Another DIY Fan Controller - Adjustable Voltage Regulation 5-11v with Kickstart!

[LennyRhys]

Hey folks,

I've been away for a while (very busy with work) but I've recently found the time to play with fans again, and this time my attention has been drawn to bing's DIY 90W fan controller here.

As some of you know I like to test fans, especially powerful ones, but only some of these fans are PWM compatible which means I will need a different kind of controller for the non-PWM fans, and this is why I thought I'd give bing's 90W controller a go:

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The nice thing about this controller is that it has a kickstart feature which is especially useful for fans which will turn at 5v but won't start at 5v, and my Sunon is one of these very fans. It is also a nice feature because when you power up your system and think "WOW...LOUD" you are pleasantly surprised when the noise dies down after a few seconds or so (the more powerful fans do take quite a bit of time to slow down - see video below).

The circuit on breadboard, fully functional:

And the heart of the circuit: the LM1084 regulator

One of the fans for which this controller was built specially: a 3000rpm version of the popular Gentle Typhoon

And the Delta makes its obligatory appearance in "another" fan/fan controller thread:

VIDEO:

 

[Bobnova]

I might just have to make one of these, my delta 252cfm could use some control!

EDIT:
Looks like you lose some top speed, between 1 and 1.5v dropout through the regulator. If you want to run it full blast there isn't really a reason to use a regulator anyway though.

 

[LennyRhys]

Bob - you're spot on. Just finished filming the controller in operation and the dropout is just over 1v, the power topping out at 10.97v (iirc). I filmed each fan with the DMM set up next to it, showing the gradual drop in voltage after initial powerup and the maximum output with the pot cranked right up.

Nice controller, but very slow to respond when the pot is turned - capacitors? It takes several seconds before the voltage corresponds to what happend with the pot...

I also have a much simpler emitter-follower circuit which I will post later. It uses just a TIP31C and a 10K pot, and does a great job with low powered fans (up to 500mA) and the dropout is extremely low, like 0.5v or so. I will also make a quick vid of this when I have time.

 

[bing]

The nice thing about this controller is that it has a kickstart feature which is especially useful for fans which will turn at 5v but won't start at 5v, and my Sunon is one of these very fans. It is also a nice feature because when you power up your system and think "WOW...LOUD" you are pleasantly surprised when the noise dies down after a few seconds or so (the more powerful fans do take quite a bit of time to slow down - see video below).

Dave, about the kick start period, if its too long, you could shorten it by replacing the C1 cap 1000 uF/16V with smaller like 820uF or 560uF or 470uF or 100uF to see which fits your need.

As the original circuit, I did make a simple chart on the kick start period between two cap values, so smaller value will yield shorter kick start period, and this cap is also affecting the pot response time as you're experiencing.

Thank you for creating this thread, its been quite sometime now since the last OCfer built this circuit.

Can't wait to see the video on that kick start period, must be interesting.

If don't mind, suggesting to add the words "- With Kick Start Feature" at your thread's title, hopefully to attract more participants, the more the merrier , just ask one the mod thru to rename it.

Btw, I always envy that bad *** camera of yours, they always make me want to throw away my entry level dslr.
Really nice shots and love the one with a really shallow DOF at the LT1084 ic to emphasize it's importance, hmm... I'm learning something there today.

 

[LennyRhys]

Thanks for that explanation bing - I'll try to get some of these caps this week to see how they affect the performance of the controller.

Re. the pictures, these were taken with my 5D and Sigma 50mm f/1.4 lens, which produces really nice shallow DOF at f/1.4. Sometimes the 1DsII is just too big and heay for little snapshots like these and I can't be bothered setting it up for the photos lol

Video is uploading now, and I will keep the thread updated as regularly as I can.

Video added to first post!

 

[Seebs]

You guys suck!

I haven't even been able to put my pwm controller down on pcb yet and you come out with another circuit for me to "not be able to build properly"...



Oh well.. good thing I don't have any non PWM high speed fans yet, but when I do... You know what'll happen.. I'll put the circuit down on breadboard, get it to work and then murder about ten or fifteen pcbs while trying to put it down on permanent form.


I've been wanting some of them high speed GTs and since finding the PWM version of them seems harder than finding the Holy Grail I may have to get the three wired version of them.

 

[LennyRhys]

The non-PWM GTs are easy to get hold of and are a lot cheaper than the PWM versions, so I'd say take the plunge if you want one. The 3000rpm version is nice because it has the lowest starting voltage of roughly 4v (compared to 7v with the 5400rpm version), however the mediocre performance below 2000rpm defeats the purpose of taking it much below 7v anyway lol.

It's very easy to see the superiority of PWM fans when you test a controller like this with power-hungry fans - there is considerable voltage dropout of almost 1.5v with a heavy load (the Delta draws about 1.8A at 11v), and set at the lowest output the controller requires a lot of heat dissipation, wasting a lot of energy. I should try one of my San Ace monsters just to see what the dropout will be lol...

 

[tool_462]

Would it be feasible to make a controller with kick-start for 9 x Gentle Typhoon AP-15's? They are the 1850 RPM variety.

I have to run them a fair bit higher speed than they need to stay running, since they won't start up with less, but this would be perfect. If they were barely spinning it would be enough, I have about 3x the radiator space I need

 

[LennyRhys]

Yes it would be feasible - this controller can handle up to 5 amps, which equates to SIXTY Gentle Typhoon AP-15s.

 

[bing]

The voltage drop out is a major issue when it comes to drawing big current using this off the shelf component.

If I had the time, I will try to make a circuit design that has a really low drop-out even at high current, probably less than 0.1 volt or even lower at 5 Amp !
Hows that sound ?

But this might take a while cause I'm quite busy and currently on business traveling.

 

[tool_462]

Yes it would be feasible - this controller can handle up to 5 amps, which equates to SIXTY Gentle Typhoon AP-15s.

Well if someone can put one on to a PCB I have some money in PayPal

 

[LennyRhys]

Sounds good bing. Let me guess - you thinking of using one of the rare and expensive Micrel voltage regulators which has 200mV dropout? I thought I might buy the 3A one (MIC29302) and give it a try myself, but maybe I'll wait to see what you come up with!

@ tool_462, I'd definitely recommend building one yourself - the components are very cheap and it can be a lot of fun putting circuits together!

 

[inVain]

great project Lenny, and nice share

The voltage drop out is a major issue when it comes to drawing big current using this off the shelf component.

If I had the time, I will try to make a circuit design that has a really low drop-out even at high current, probably less than 0.1 volt or even lower at 5 Amp !
Hows that sound ?

But this might take a while cause I'm quite busy and currently on business traveling.

sounds great

recently, I've just bought an AMS1083CT . the seller told me that this IC is the replacement for the legendary LT1083
compared to LT1083, this chip is really cheap (1/10th actually)

can't find which company is manufacturing this unit, but google search lead me to this datasheet:
http://www.digchip.com/datasheets/parts/datasheet/015/AMS1083CT-30-pdf.php

8A current capabilities but still,
1.3 typical voltage droop, and 1.5v max
as for now, to the drawer it goes

 

[bing]

Sounds good bing. Let me guess - you thinking of using one of the rare and expensive Micrel voltage regulators which has 200mV dropout? I thought I might buy the 3A one (MIC29302) and give it a try myself, but maybe I'll wait to see what you come up with!

Actually that is not I'm planning to use, apart from expensive, most people will have difficulties to procure it within reasonable price.

I'm thinking using common discrete components like resistors, capacitors, an op-amp and power mosfet, which are so common and much more easier to get with cost a lot cheaper.

And for the sake of simplicity and easier to build, using non smd components, probably I will not include safety mechanism like short circuit protection and thermal shutdown. Cause by adding this features alone, the circuit's component counts could get more than 20 pieces instead of under 10 pieces, which I think is not suitable for simple diy-ers audience here. Wondering if this is acceptable compromise ?

Using certain mosfet, the voltage drop can be lower than 0.1 Volt at 3 or 4 Amp range. Heck, if the builder feels adventurous, it is possible to go even lower at sub 0.01 volt at 5 Amp.

About the high speed/power industrial fan, you're right, there is no point to buy new non pwm one once you've experienced the pwm version, unless its a very good quality fan like that GT fan, and low power maybe below 0.5 amp.

 

[Bobnova]

That sounds pretty good to me.
I've been contemplating similar things, say a atmega328 driving a nice fat mosfet a 65khz pwm with some caps and an inductor to smooth things out a bit.
I don't know enough to actually build something like that, I need to do more research.

I think that short circuit protection/OCP in the form of a self reseting fuse is probably a good idea, those are cheap and easy. Other than that just give it a big heatsink

 

[bing]

That will be quite complicated Bob, and imo its better to jump directly using switching type (buck controller/switcher) that has better efficiency (approx 75 -95%) and interface it with your mcu.

But this will be really hard for casual diy-ers, since this kind of circuit is very difficult to build them properly at breadboard level, cause the nature of power switching circuit. Also even on pcb level, the components layout and placement is very critical.

Also some components will be definitely in smd form which is quite challenging, especially without proper skill & experience, let alone the required tool like scope for troubleshooting if its not working properly, or a special soldering tool for smd sized if they're too small for normal soldering tip to handle, namely like non legged components.

Not sure, maybe I haven't look hard enough, for this kind of circuit, we need an ic called buck controller either with built-in switch or using external, but must have a capability called 100% duty cycle. Majority of the switching controllers out there don't have this feature. It is needed for a very low drop out voltage when the fan at full speed.

I guess for a simpler start up, its better to stick with linear type 1st, but with ultra low drop out capability.

 

[Bobnova]

Yeah you're right on that one, I'm mostly musing to myself regarding what I might try to make and sell, I'm starting to get vaguely OKish at SMD, sortof. I have other things to work on first though. I'll almost certainly take a crack or two at the linear LDO regulator flavor first.

Question:
If I need to control a 3.3amp fan, can I use four 1 amp LDO regulators, or will there be balancing issues?

 

[Prime]

Wow, I'm suprised it didnt knock your camera over! Great Work

 

[ziggo0]

I know this thread is a bit old & I hope you guys are still around - what modifications would have to be made to get 2 ~ 3v after the kickstart?

 

[LennyRhys]

We are always around when fan controllers are being discussed, lol Interestingly enough I recently tried to put this controller on stripboard and I have contacted bing (it's his circuit) for help with it, because unfortunately it's not working properly.

To answer your question, the resistors (including the potentiometer) are responsible for setting the voltage range. I don't know exactly what you'd need for 2-3v as there will be a specific formula for that calculation, but bing and others have the EE expertise for precisely this sort of question.