Forthcoming mods - fanbus, new lighting, and blowhole!

[Oliy]

Finally decided that I couldn't wait any longer (I wasn't really waiting for anything anyway, just being lethargic) and ordered some stuff from Maplin.

A few days ago I got to rip apart a "broken" PC that my friend let me have (think the motherboard was dead, everything else seemed to be fine) and I looked at the power supply - a 230W Sparkle, I didn't need it, but it looked like it had a 92mm fan on it which I fancied (you can never have enough fans, and the exhaust fan on my case is 80mm, and I fancied a bigger one). So I cut out the grille in the back of my case, put on a wire grille and installed the new fan, which is a beast - the airflow is probably about triple what I had before, although the lack of case grille might be helping a fair bit.

While I was doing that, I managed to snap my green cold cathode - they're so fragile! So I ordered a new blue one, and while I was on the site I saw a red, sound activated one for only £3, and couldn't resist. However afterwards I discovered it was a sound activated neon light rather than a cold cathode - do neon lights take more power? Do they output more heat? Any info would be gratefully received!

I also ordered a 16 piece hole saw set - I only want one saw to drill one hole, for for only £5 it wasn't too bad, and I plan to cut a few more holes in the side panel for decoration too seeing as I'll have the whole set!

The rest of the stuff was for a series of rheostats, or fanbus, for 3 of my case fans (I'm not sure on the correct term, but basically a controller for fan speeds!)

I'm going to be building it myself. I'm using the circuit attached, which basically involves a 555 timer creating a voltage ramp. For each fan there is an op amp comparator in infinite gain, which compares the voltage of the 555 with the voltage given from a potential divider with a linear potential resistor. The output of this will drive a high power mosfet.

The output will be a pulse width modulation signal, PWM, which alters the speed of the fan depending on the duty cycle.

I plan to have controls for 3 fans in a 3.5" bay cover.

[Todd a]

Neons suck. They are much bulkier, draw about twice the power, and dont last very long.

[Oliy]

Bah. No wonder it was cheap. By twice the power, are we talking 6W+ ? I should be able to handle that, I think!

[Todd a]

Here in the states there is a place I order my mod stuff through and they charge $4.99 for a dual inverter and a 12" cold cathode. Asecond cold cathode (4" or 12") is $2.99. I don't pay taxes on it and they have very cheap shipping (about $5 max for an entire order). They also have UV cold cathodes for $1 more LED fans for $3-6 (including UV LED dual color fans). Window kits for $5. They have wire fan grills for $1 and laser cut ones for $2-3. I can completely trick out an old case for $30-40 like this old case I got for free:

[Oliy]

Well my stuff arrived today - the blue cold cathode was broken, surprise, so i'll have to go into town later to get it replaced

The red neon isn't too bad actually. Yes, the tube is quite small and bulky, but it gives out a bright light, and according to the packet consumes less than 3W, which is in a par with the 300mm cold cathode. The sound activation is really cool, i've adjusted it so that a clap will trigger it, (a clapper.. so I can find my computer in the dark if I lose it..) or the bass from my hifi at a reasonable volume!

The electronic components all arrived too. Not sure when I will have time to assemble it all as we are midway through decorating the kitchen - new floor to lay, walls to paint and everything!

[agw_01]

Nice one Oliy.

I'm sure a lot of people have recieved damaged cold cathodes. They are so fragile that even the slightest knock can crack the tubes.

Are you building your rheostat/fan bus? If so, that's cool. I don't have the time to sit down and experiment with electronics these days, but in my early teens, I used to love building circuits and seeing what I could *invent*. All I got out of it was a couple of burnt fingers (who would have thought 1.5v AA batteries heat up quickly when YOU try to hold on paper clips to use as wires), hehe.

I'm thinking of getting a few red cold cathodes to use in my next project... black case/red neons

Hope to see some pictures soon, and good idea about the clapper

[Oliy]

Yeah I'm building my own fan control thing, from a 555, some op amps, mosfets, potentiometers and strip board! The potentiometers and the knobs i got for them feel very smooth and professional, so if I don't completely arse up the drilling of the holes in the bay cover, it should LOOK and feel fairly professional to the average person.. of course my soldering (especially with a soldering iron with a tip the size of a small automobile) leaves a bit to be desired so the inside view wont be nearly as pretty!

I'll hopefully be able to have a go at that later this evening.

I also plan, as well as the blow hole, to cut some extra holes (my hole saw kit goes from 3/4" up to 5") some over variable sized holes in my side cover as "windows". Anyone got any suggestions as to size and placement etc? Perhaps randomly arranged... or some underlying order? (See attached picture!) The holes are to make the side panel look good, but also so that you can see inside.

Thanks

[grover]

The placement of your big hole in that sketch will be mostly obscured by your drives and/or PSU, won't it? For my case, I was thinking of (but never got around to) cutting a single gigantic hole, and cutting blowholes/fan holes right in the plastic.

[Oliy]

Okay, I didn't have a good time cutting out that hole. In fact, it was a nightmare, so the cutting mods are ended for the moment until I get my hands on the proper equipment.

I did manage to get it done though, but the result was absolutely horrible. The only good thing about it was that it was more or less the right size.

I did the only thing I could do - covered up my shoddy work My eyes alighted on a can with a plastic lid which looked just about the right size. A few minutes of scissors and a razor left me with the perfect bezel for my blowhole. It actually looks rather smart too with the black fan grille!

Here are the pics. I havn't connected the fan yet because I want to attach another one, this one is just for show. I want to get the fanbus done (started) tonight so I can connect up a fan proper.

[fire]

Nice job of the fix of the hole look good.

[Oliy]

The PWM fan controller is up and working!!

Unfortunately one of the potentiometers was also damaged during transit so I need to get that replaced before I can finish it. However, two of the controllers are fully functional - the fans just stall at minimum level, and, as far as I can tell, run full revs at max, and in between varies very nicely with the controller.

At first I couldn't get it to work - changing the potentiometer did nothing to the speed of the fan... I was very confused, and annoyed, seeing as I had no multimeter to test any voltages!! After a visual inspection I found nothing wrong.. but of course I had overlooked something, one tiny wire not soldered in! I fixed that in a few seconds and it was all working, and I was very pleased!

The mosfets don't even seem to get warm, although I will let it run for a bit at max power to make sure. The 555 and the quad op-amp source virtually no current so they are not a problem.

Here are some pictures - like I said, I will finish it off and attach to the bezel once I have the third potentiometer.




All my pictures so far can be found at:
http://www.ohdb.co.uk/oliy/members.a...ges%5CComputer

[Todd a]

You need to mount that thing in a drive cover. Looks good though. Most fans don't like opperating below about 5v (even some have trouble that low).

Sound activation is neat, but not for me.

I think to finish off the front of my new case mod I will paint a logo of some sort or add a sticker. I will also add a case badge and an fan controller that is lit with blue lights. I'm likely going to use a seperate USB, FireWire, headphone jack box in the floppy bay.

[Oliy]

I don't know the exact shape of the sawtooth generated, so I can't work out the duty cycle. I might model it later to find out, but I'm not particularly bothered

Going into town today to hopefully get my potentiometer and cold cathode replaced. Chances of them having both in stock are probably quite slim

[Oliy]

My modifications are complete! I visited Maplin today and they exchanged my broken cold cathode and potentiometer for working ones.

I finished the PWM fan controller, and then drilled out the 3.5" bezel. I had to saw off about half of each rod on the potentiometers - they're solid steel, so it took a fair amount of time!

I mounted my blue cold cathode across the middle of my case - a bit unconventional, but it gives a good light out of the exhaust fan, blowhole, and side vents, as well as a little out of the front vents, so good all round lighting! I mounted the red neon over the side vent.

I'm currently sitting here with the lights off, enjoying the show

Here's what it looks like finished:

PWM Fan Controller:



Blowhole:


New case lighting:

Thanks for everyone's feedback, I'm very pleased with the results If anyone else is planning to build a PWM fan controller themselves I'd thorouhgly reccommend this one - it's cheap, fairly simple, you don't need any special components, and it can easily accommodate 4 fans. If you need any help, just contact me and I'll be happy to give advice!

Cheers

[Todd a]

Much better.