Making high power fan controllers - guide

[femtoghoti]

school takes a big bite out of my project also ... i find i have about 16 weeks of nothing followed by a flurry of activity until the next 16 week lull. as for schemes and diagrams, i am not that far into things.

to answer your question tho ... at this point i am going to need to vary the voltage between 6 and 12 volts. 6v at the bottom end was chosen to make things easier, that is open to change as the mood moves me. how i plan to implement the PWM is with a counter and a comparator. so long as the coutner is below my 'threshold' value i will hold that line low. throw that thru an AND gate and i can blank out the amount of the pulse i need. i have not thought about the comparator, but i am sure some one has an elegent solution. if they don't i can AND my threshold and counter into a T flip-flop.
i am planning on having this cycle repeat its self every 500ms.

of course using DAC's elimate all the above "funny buisness" and cut straight to the point. i looked at DAC's for doing this, but they were expensive when compared to FET's.

 

[zbarnes]

Using

I am looking for two 120mm fans to cool my dual '77 Bonne heatercore.

I have a nifty fan control thing for the thermaltake volcano cpu fan that fits in an empty floppy drive bay:

http://www.newegg.com/app/Showimage.../35-106-038-01.JPG&CurImage=35-106-038-07.jpg (the thing on the right)

You guys think I could use it in your circuit to make a speed control for 2 12v fans? (I have some electrical circuits knowledge, but plain english is my favorite way of learning)

My second question:

Model- AFB1212VHE
Dimensions- 120 X 120 X 38mm
Rated Voltage- 12 VDC
Operating Voltage Range- 4.0-13.2 VDC
Rated Current- 0.6 Amp
Rated Input Power- 7.2 Watt
Speed- 3200 RPM
Max Air Flow- 129.96 CFM
Max Air Pressure- 0.420 IN H2O
Noise- 48 dB-A

I know probably no one knows, but can anyone educatedly guess if these fans could be set so low on the voltage using a homemade speed controller that the noise would drop to the 20's dbA(albiet 30's probably more practical)? Would it still keep my computer from burning up at that low of a speed?

I want to have some super high air flow when things are hot, but then at night keep my computer running near silent.

Maybe this is more trouble than just getting some panaflo m1a's, but I can get those deltas $4 shipped! Would the performance be good, or no?

 

[Ven0m]

I'm not sure how this controller works, but if it's simple pot, you might use it probaably for transistor controller. Problems may appear if it has too low resistance (what might result in some overheating), or lacks 3rd leg, so not all controllers could be made. Eventualy you could buy some pot and use enclosure from TT controller. Without any mods, TT controller won't be able to handle dual Deltas I think and even if somehow will, it won't allow full voltage range. If you make some circuit, I guess you may play a lot with these Deltas - operating voltage starts from 4v - that's huge range.
I doubt you can make them run at 20dB, high 20s, perhaps even mid 20s, should be in range.

You could make 2-transistor controller, possibly with kickstart, calibrate it to minimum voltage they can run and I think you'd be satisfied with both controler and Deltas. Unfortunatly, I think that pot from TT controller won't be useful, adn you'd need to buy a new one and put in TT enclosure - that might be pretty useful, as you wouldn't have to make front panel. 2-transistor controller has a good property, that it's got very linear characteristics, so you could precisely choose voltage. Some bargraph display may improve functionality and look. With fans at full blast, current would be >1A, so I'd suggest not to use very thin wires. Also, notice that these controllers give some max voltage drop - around 1v, so if you want to run them at full speed, you may also think about some switch with which you could choose between voltage from controller and directly from 12v rail.

 

[zbarnes]

Well, I was not really thinking about using the Thermaltake thing on the 12v line, but as a remote control for a circuit. Like using some kind of current amp with transistors or whatever to make it an external control for an internal circuit.

Thats how it was used on the thermaltake. I am guessing the fan would send a small current through it, and however it was moddified through the knob, it would change the speed of the cpu fan that was running on a 12v line. I don't think it ran the 12 volts through it... I may be wrong however....

If this is how you'd do it, what kind of transistors am I needing, and how do I get the voltage needed for powering the transistors(this setup will be on top of my computer, but I can run wire out the back)?

Then I would just need a selector switch to switch between straight 12v and the potentiometer/transistor setup.

Pardon me if I say something stupid, I am going off of some things that I learned a year ago about current amps. I got a C in that class so.... I may say things that are way off.

Anyone think that the only thing inside that knob is a variable resistor? If so, if the values are off, I can just add some resistance either in parallel or series, depending on if it need to go up or down.

Maybe if I figure things out, I could use a bar graph too.

 

[Ven0m]

I bet you'll rather have to replace that pot that is in TT controller, if that's pot. If it's not I can hardly tell a good way to mod it, just replacing pot and making 2-transistor controller from guide. I think that schemes and some users replies will answer most of questions.

 

[zbarnes]

Sounds like a good plan, as soon as I get some time. I barely worked with transistors in my intro to circuits class, so I will be reading very carefully and may be doing some => . Those Deltas are cheap so I'll play around with them in case I burn something up. I'll let you guys know what I find out, maybe post some pics or something, just in case someone else has one just lying around collecting dust, like me.

Just put an ohmmeter on the potential potentiometer (lol) and got .005 on the low, and 9.38 on the high....

Still haven't had time to read through the guide yet, so is these kind of values what I am looking for, or will I have to switch it out?

 

[Ven0m]

Just put an ohmmeter on the potential potentiometer (lol) and got .005 on the low, and 9.38 on the high....

Still haven't had time to read through the guide yet, so is these kind of values what I am looking for, or will I have to switch it out?

Everything is in schemes. And what are these values? If these are kOhms, should be ok, if ohms - you need something that matches schemes.

 

[zbarnes]

Ya, that be kOhms, forgot to put that. I've never heard that term used before, "schemes". You mean like units?

 

[Ven0m]

Check 1st post - there are pics - schemes - showing what and how to solder.
With electric stuff you'd need to know units probably.

1 / 1.000.000.000.000 - pico (p)
1 / 1.000.000.000    - nano  (n)
1 / 1.000.000        - micro (µ)
1 / 1.000            - milli (m)
1                    - base unit
1.000                - kilo  (k)
1.000.000            - mega  (M)
1.000.000.000        - giga  (G)
1.000.000.000.000    - tera  (T)

So for example 4.7 kOhm resistor has resistance of 4700 Ohm. Capacitors capacitance is usually shown in µF - I don't recommend converting it to base units.

According to my calculations that would work. You could get up to ~11v. With greater 1st pot, you'd also need to use the 2nd one with higher resistance - you need around 4kOhm to have bottom limit of 4v in this case. So 4kOhm resistor might work, but I'd rather suggest using ~20kOhm pot - so you could adjust minimum voltage in ranges ~0 - ~6.9v. Or 50kOhm pot - to get minimum range of ~0 - ~8.2v.
To calibrate, you set primary pot to min, secondary to max, and decrease secondary resistance until fan slows down to speed you want to have as minimum. Then it's ready and with primary pot you can adjust voltage.

 

[zbarnes]

Schemes= Schematics... haha I get it. Brain dead.

Ya, sorry, I made myself seem a bit dumber than I am. I've got a year under my belt in Computer Engineering, mainly undergrad, but one circuits class.

Would this circuit be the proper setup? Would that hard switch I put in there work to short circuit the variable speed to make it go full speed?

I wa s playing around with that TT pot, and accidently hooked it parallel with a fan, man did it heat up faaast. I smelled something burning and it was the TT thing.... I'll just wait till my real fans come in and built the circuit, before I hurt my shiny new Powerstream!

Since I have two fans, how does this work into the circuit above? are they in parallel(voltage drop would be the same over both), series, or will this circuit not work with two fans?

 

[Ven0m]

2 fans should work in parallel - you can soder 2 connectors in parallel, so it wouldn't require any fan mods. Connecting fans in this way should not casue any problems.
And DON't USE THAT CIRCUIT MOD. sorry but that's some bad short-circuit wiring.
If you really need these 12v and 11v is not enough, switch should direct 12v to "red dot" over fan or "red dot" over Q2 transistor - there are some switches that have 3 pins - so middle pin would go to 12v and these on sides to these 2 points. If 11v is enough - no mods are needed.

2nd pot - if that TT pot isn't burnt yet, check my previous post about choosing proper. Ther'es also another problem - if that pot has heat up that fast... It had small resistance, that means that you need other pot. Or maybe you wired it in the way I can't simply imagine... The best would probably be using circuit as-is, just taking TT controller enclosure.

 

[zbarnes]

Ya, I see my mistake.... I was short circuiting the whole circuit. I forgot that the fan was over in the circuit. I just drew that real quick-like and wasn't paying attention. I don't know if the TT pot will handle this, so I am going to experiment when my fans show up. From the ohmmeter readings, it looks like it should though...

I had the TT pot hooked in parallel with the fan when it heated up. If I hook it up in series, it works, but the fan spins at maximum 1/4 of the speed its supposed to. I'll quit playing until I get the transistors.

I'll definatley double check things when I start building the cicuit. I have just been looking at this guide in my spare time, which is usually about 3 or 4 minutes in between studying.

Thanks for putting up with my newbish-ness.

EDIT: I didn't even need to pull out the ohmmeter, the back of the pot says 10k! hahaha
Everyone refresh your browsers... I edited that pic^

 

[Sleeper]

I just wanted to post, that I made the simple Speedfan auxiliary hi power fan controller, and am using it with a Thermaltake Smart case fan 2 on my CPU (AX-7 heatsink) and a 120mm ADDA intake fan. I run the 80mm Sunon exhaust fan off the chassis connector. I set the SpeedFan case fan speed to 30% (Slightly above he minimum to keep he TT fan running) and am playing with the case and CPU desired and warning temp settings to automatically control the temps. I set the delta value for the fan speed to 5 and the exit/startup to 100%, (so I left out the capacitor.) It works wonderfully. Any load on the CPU and the fan speed gently increases to compensate for the temp increase. At idle I can have a CPU temp of 32 deg (not too sure about this) and a case temp of 24 Ambient room temp of 22 deg with the fans idling at 30% and it is really quiet (I am cheating a bit by using CPUCool a well)
I am running an OC'd AMD Athlon 1800+ (Palomino) at 1828 Mhz. Now I'm not a gamer, so I am not really stressing the system, but it is very stable.

One question I have is when I upgraded my bios, my CPU temp reading changed. Is this lower reading correct?

Thanks
Paul

 

[Ven0m]

That's good to know that it works well.
Actually capacitor was for other purpose - with Speedfan you get PWM power control, so it's set of "there's voltage", "there's no voltage", and actual power depends on lenght of these periods. Some fans don't like it (for example all my fans but one), and capacitor would stabilize the voltage. Anyway if your fan has nothing against PWM, it's better to run without capacitor - this way you get more torque.

I've also experienced huge temp reading drop after one BIOS flashing on my A7V333, now I think that readouts are a bit too low, but still more correct than earlier.

 

[Sleeper]

Thanks again VenOm
FWIW
I had an old blown power supply sitting around, and it had all the parts I needed to make the controller. (Even the heat sink and cap) The transistor used in my PS was a Fairchild KSC5027 and has higher ratings than the BD139. (The leg configuration is slightly different though.)

Paul

 

[zbarnes]

Alright, I have to make sure I've got this right, I'm going to the electronics shop on monday. I'm going to need a circuit that can handle 2 of these 10.8W(12V*.9A) Delta VHEs (and maybe three little 92mm case fans 3W(12V*.25A)?)

Parts:

-10kOhm ThermalTake pot for the primary pot
-20kOhms secondary pot
-36W PNP Transistor from the first page
-36W NPN Transistor from the first page
-random molex connectors
-random non-wussy wires

Is this the reccommended? Or did I get something wrong? I am mostly making sure that I am supposed to get a 20kOhm pot, and 36W transistors, so let me know. If I want to be able to do those extra three case fans, will I be able to?

Thanks

 

[Shroomer]

The NPN transistor can be a very small one. Read through the thread again. I used a 2n3904.

I think you may be confusing 2 different circuits together, but I'm not sure.

 

[Ven0m]

If that TT is 10k...

Actually Shroomer has done that controller, but he found htat you don't need so powerful Q1 transistor - smaller one would last (check his posts maybe, this might result in less cash spent) - this is when you don't set main pot to -zero- resistance. If you're unsure - use big transistor, if you'd like to run a smaler one, some 10Ohm between main pot and transistor should do the job.

And I think that these "36W" transistors should actually allow up to around 60W of total fan power on rail. Also get some metal sheet for radiator or some simple heatsink. In electronics shop they should sell some, eventually you might use some smaller computer heatsink.

 

[zbarnes]

Well, I got all my parts, and I just understood what you meant, Venom, about that TT pot not having a third leg. I am not smart enough to know how to mod the circuit to get around this, since I don't even know what the third leg is. ^that is how I guessed, but I don't know if its right.

If no one knows, I guess I'll just switch out that pot in the TT.

Locally, I could find none of the recommended PNP transistors. I bought a TIP42 from radioshack with these specs:
Power: 65W
Vce: 40V
Vcb: 40V
Veb: 5V
Ic: 10A

Will this work? It may be more than needed for this circuit, but will it work anyways?

Almost forgot, what voltage rating should the capacitor be? I have lots of different rated capacitors in old junk.

 

[Ven0m]

That should run fine. This baby, if properly cooled, should be able to power a lot of fans. If I guess correctly, it could be over 100W of max fans power

Problem might appear with TT pot if it's not 3-pin...

That circuit should work, but I'd add some resistor, probably around 1kOhm, over secondary pot to be sure not to short circuit. And it should work properly. You may also consider some smaller resistor (around 10-100Ohm) on line, where you have "Is this ok", not to allow too much electricity through Q1 transistor when you set TT pot to max. I just can't tell if that's needed in this case.

And maybe I'm boring and anoying, but triple check that TT pot resistance (in both directions as perhaps it has some diode added) at minimum and maximum and make yourself sure that max is really 10k and min low.