If you want a fan, why not buy a whole assembled fan? There are 10mm and 15mm fans available.
this post was submitted on 16 Nov 2023
9 points (100.0% liked)
Ask Electronics
3322 readers
1 users here now
For questions about component-level electronic circuits, tools and equipment.
Rules
1: Be nice.
2: Be on-topic (eg: Electronic, not electrical).
3: No commercial stuff, buying, selling or valuations.
4: Be safe.
founded 1 year ago
MODERATORS
Im surprised they make fans this small but i think they are really weak. Im gonna order one of them to test the airflow but i wanted to make my own one to fit more fan in a package thats good for my light. But thanks anyway im gonna try some of these. If the performance is really bad, a custom built one probably wouldnt be much better.
Try searching for "coreless motor", gives me lots of ebay results with tiny 7mm diameter dc motors looking like this: https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Ftse1.mm.bing.net%2Fth%3Fid%3DOIP.0qbVZk69iUxzXpp-87VHFwHaHa%26pid%3DApi&f=1&ipt=34626bb8832b480226ede8e0a44a8013a56d9217b7cb576ec699024a06297899&ipo=images
These seem pretty weak but they are cheap so i may try them if i find some from a good source. Thanks you.
These are the smallest fans that I know of: https://www.mouser.com/new/sunon/sunon-mighty-mini-fan/
They go down to 9mm x 9mm x 3mm.
If this is to cool some component in the flashlight, have you considered a heatsink instead?
These seem good and mouser has ip58 ones which are perfect for me. Maybe ill use two of them for example. But im ordering a few because if they dont work im gonna abandon the fan idea. Still cool fans. As for heatsinks the whole flashlight is one. Its a really high power, small flashlight(hotrod). It uses two 14500 lithium cells(basically aa size) to power a boost converter with more than 70 watts. Even tho the boost converter is really efficient the leds produce so much heat that the light overheats in seconds. So thats why i want to test if fans help.
Can we see this flashlight when all is said and done?
Yeah but its still months from completion. I want to machine it from aluminium but im explorimg all possibilites before i start ordering parts/writing software. When i learn to use github im gonna upload all the files with a permissive license because i want to contribute to the flashlight community.
In seconds? Wow. I think you're right, you might need more than a small fan!
It might be worth exploring heat pipes or peltier effect coolers. The latter makes the problem worse (they are inefficient and generate a lot of heat) but your LED can be locally cooler if you can e.g. move all that extra heat into a big heatsink (also condensation can be problematic).
One cheap source of heat pipes for testing could be old graphics cards -- they often outperform simple copper heat sinks. Use thermal epoxy to stick your LED to it and see if the performance is acceptable. On the exotic end of things, you could also water/oil cool it, or (carefully) make your own thermal grease from industrial diamond powder for a small boost in thermal conductivity.
Also even at 95% efficiency, it sounds like your boost converter has some heat to dump too!
Yeah the problem is the light makes so much heat(the boost as well) that i cant dump it into the air with high enough efficiency. The bodys going to be aluminium and the pcb copper.
Hm, that reminds me! If you're designing your own PCB, some manufacturers will make the PCB out of aluminum for you instead of FR4. This is commonly used for high-intensity LED lights to help keep them cool.
Here's some random info about them so you can see what I mean:
https://www.pcbgogo.com/Article/An_Introduction_to_Aluminum_PCBs_by_PCBGOGO.html
An alternative would be copper-clad polyimide adhered to the body. That also has better thermal properties than FR4.
I was already planning to use a copper core pcb. This is pretty common among insanely powerfull lights. The flashlight community has some great examples. But most of these lights use resistor based voltage regulators which waste a lot of energy in the form of heat so im trying to improve on the traditional design.
That sounds even better!
Soooo turns out mouser had a classical unit conversion error so they wrote 28 times as much airflow than there actually is in the fan specs so im not going to use fans in my flashlight as 2 watts of cooling matters so little that if i just use convection it would cool more.
Hah! I totally didn't notice that. Good catch.
Are we talking a handheld flashlight? Or is it something a bit more hefty?
Reason I'm asking is the bearings in the fan and motors. A handheld flashlight is going to take a beating, and the bearings can easily be knocked out of alignment.
Its a handheld flashlight.