 12V DC power supply such as those used as an LED driver (though grounding concerns/protected earth can be a consideration).

Most PC PSUs you can't just flick the switch on the back and have voltage on the rails - depending on model it will need certain pins bridged or some other signal to enable power, usually a minimum load on one or more rails to stay on. Voltage regulation or the amount of power you can pull from a rail can depend on load conditions i.e. some will not power stuff requiring 100s of watts on the 12V rails if there is insufficient loading on the 5V, etc. etc.

This is something I've gone quite far down the rabbit hole with in the past:

And is almost always the wrong way to go about it - even though there is a certain attraction to doing it that way.

Thank you so much. I reviewed the datasheet as far as I remember and one of the rail ( it might have been main motherboard 24pin) is capable of supplying up to 300 or 350 Watts.

In my choice I was happy with the fact of having 3, 5 and 12 (I think 9 too) volt connections. I'm not too technical with certain aspects but the picture you attached is pretty much what I would invision. I read some technical reviews and they mentioned that this power supply have some sort of low power consumption iddle and stand by so this made me a little less worried about initial start. I'm also aware about bridging two connectors to get it up and running...
The minimal consumption I was hoping to achieve with some sort mini computer for control or visual input such as temperature preview ona fancy PC controller. I'm hoping this would provide me with this minimum load...or perhaps raspberry pi which would responsible for voice control. I'm still trying to research and figure out best approach but I thought pc PSU would be my safest bet - I know they are reliable, components are NMIC, I have my grounding and stable supply of power even if low energy loads are not most efficient for this power supply (they are not...)

Is there any 12 volt power supply you had in mind or would suggest that could be turned into such device? I'd imagine it wouldn't be as bulky and heavy...

My main information on if Corsair would handle low loads came from below:
https://www.tomshardware.com/reviews/corsair-rm550x-power-supply,4484-5.html

Some tech det.:

Armageus · 21 Jan 2022 at 06:56

Bloodrazor said:
I am looking to hardwire components such as PTC heating elements to work directly from a PSU (e.g. 12 V 50 Watt PTC from a SATA connector or GPU 6 or 8 pin port) .

If you do go down this route then you want to use molex connectors rather than the Sata power connectors, as molex connectors are rated for a lot more current (Sata will be marginal and poor quality adapters etc have a habit of catching fire)

Mercenary Keyboard Warrior · 21 Jan 2022 at 15:24

Im with Rroff on this one. If the items your using can be 12v I would go down the 12v only supply route.

You can get a lot of 12v stuff as its used for CCTV, and LED but also campers and things.

Eg you can get a 12v fuse panel, sets of 12v switches and power that from a decent size 12v transformer. The transformers will normally list a min / max load. Transformers designed for LEDs often have a much lower minimum load than ones designed for other uses.
And dont have the other gubbins etc that a PSU has for overload, overcurrent and 5v rail etc that you do not need

arknor · 21 Jan 2022 at 16:43

Bloodrazor said:
My main information on if Corsair would handle low loads came from below:

according to google a pc in sleep mode draws around 12 watt

Bloodrazor · 22 Jan 2022 at 13:28

arknor said:
according to google a pc in sleep mode draws around 12 watt

PC might yes. But power supply alone will have around 1W stand by usage. I won't have active components in the quantity or power draw amount to account to 12W. At least I wouldn't expect huge increase with what I have planned for it.

Most components would be controlled and usually off / time controlled or scenario controlled with the use of a raspberry pi or similar in capabilities controller such as:
https://shop.aquacomputer.de/product_info.php?language=en&products_id=3092

I'm researching 12 V power supplies options. Thank you all for suggestions.