Project: Madness (a Fan/Electronics modification)

As mentioned fan in darkness run with black gloss fan blades.

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Looks fine but is just not as brightly reflecting as I would have hoped. Maybe I will bung a coat of lacquer on top of the black and see how that comes out.

I'm wondering how it would come out with a white blade now but I don't have any white paint to test at the moment, it all went on some curtain rings a few months ago.
 
Wowzers that is extremely impressive. I think if you want to get as reflective as possible you'll need transparent/translucent blades.

Will you be miniaturizing the electronics? Or is that not feasible? Circuits are about as comprehensible as ancient greek to me :p.
 
joxang said:
Wowzers that is extremely impressive. I think if you want to get as reflective as possible you'll need transparent/translucent blades.
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Hmm maybe you are onto something there. I have a semi-transparent LED fan that came with the Alpenfoehn Brocken cooler. Might be worth a try bunging a few LEDs in that and seeing what effect it gives.

I did have my eye on an Enermax TB silence a while back as they have semi-transparent blades too and rather fancied it for the older static LED mod. Not sure if I want to spend £10+ on a fan though just for this.

We'll see. Will try out the fan I have first. It's just a matter of drilling 18 equispaced holes and hot glueing a few LEDs in.

joxang said:
Will you be miniaturizing the electronics? Or is that not feasible? Circuits are about as comprehensible as ancient greek to me :p.
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To be quite honest with you I'm not sure if it is possible to reduce the electronic footprint down all that much and keep the circuit working the same way. If it weren't for the 18 dimming circuits the board could be relatively small, especially if I had more experience on PCB layouts.

The following video illustrates what the LED sequence would be like without those additional circuits. It's clever and everything but it can't compete in my opinion.


As mentioned above it is simpler to make this circuit using a PIC microcontroller, which is a chip that you can write code to so that it does certain things. I may very well grab one of the USB PIC programming thingies and see if I can make something similar. The footprint of that will be much much smaller.

And don't worry circuits are still mostly Greek to me too. I've only really taken an interest recently but had already dabbled with LEDs, but that was just LEDs and resistors, nothing more complex.

I did Engineering in college and Electronics was part of that course but I never got to do anything interesting, it was all maths and stuff. Boring.
 
Hopefully I can answer.

The 4017 chip apparently only puts out about 6mA of current so while it does illuminate I wouldn't call it super bright.

The video (shown above and here) is fed directly off the 4017 IC.


Here's an out take of the original schematic I posted.

dim-circuit.jpg


This small circuit was cobbled together from a circuit I saw on pcbheaven which basically was the same with the addition of a potentiometer going to ground between the second transistor and the 2k2 resistor.

My limited knowledge tells me that when the base of the first Transistor goes high current flows from the collector to the emitter, fills the capacitor and activates the second transistor which in turn powers the LED. When current stops flowing from the 4017 decade counter the first transistor switches off, and the capacitor releases it's charge through the second transistor comparitevly slowly because of the 2k2 resistor. If I use a larger capacitance such as 220uF the LED would say lit for several seconds. if I increase the 2k2 resistor I would also get a longer dim effect. I messed around with many different values before deciding on 2k2 and 10uF.

Ideally it would be great if the dim time would increase as I slow down the seqeuncer but that's tricky to do with passives.
 
Yeah it would be difficult to do to vary the fade, you could do it by connecting the negative of your capacitor to a potential divider which is affected by you turning the POT. Probably not worth the faffing to get the values correct.

You seem to be missing some current limiting resistors so it may shorten the life of the circuit
 
Whereabouts am I missing them mate?

Originally I planned to have one on the return but for some reason the dimming effect was lost. I don't have an ammeter so haven't been able to check current to the LEDs but reckon it is actually less than 20mA because they are not fully bright. There is very little difference on brightness between voltages too. If installing it in a PC I might regulate tge voltage down from 12.

Once built I did run the circuit at 12v for 18 hours or so to check for led failures.

Can you think of any improvements?)
 
I would put a resistor on the collector of Q1 to 12V as the only thing limiting the current is the LED itself and the small resistance across the transistor. The value will depend on the LED's you have.

I just checked the current rating of the transistors, 200mA Continuous(absolute max) which you are slightly exceeding with R6 at 56ohms, try and increase this a bit (82ohms) but the more you increase it the longer the cap takes to charge.

I'm not sure of the output from the 4017 if it needs pull downs or not.

I hope this helps
 
Just run Multisim and it says the current flowing before the LED is a whopping 215mA. Surely it'd blow in no time if that were the case.

Maybe I will have to get myself an ammeter and check real world. I will have to slow the sequence right down though as it's too fast to grab a reading.

It's going to be a real pain to get a 400-500 ohm resistor on Q1 as it shares a track with the collector of Q2. Hmm it might be possible to shift Q2 down a track or two or break the tracks and use link wires.

Bit concerned though about brightness as well. They are already below maximum brightness even at 12v so bunging a limiting resistor in will surely reduce that further.

Thanks.
 
Very nice job!

Couple of points . . . .

1. You soldering needs practice :p. Got a decent temp controlled iron?
2. Those wire bridges look rough, I use the leads clipped off the components when the length is ok, otherwise, buy some uninsulated wire on a reel. I know it doesn't make much difference, but its the looks of it, innit.
 
This is like the one I have. It's pretty basic but does have enough power.

1.jpg


Any inconsistencies in the soldering is probably due to my slight hand tremor and inexperience, this coupled with the fact that I made a million mistakes.

I know the joins were a bit of a hack but I kept losing tracks on the veroboard because I left the tracks a bit short in places. Ideally I would care more about the appearance but meh. :p


Just picked up an über cheap multimeter with current measuring capaibility of eBay. It's not an auto sensing one like mine but it'll do for stuff like this I'd imagine.
 
Tealc said:
I initially didn't think about using PICs due to cost of buying the programmer but after spending a fair bit on all the components anyway I probably wouldn't have been much out of pocket. It's true though that I now have a good selection of components for any future projects as even though this project only needed 1 or 2 of things I've bought 10-100 of them.

I've been looking at pic programmers though and not sure what to get. Is there anything I need to know before making a purchase?
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if you look at the link i posted, there are freebies around. Like i say, i really enjoyed using AXEPAD, but thats only does BASIC. If you're more of a flowchart person, then theres also a freebie flowchart programmer in the same link.

If you want to buy one, then at school we used PIC logicator. I believe the single user version is something like £15. And that primarily owrks with flowcharts, but has the function to convert it into BASIC and then carry on programming in BASIC (handy feature when you're trying to learn how BASIC works)
 
thingemajib said:
if you look at the link i posted, there are freebies around. Like i say, i really enjoyed using AXEPAD, but thats only does BASIC. If you're more of a flowchart person, then theres also a freebie flowchart programmer in the same link.

If you want to buy one, then at school we used PIC logicator. I believe the single user version is something like £15. And that primarily owrks with flowcharts, but has the function to convert it into BASIC and then carry on programming in BASIC (handy feature when you're trying to learn how BASIC works)
Click to expand...

I was more talking about the actual hardware that you plug into your PC that allows you to program the chips, rather than the software, but thanks mate. :)

I've used BASIC since the 80s so am quite familiar with it but can adapt. I would imagine I would go for free stuff rather than paid for stuff because I'm tight and this is just for fun.

I saw a USB K150 USB pic programmer on eBay for £15 notes, do you think that would be sufficient for me to program a decent PIC?
 
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After some investigation into my dimming circuit it seems that the voltage to a UV Purple/Blue LED is only 3.6v at a 7.5v power source lowering to 3.0v for a 4.5v source. The current may be well high and I will check that when the multimeter arrives but I've noticed if I replace the R6 with a higher resistance the voltage for the LED drops further.

I think I can add in a resistor to Q2 collector without a massive amount of trouble to get 20mA for a single LED but if I then decide to add several fans to the controller board they'll get only half the current.

The original plan of having the resistor attached to the return was better, shame it didn't work.

Need to do some more experimenting it seems. I knew I should have built it properly on solderless breadboard but I only have the one and it was busy enough with just the 10 LEDs fitted. My inexperience showing through perhaps. Oh well it's all learning fun and keeps this prooject going a bit longer.

Tried lacquering the Orange fan up and it didn't work at all well. The existing paint seems to have reacted with the solvents in the lacquer and gone all blotchy and very matt. I will need to strip that and get some proper orange extra gloss paint.
 
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yeah the 200mA or whatever is no surprise. It wont actually be at that but it will be high. The LED will be at its maximum brightness at 20mA or whatever its specified maximum current is any more current is out of spec even though it may be brighter.

As the LED is flashing you would get away with this over voltage and too high current for quite a while but it will shorten its life.

you could design it so the brightness is unaffected by the amount of LED's connected. As long as you make it so the LED's connect in parallel with their own resistor it would be fine.

I will draw you up something quick :)

Hope im helping

Shane
 
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you can add as many as you wish in that fashion, the limiting factor would be the current through Q1 which absolute max is 200mA. Say if you wanted more than 6 -7 LED's just double up on Q1
 
Will give that a shot. I can easily add a resistor (got loads of them) to each LED anode. If it is driving massive current then I understand that limiting it to 20mA would be best.

Not sure what is happening to my led voltage though. Surely it should be near source voltage, yet it's pulled right down.

Seeing as I'm only dropping 2 or so volts I could use my 56 ohm ones.
 
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