So, I want to control a fan with a thermostat, what do you think of something like this? Why? - Active Cooling, naturally

Flashlight Modding and DIY Parts
1

So, I want to control a DC fan, (like a fan for a PC), with a thermostat, what do you think of something like this?

KSD 9700

I just need to determine 40C. 45C or 50C for cut in, to turn on the fan.

EDIT: 3-3-14

So, I am playing with fan cooling. Of course it would need to be on a bigger light, with room for a fan, but what about waterproof? Well, if the fan was the only thing exposed to any moisture, then it might be waterproofed, good enough at least to take exposure to some water, like out in a rain shower. So, I am playing around with an old fan I had lying around.

I cut the fan out of the housing and maybe I can seal up the circuit board, so water won't get to it. Maybe...

I have already removed the plastic washer from the shaft, so I can take off the blades.

I used regular silicone. I could have used fujik, but I figure just for a test, this ought to work. I have sealed just around the area where the circuit board is, so water doesn't get to it. I'm not really worried about the stator wire wraps. I shouldn't need to seal it.

Once all this dries, I will put the fan back together and toss it into a bucket of water, with some batteries to power it up. If it works, I will have a plan to use, for some active cooling. If I use a 40mmx10mm fan, it might put out about 5cfm. If I go with w 40mmx20mm fan, it might get up to 8cfm. Ok, that's not a lot of air flow, but how much air flow is inside a regular flashlight? Zero, zip, nada, so a few cfm is better than nothing, isn't it.

-----------------------------------------------------------------------------------------------------------------------

So, I got the fan back together and I tested it.

I just hung it in water and left it hang, while I checked to see if it was getting any continuity across wires, which it never did, so here goes.

Works fine and I even left it in water for a half an hour or so. Good enough for me. Now I know I can seal a fan and now I can use a fan in a build. It's all I needed to know. When I do it for real, I will use Fujik most likely.

2

I can’t see any reason why it wouldn’t work but I have no experience with that one. It does seem simple enough.

But of course now I’m wondering just what you need that fan for, Hmmm. Sounds dangerous, you should send it to an expert for testing, hint hint. (lol)

3

The temp depends on your needs, but this switch is ok, 5 amps, on at 45 Celsius degrees and reset at 30 (the one linked). That is a good enough interval, if the values are very close the fan will be switching on and off all the time

4

I figure with the amount of heat, it might stay on most of the time. Probably around 150-175 watts.

5

Sorry, I can’t disclose that at the present time.

6

Is there anything else that would work, just has to be small. The fan will only draw a small amount of power, .2 amps or something like that...

7

That’s the smallest Size of thermostats I’m aware of. You can get smaller sensors, but they are not able to handle a lot of current. If you are so sure the temp will be over that values most of the time, isn’t “always on” an option?
Let’s see if anyone has a solution for your mysterious new monster flashlight problem

8

Seems like the most straightforward way.

Now I am thinking one of these at 50°C or so would be a nice switch for the cooling fan in the BT-3100 charger (to raise the temp the fan starts at), though I can only find normally-closed and I don’t want to make a logic circuit for something so small.

9

They make NO too. I saw a lot of NO with a google search Open temperature switch

10

Thanks, I found some selling in higher quantities. I will ask if they can sell just one or two.

Another idea was something like this, comes in variety of packages:

There are simpler sensors too. A LM393 comparator can be used as the switch.

The bimetal thermostat has a couple of issues, partly the tolerance, and the 30°C reset temperature.

11

Well, I broke down and put up a little more info in the OP

12

Remember the touch switch I used for the laser in the ray gun? No moving parts, just two insulated contacts close enough to be covered by one finger. Your hand is the thermostat. Adjust grip to turn on the fan. They can be set up so it’s on only when touched or touch on, touch off.

13

What ray gun?

Actually, I don't remember that part of the build, but I just want it to be automatic. That way it takes out the human equation of having to remember to turn it on.

14

it’ll work, i build few lights with t-stats, and couple of them have fans, others just trim output.
with sinkpad stars, i install t stat on the heatsink, as close to star as i possibly can, i use 70c to cut off, in some builds i use simple cut off termal switches that either dissconect power, or dissconect leds, and open led circuit, (need to have driver that is open circuit protected). other bilds have to have relays, since small (to220) t stats can only handle little current.

15

If the mystery thingy generates that much heat, why not just wire the fan into the power switch so it runs whenever the thingy is on? You don't have to remember to turn it on, no thermostat to fail. You can tell right away if the fan fails, rather than waiting for the thingy to overheat to find out. Those fans do eventually fail.

16

Something different is all and cause I can. Just something different to do.

17

Looking forward to the results!

18

Sure, there's always that. Going to have it powered all the time so the fan can run a bit after the thingy is turned off to prevent a temperature spike? Like some computer power supplies.