DIY $5 Open loop water temp thermometer w/mini LED display

pr0xZen · May 6, 2019

I already wrote this up really nice and tidy, and had a power outage. This time will be quick n' dirty.

I came across this cheap, nifty little gem for those of us who like informative mods and "tools" - and put it to work. It's a nifty little LED display with controller for 10K thermistor display. Temps in Celsius. It is really small and discreet, visible through your case window even in daylight, but no so intense as to be distracting in darkness. Can be used with any 10k thermistor probe, doesn't have to be an in-loop one.

For what I did with it, you'll need:

Mini LED display - $3 (Got mine here: AliExpress )
G1/4" Plug with 10k thermistor temperatire sensor - $2 (Got mine here: AliExpress )
Some scrap leads and heatshrink
Molex / Sata / USB / whatever adapter you can splice into for +12V and GND (aything between 4-28VDC will do)
Soldering iron and solder
Something for cutting and cleaning up a square hole in a spare PCI slot cover - dremel, file, drill etc.

Display looks like this:

Black and red power leads are way too short to be of any use for this. Desolder them, solder on scrap leads of ample length for tidy cable routing. Solder or otherwise wire other ends to +12V and GND on a molex / sata adapter, or another suitable source.

Cable length on the G1/4" thermal sensor plug is way to short - extend as you need, solder joints and heatshrink over solder joints. Install the plug in suitable location in your water loop, using a free spot or a splitter/T block.

Mark around the opening in the rear case panel, onto the PCI slot cover while it's installed.
Cut ~23x10mm hole in the cover (Due to the design of my slot covers, I had no area to drill holes for screw mounting, so made the hole precise - friction fit for the display housing). Cut between the markings you made before, to make sure no part of the hole is covered up by the rear panel of the case when installing the bracket.
Cut another hole, or a slot out towards the endge, in the slot cover for pulling the cables back into the case. If you cut a slot all the way down, it might save you some hassle routing the cable for power, as those two cables are soldered to the display PCB, not socketed. In my case I opened the space between a couple of the original holes. Some cable sleeving can be good, but optional.

Pull the cables through the slot, install slot cover, pop the display in the hole from the outside pointing in. Oh and I used a black marker to color the white sides of the display housing. Slot cover got a bit scuffed up while filing the edges of the square hole, if you're picky about that, cover it in painters tape while working on it.

Display can be had in other colors than red. Different temperature probes exist, any 10k thermistor will do (one is included with the display, fine for air temps. Listing says it's waterproof, I haven't tested that).
Due to the small size and cost, doubling up on these and having one pre, one post the waterblocks could be nifty.

Feel free to bring any questions, ideas and suggestions.

Tristerin · May 11, 2019

I this. Im preparing my second loop (did my first on an old i5 system to get the hang of it a month ago) and was wanting something just like this. And I LOVE modding, and even more - affordably. Aliexpress is where I sourced my first loop (all pieces independent, not a kit)

pr0xZen · May 11, 2019

11 hours ago, Tristerin said:

I this. Im preparing my second loop (did my first on an old i5 system to get the hang of it a month ago) and was wanting something just like this. And I LOVE modding, and even more - affordably. Aliexpress is where I sourced my first loop (all pieces independent, not a kit)

Thank you for the kind feedback.

I've always been a big fan of creative, DIY mods, and never shied away from bringing out the powertools and breadboards/protoboards. So the moment I saw this little gem, modding thought kicked into overdrive hard I now have like 6 of them lying in wait for future mods and ideas.

This has been my first custom WC loop/setup though, a perfect project for the tinkering modder. I was aiming for a pick-and-choose AliExpress loop myself, but got reeeally lucky on a couple of 2nd hand market deals, so the core components of my loop are EKWB, but I ended up around the same total cost estimate. Only significant change of design plans was going from 2x360 AliExpress rads to 240+480 EKWB rads. Took a bit of cutting to shed the optical bay cage and arrange secure mounting, but it ultimately made space for 480mm EK rad at front intake. Ample room, at least 2-3mm to spare in my Obsidian 750D! Well all core parts EKWB except for the very recent 1080ti block, which i got still sealed with my 2nd hand purchase of the GPU. Up until a few weeks ago I was running 2x980ti with EK fullcover blocks.

I do have a bunch of fittings and smaller parts from Ali though; flow indicator, 45° and 90° swivel fittings, extenders, adapters, plugs, plugs with throughholes for sensors, and valve etc. Swivel fittings were closer to $1.50 than the more typical $10-15 with eg. Bitspower. They look and feel identical to Bitspower - so I suspect these are "nightshift runs" of the same thing, B-grade sorted Bitspower fittings due to minor cosmetic defects, or really good knock-offs. I got one that was very soft and leaking, but all others were nice and tight, and at that price I did order spares. Also got a bunch of replacement O-rings as I wasn't 100% comfortable with the old seals on some of the 2nd hand parts. Also got 11.2mm drill bit, G1/4-19 threading tap and same size die, for making custom parts and fittings. Dirt cheap and very reasonable quality, just gotta educate yourself on what to look out for, and sifting through reviews to irk out the genuine ones.

Compression fittings I got most of them with the other 2nd hand EK stuff, only needed 2 extra, so I stuck with the same EK ones for that. For being "EKWB quality", EK's fittings are actually fairly cheap. At least if you buy them from EKWB directly.