The problem

Well here's my problem: I'm not very good at designing electrial devices/mods and i
want to build a fancontroller.

A simple fancontroller i can design but this one aignt so simple i would say :/

The fan controller

A potentiometer that controls the fan and 3 LEDs that indicates what voltage the
fan is running on. 0 = no leds on, 0-5 green LED on, 5-7 yellow LED on, 7-12 Red LED on.
If voltage at 5 then green and yellow LEDs on etc etc.

Also maybe instead of the 0-5 etc function the fan will always run on 0, 5, 7 and 12
depending on the voltagelevel. if only 2 on potentiometer then 5 output to the fan.

Well anyone seen any mod like this with "how to" or anyone with time to make a schematic? ;D

Cheers // Jeb

The dude who could do that is Twizted. He makes and sells about the same thing, but it is for a hard drive. Check out the review here:
http://reviews.pcapex.com/modding/dr...ragonmeter.php

The variable voltage input lights up different LED's.

it would probably be better to buy some DPST switches and just have 2 settings and an off. That way you can have a quiet setting (5 or 7v) and a performance setting(12v). Using this type of setup you could also buy 3-4 multi-colored LED's (one's that change color depending which circut is on) instead of the whole bunch you would need with your current idea.

i got a better idea, let him MAKE his own!

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I have that same diagram....

just throwing ideas out there, I didn't tell him to do it that way.

I appreciate that the former schematic should work alright for the intended use, but, couldn't you do it using just 3 transistors and 3 switching diodes (I can't recall the specific name)? I may be wrong, but I think that's all that's needed.

you would be correct CRE if you look at the text in the diagram it says that you can have up to 10 and to have less there is a wire that you can change to meet the requirement for your personal use!

Quote: Originally Posted by Ryj it would probably be better to buy some DPST switches and just have 2 settings and an off. That way you can have a quiet setting (5 or 7v) and a performance setting(12v). Using this type of setup you could also buy 3-4 multi-colored LED's (one's that change color depending which circut is on) instead of the whole bunch you would need with your current idea.

hmm yeah this seems to be the best idea...didn't think this would be so hard =/ Well
thanks anyway ppl :]

you could use a varible voltage regulator like most designs then the output would also go to some zener diodes to work the LEDs at the specific voltages. you could even use a bicolor (red and green = off, green yellow, red)
with a zener you put the thing in reverse (blocking) and at its designed voltage it will breakdown and conduct. i forget what that rateing is called.
addition: you could also use a comparator for the LEDs. basicly the LM339. ill see if i can make a schematic for you that you just throw on the output of any fan controller as long as it varies the voltage and isnot PWM

edit - my bad i accidently made this thing inverted as in at 12 volts no leds lit and at zero all are lit. to fix that simply switch the inputs to pins 5,7,9 and 11 and the refernces to 4,6,8, and 10. ill try to get up another example useing trim pots.

well i tried the best i could. it works but you will have to do the math yourself to find the proper values for R1-R4 and RL is just the proper resistor for current limiting of the LEDs. i think i just used 560 ohm for that.
the thing about R1-R4 which gets complicated and it would be easier to calculate having a seperate voltage divider for each voltage instead of cascading it like i tried.
with the pin outs you have 4 comparators built in so you dont nessisarily have to use the ones i chose.
i tested it out by building it and it does work but you will have to find the proper resistor values or subsitute individual dividers or possibly even just trim pots so you can choose any voltages you want.
sorry i hand drew the schematic. it was quicker than makeing it in the layout software.

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The absolute simplest way would be to use 3 resistors with increasing values on each LED.

Choose a value for each that will illuminate the LED at the specific voltage. Although this will drain more current from the PSU, but not much.

You could also use an LM3914,3915 or 3916. They are designed as a VU meter and they do away with nearly all external components. All that would be needed is the chip, LED's and 1 resistor. It can have up to 10 LED's in bar or dot mode,but you could use only 3,leaving out the ones inbetween voltage points.

Quote: Originally Posted by carbongraphite well i tried the best i could. it works but you will have to do the math yourself to find the proper values for R1-R4 and RL is just the proper resistor for current limiting of the LEDs. i think i just used 560 ohm for that. the thing about R1-R4 which gets complicated and it would be easier to calculate having a seperate voltage divider for each voltage instead of cascading it like i tried. with the pin outs you have 4 comparators built in so you dont nessisarily have to use the ones i chose. i tested it out by building it and it does work but you will have to find the proper resistor values or subsitute individual dividers or possibly even just trim pots so you can choose any voltages you want. sorry i hand drew the schematic. it was quicker than makeing it in the layout software.

Thanks man!!! Yeah i think I can do that by myself =) Will post the finished schematics later this year
(and won't forget to credit you ;] ) currently i'm just gathering data for a project at school.

Well many thanks! Cheers // Jeb

here we go with pots and 4 LEDs
i hand drew the thing again since it again is faster. i did it in pen so its even sloppier.
as long as the supply voltage doesnt change by alot during operation (which it shouldnt) it works like its supposed to.
set the pots to the voltage you want and the formula for voltage divider is
Vout = Vsupply ( R2 / R1+R2 ) so if i used a 50 ohm pot and want to get 7 volts at the slider with 12 volt supply, never mind.
have fun with it.

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ohh ty once again =)

Cheers // Jeb