I've been playing with my 555 pulse timers and figured I'd post what I've done so far as there really doesn't seem to be a decent schematic online anywhere.

I didn't want any potentiometers, I don't want the owners turning the fan down. Just a simple 555 timer schematic for running the fan at a decent rate.

Runs off the fans 12V Brown wire so no need to wire from another source. To regulate the pulse peek voltage to 3V I used a common LED and it also helps to visually gauge the pulse frequency.

With 4.7K ohm at R1 it is still quite fast and about as loud as a 360 12V Mod. Combining resistors to make around 5K ohms or so should quiet it down a bit more. You can change the C1 from 1uF to 10uF but then you must change the R1 value accordingly.

Ahhh, I just realized this is only good for one speed. The pulse width becomes too long at lower freq.

I've done this mod for a couple PS3 owners now and they seem happy with it.

One good thing about this is you can substitute many different value resistors and caps and still get the same ~50% fan speed. Only if the frequency gets too low you will hear the fan turn off and on. Like below 20 Hz. the frequency in the schematic is quite low, I'm told the actual fan pulse is 25Khz with 20% duty which is too slow. It is the duty (percentage of time the pulse signal is high) that really determines the fan speed.

If I can get around to it I will post a ~35-45% Mod later on that needs an extra diode and resistor but it's not a big priority for me.

If anyone had ideas to make this pulse mod even simpler, please post but remember I'm not interested in adjustable POT mods. I want a decent speed FIXED mod. Users will just turn a POT to it's lowest setting anyway. I'm not making these for myself, I don't own a PS3.

Here's my diagram for a 555 Pulse mod with around 30% fan speed / duty cycle.



As it says you could replace R1 with a combination resistor + POT in series to fine tune.

I suspect you can use probably use any Capacitor from .1 to 10uf for C1 as the actual frequency doesn't affect the fan too much. as long as it's between 30Hz and 25Khz.

Here's another diagram 50% speed without using the LED. This is how I've been doing them recently:

Boas,

gostaria de montar este esquema mas tenho duvidas quando ao 555.
Qual foi a referencia que usas-te?


Cumps

I got the idea for using the LED as a 3V pulse source from this site:

http://www.horrorseek.com/home/halloween/w...5TimerCalc.html

They were using the 555 chip to blink LED's for halloween costumes.

Also some info here:

http://www.doctronics.co.uk/555.htm


So the schematics using the LED is to reduce the 12V output to 3.3V pulse peek. The only problem with this is if the LED ever dies the Fan pulse will peak to around 10.5 volts or so and possibly damage the fan. I realized this from the beginning and decided it was an acceptable risk. The 555 chip can handle being powered at 12V and if I remember correctly the output at pin 3 is around 1.5V lower than the power voltage. The whole reason I did it like that as I wanted the whole mod attached to nothing more than the 3 fan wires, fore convenience mostly. Now if you power the 555 chip from the PSU 5V line like my last diagram there is no need for the LED to drop the voltage for the fan pulse line, the pulse output should peak at 3.5V.

you have a video showing how do this mod ? please

No vids, sorry.

I do have an install pic:



This one is the diode version. Different capacitors and diodes require different value resistors to get the speed just right when using the diode variable duty version.

After soldiering I just wrap in tape and tuck in over the fan connector.

do you have a schematic of the 30% pulse mod without the LED?

No but just power with 5V and wire pin 3 to the fan pulse wire.

guys are the pin numbers on the schematics the same as this pinout?

Yes they are the same. The reason they're not in the same layout on a schematic is becasue it makes a real mess to keep them the same as they are on the actual components, but number 1 on 555 in the schematic is the same as pin number 1 on the 555 chip and so on.

thanks RDC. Heres some pictures of my mod running with an led and no potentiometre.
I used 3x 1.8k resistors at R1 to get the level I wanted.

I did the fan mod for my PS3 slim model CECH2501A with the 50% pulse mod. Yes it is working but do not forget to put ground on the ground fan.
I have 2 questions:
1) Increasing R1 is there a limit?
2) Cutting a hole in the the top just over the fan about 1 and a half inches is it a good idea. I am not sure because air will be suck thrue that hole instead of hole around the unit to cool all parts of the unit.?

Here's another schematic. This one still uses the motherboard pulse signal combined with the 555 chip. This way you get to increase the fan speed to a decent rate but the motherboard can also increase the speed if it needs to. All this would be completely unnecessary if Sony just set the damn fans to a decent speed to begin with, but Oh no, they can't make any noise at all so they'd rather let them slowly cook to death!

Hi I was wondering.. Would it possible to just cut the grey wire? Wire nr 3 and then add a resistor to the 12v wire so that It always runs on for example 9v ? Would be hell of a lot easier because of the fact that your method is a bit over my league and that I can't find the right materials in my country

You'd need at least a 10 watt resistor if it even worked at all.

i'm a noob here ho can't read a schematic , can you help me with a real pic of this 50%fan mod with no led..
thnks alot dude..



what kind of capasitor can i use ? polar or non polar ? whih one is + which one is -? HELP

Doesn't matter what kind of cap, both work, pretty much anything under 10uf seems to work. - Neg is going to Pin 1 (ground).

I pulled the adjustable duty schematics. Do not use them, they will most likely have your PS3 running too hot!

USING A RATE LOWER THAN 45% WITH NO MOTHERBOARD CONTROL IS NOT RECOMMENDED !!!!

I discovered fats, especially backward comparable run hotter than I expected!!!

I recommend use the 50% mod and live with the sound.

Have you noticed any change in your method when the system is running 4.0 FW? I used to mod the fan by taking the 3.3v power supply source and cutting the gray wire and running 40k-150k ohms in line. That used to work great up until that last 3 ps3's I have fixed. It will start running the fan @ 50%(ish) and after 5-10 min. the fan will be barely running at all. So my method is out the window. Time to use your method.

I've observed this. It's like Sony WANTS their machines to have a short lifespan.

Anyway, I've made a few interesting discoveries but I'm so bloody disgusted with the PS3 dev scene toward DRM dongles that I'm through with sharing. I really wish I had never posted any of this information.