Im being thick Variable Resistor to Rheostat

[sofaspud]

You can take a PC molex adapter and mod it to output 7v as the lines on the psu allow this. Google it'll show you loads.

No, no, I'll take your word. My 5V works fine thank you. If'n it ain't broke...
Maybe your controller needs 12V minimum and your 5+ amps worth of fan is dropping the voltage output. Have you monitored the input to the controller?
The 555 and FET circuit I mentioned could have been built, cased and installed in the time we've been discussing this.

[Pjalchemist]

Originally Posted by sofaspud

No, no, I'll take your word. My 5V works fine thank you. If'n it ain't broke...
Maybe your controller needs 12V minimum and your 5+ amps worth of fan is dropping the voltage output. Have you monitored the input to the controller?
The 555 and FET circuit I mentioned could have been built, cased and installed in the time we've been discussing this.

11.75V input control set to min

11.51V input control set to max

1.01V output set to min

11.45V out put set to max

Around 10.86V the grinding stops and all fans spin

I've no idea where even begine with a 555, FET and such hense why i bought this off ebay

[sofaspud]

Apologies, but none of the measurements make any sense to me.
Measure the wires you use to power the fans. No controller, no fans, nothing but the wires (that's 1).
Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

Oh yeah. Do tell what is the input control?

[Pjalchemist]

Each wire? So each wire per fan? Input is just a 25K varible resistor as shown in the ebay link

[Boofers]

Hi. If you want your fans to just have two modes, full and quiet, you could just use a switch. In switch position 1 the fans are all in parallel, giving 12V per fan. For switch position 2 the fans will get about 6V each. I say "about" 6V each because some fans will hog a bit more current than others, but it will be close to half of 12. Just an idea. FYI the switch is a DPDT.

[sofaspud]

Each wire? So each wire per fan?

Maybe I should have written,"Measure the wires you use to power the controller" (that's 1).
Don't think 8, think 1.

[Pjalchemist]

Power from PSU to input of controler is 12.08V

What do i need to measure netxt?

[sofaspud]

Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

What do you have connected to the white 3-pin header near the electrolytic caps?

[wakibaki]

Wire them all in parallel to the positive supply and the drain of a large MOSFET, wire the source to ground, wire a 10k resistor from the 12V to a 10k pot, wire the other side of the pot to ground and wire the wiper to the gate. You have to be aware that the FET will dissipate ~20W worst case, so you need some heatsinking.

w

[Pjalchemist]

Originally Posted by sofaspud

Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

What do you have connected to the white 3-pin header near the electrolytic caps?

Measure the same wire i did for the volage feeding the controller? IE 12V input

(2) Control knob all the way to the minimum 12.02v

(3) Control knob all the way to maximum 11.38v

When turning to max it dips to 11.26v these rises to the above

A100K Verable Resistor - It came with the kit