Power buffer for SCAB Fan controller?


New member
Hi, does anybody know what maximum current the SCAB is capable of supplying to each fan?
By the looks of the board, nowhere near enough for my fans..
I have a 120mm delta fan, which recently blew one of the power transistors on my Akasa fan controller, and also two more 80mm deltas which make the remaining two transistors too hot to touch.

Does anyone know of a fan buffer board that I could use to boost the current output? (while retutning the tachometer signal from the fan)

The 120mm fan needs 3A at full power.

Cheers for any help.
~ Jim
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CF Tech

The limiting factor on the SCAB is the current flowing through the floppy cable connector. As you load it up, you will notice it getting warm. We use some high-performance FETs which are rated at over 4 Amps each, but you will probably run into other problems before that.

We test with 4 pieces of high-performance Delta 120s, but only for a short time. For a longer time with that much current draw, things (like the connector) will start getting too hot.

Bottom line: give it a try and post back here with what happens. Pay special attention to any heat generated where the floppy power connector mates with the SCAB. If things go south, we will make it right.


New member
Thanks for your prompt response! :)

I actually haven't bought one of these yet, but I am planning to when I buy my new PC case, amongst other upgrades.
The idea is to be able to monitor and control my fans from software automatically in the background under Linux, while displaying the currently playing track in amaroK or XMMS in the LCD screen, using the buttons on the panel to change track / volume.

I just wanted to make sure that it would be compatible with my rather power-hungry fans, since the FETs on the board in the picture looked WAY too small to power them. (The component that blew up on my current fan controller is at least 10 times the size of those things)
Though apparently size doesn't matter anymore. ^_^

I don't think the overall power will be a problem really, since the case I am planning to get will probably cause me to ditch the two 80mm deltas, and just power the 120mm delta plus three far more tame fans using the SCAB.

Thanks again for all your help. I am upgrading the PC in February, so I'll post back here when its all set up.

~ Jim


New member
I'm interested in connecting 4 Delta AFB1212VHE 120mm fans to my SCAB. They draw .9A each. the fans will need to run 24/7 as they will be cooling a server. Has anyone had any experience running high current through the SCAB for an extended period of time?



CF Tech

I think the SCAB itself will be OK if there is some air movement around it. The floppy drive connector is the limiting factor, it will get a bit warm at 3.6 amps. In real life, the fans probably do not draw th full 0.9 all the time. I think that might be a "worst case" draw.

Keep in mind that the PWM turns the fan on and off several times a second. On the big, high torque fans like you have that will put a lot of mechanical and electrical stress on them. For long life, I would recommend that you keep the power setting above the 50%-60% range. In this range, the fan is still spinning pretty quickly when the next PWM pulse hits, and the stresses are smaller--approaching the stress of normal normal operation. At 100%, and 0% there is no PWM at all, so at those speeds you will not have PWM related issues. I definitely would not recommend running them at low PWM (say 10%). at that power setting, the fan is essentially trying to do a "start from dead stop" (which is the greatest stress) several times a second.


New member
I am running a pair of 120mm fans spliced in parallel with each other off a single fan connecter on my old CFA633's SCAB. They have always performed beautifully from between about 15% up to 100% fan power in CrystalControl (1 & 2), and they are a few years old now and have run almost continually all this time cooling the radiator for my watercooling rig.

They are Sunon KD1212PM81-6A 12v DC 6.8w fans. I worked them out to be about 0.56A each, so 1.12A in total.