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Anyone know where I can buy something like this?

Red Squirrel

Red Squirrel

No Lifer
Something that takes a 12 volt input, outputs 0 to 12 volts based on the temperature range of 20C to 30C (give or take) so if it's 20C it outputs 5 volts, if it's 25C it outputs 8.5V, if the temp is 30C or more it outputs 12.

Rather simple concept, but I can't find anything anywhere that can do this. If I had knowledge of electronics I could probably just make it myself. I googled it real quick and it does not look THAT hard but again the problem is finding the parts. The downside of being in Canada is the availability of "specialty" parts.

This would be used for controlling fan speeds in a custom built server. The motherboard does not have thermally controlled fans, and even if it did, I have yet to see a motherboard where that feature actually works well. It's usually like a 1v difference.
 
could just use a fan that has built in thermal control, or a fan controller that reads temps and responds accordingly. you shouild be able to find such a fan controller. they used to be very common.

in any case, it's not like 30c is even warm to a server.
 
I already have fans, if I limit myself to the few available fans that may have that feature it will make my choice limited. And 30C was just an example, maybe 40C would be more like it, but you get the idea.

Right now I have two Tornados running at full tilt in my main box. wont be a big deal once I wall in the server room and add lot of sound proofing, but right now it's kinda crazy lol.
 
Red Squirrel said:
I already have fans, if I limit myself to the few available fans that may have that feature it will make my choice limited. And 30C was just an example, maybe 40C would be more like it, but you get the idea.

Right now I have two Tornados running at full tilt in my main box. wont be a big deal once I wall in the server room and add lot of sound proofing, but right now it's kinda crazy lol.
Click to expand...

that's a lot of pr0n.

😱
 
Damn, that's a tall order, because you're asking for a scaled output across a completely adjustable range.
A 2-speed would be much easier. Wire up a thermostat so when "off" the current goes through a resistor limiting it to 5V and when "on" it bypasses the resistor.
 
maybe a LM317 Adjustable voltage regulator + a thermistor in the feedback leg would do it. i'd stick the equation in excel and fiddle with the values to line up with standard thermistor/resistor values.

edit: oh it'd never hit +12, only +12 - whatever the dropout is
 
You don't want to linearly scale between 0 and 12 volts. The fan speed is not linear with respect to voltage.

You can buy pre-made fan controllers that work very well. They're aimed at PCs. Look at the PC modding sites as well as Newegg.
 
DominionSeraph said:
Damn, that's a tall order, because you're asking for a scaled output across a completely adjustable range.
A 2-speed would be much easier. Wire up a thermostat so when "off" the current goes through a resistor limiting it to 5V and when "on" it bypasses the resistor.
Click to expand...

I was actually thinking this as well, may be easier to just do that... or even multiple thermostats, like 3 steps. IN fact I'd even accept a device that does it in multi steps, does not have to be fully linear and I don't really care so much about the exact temp/voltage as long as it's a decent range for a computer setting.

Like 0-12 may be too much. At some point a fan just wont turn at all, so probably even best to start at 5 and go up from there.

I was looking on sites like newegg.ca but there does not seem to be much.

There was this pyramid thing I could buy a while back from Sunbeam, but they don't seem to be made anymore. That's exactly what I want... though that one did not have a big enough range imo, it was probably more like 8-12v.
 
You could bias the gate of a power MOSFET to provide a smooth variable output with a few discrete components. The sensor could be a common 10k thermistor.

Of course this is not very efficient with commutator-less drive fans. Better of using PWM in the first place. 😉
 
PottedMeat said:
maybe a LM317 Adjustable voltage regulator + a thermistor in the feedback leg would do it. i'd stick the equation in excel and fiddle with the values to line up with standard thermistor/resistor values.
Click to expand...

How would you adjust the temperature range, though? A pot in parallel with the thermistor?
 
Rubycon said:
You could bias the gate of a power MOSFET to provide a smooth variable output with a few discrete components. The sensor could be a common 10k thermistor.

Of course this is not very efficient with commutator-less drive fans. Better of using PWM in the first place. 😉
Click to expand...

You can use the voltage output of the thermistor to alter the duty cycle of a PWM signal.
 
Leros said:
You can use the voltage output of the thermistor to alter the duty cycle of a PWM signal.
Click to expand...

Yes and there are a lot of fans that have this capability built into the driver.
If noise is a concern the OP could just watercool everything and run the lines to a chiller. 😀
 
DominionSeraph said:
How would you adjust the temperature range, though? A pot in parallel with the thermistor?
Click to expand...

yeah that'd work, but you could just ballpark the values of the resistor divider + thermistor combo. maybe even nonlinear too.



but yeah ^a pwm 555 + thermistor + mosfet is probably best.
 
Before clicking the thread I was totally picturing a rocket launcher, imagine my disappoint. 🙁

Leros said:
Look at the PC modding sites as well as Newegg.
Click to expand...

FrozenCPU.com or SVC.com would be much better sources for parts of this nature.
 
Rubycon said:
Yes and there are a lot of fans that have this capability built into the driver.
If noise is a concern the OP could just watercool everything and run the lines to a chiller. 😀
Click to expand...

Actually, I do plan to water chill the entire server room once it's built, so maybe I can just keep all the fans at 5v and not worry so much about variable speed, may be easier. :hmm:

Basically I'm thinking of having the server room's air pass through a filter, radiator, and then back to the room. Grab the air from the back and bring it back to the front, basically. Cold/hot isle idea. The water will then be pumped around the entire crawlspace. If I wanted to get fancy I could have some kind of temp sensor on the incoming pipe that opens a valve to go to an outside "chiller unit" (basically another rad) if it gets too warm. May as well take advantage of our average temp being below freezing. 😀

In summer I'd have an AC unit in there, though I have a feeling the water system alone would maybe be enough, it's not like I have a rack full of Dell screamers, just a couple servers and network stuff.
 
Rubycon said:
Yes and there are a lot of fans that have this capability built into the driver.
If noise is a concern the OP could just watercool everything and run the lines to a chiller. 😀
Click to expand...

Yup. What the OP wants already exists in polished form in several pre-exisitng fans and fan controllers.
 
Problem is, I rarely have spare bays when I build a server, I use them for hard drives. In my case I only have a 3.5 spare. Though guess once I go to a SAN setup, I will have spares, so I guess these type of controllers could work. They do look pretty cool.
 
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