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DIY Fanbus schematics

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Black_Ops

Member
Joined
Jan 5, 2003
Location
TN
Tri-color LED fan bus 5/12v version!!

Hello, i would like to present my nice and cool fanbus schematics.
what makes my fanbus different from the rest you ask?

well my fanbus (4 channel) is a dual voltage fanbus, but thats not all, insted of bi-color leds to indicate speed, i have used tri-color leds.

red = off(0v)
green = low (5v)
blue = high (12v)

well here are the schematics http://www.maxvla.com/host/Fanbus.pdf
 
Last edited:
You should only post in one section, not make the same post in several threads.

If you feel that your thread belongs in the wrong section, you should instead contact a mod and request to have it moved..
 
Hi, Joseph.

First off, sirtoby is absolutely right. At any rate, I'm going to post here because GC strikes me as the proper forum for this topic. Just a few comments ...

Nicely drawn, but a bit jumbled. Since each channel is identical, you might want to make a schematic with just a single channel. In my opinion, this helps simplify the drawing, leaving it easier to read. (In my early morning grogginess after spending all last night proofreading a thesis draft, I'm having a harder time following those traces than I'd like to admit. ;) ) This also makes revision simpler, as you only need to modify a single channel.

Your tri-color LED connections are unclear. After staring a bit, I've decided that it's what you must mean by the #1 Hi, #1 low connections. Is that correct? You really might consider drawing the correct symbols for the LEDs and placing them in your schematic. Here's an example with bi-color LEDs:

basic_design.gif


(One color indicates full voltage to the fan, the other variable voltage. I wouldn't fret much about the rest of the design at the moment.)

It looks to me like you're trying to use some sort of voltage divisor-like circuit to drop the voltage from 5V for your LEDs. However, it appears to me that as you've placed the resistors parallel to the LEDs and there are no resistors preceding or following those LEDs, they will still receive a full 5V. You should modify your design to have the resistors on the ground side of the LEDs. Furthermore, you can eliminate some resistors from your design in that way.

Lastly, I don't see anything to indicate an on/off switch for each channel. I see 5V / 12V, but no ON/OFF. As such, I see nothing there to switch the tri-color LED to its third state. A logic circuit could be used to take care of that, I suppose.

Good luck, and have fun! -- Paul
 
it was suggest by a friend that i also post it in the general section, sorry if i violated a rule or something.

Ah. you must of been realy sleepy.

the design was drawn for 4 channels to illistrate the 4 OR gates of the 74LS32. the tricolor leds are wierd common cathode and each element has different voltage and amperage requirements so the resistors extra resistors are needed. the 3rd state led (red) goes on when both hi and low inputs are low meaning switch is off the logic gate output goes low and switchs the pnp transistor which activates the led. all 3 elements are in a common package (T-1 3/4)(5mm). the circuit works just fine. the only resistors not realy needed are the weak pull-down ones on the first page. and that is the correct symbol for led.
 
LOL, I only saw the first page. Well, I guess that would explain my strange comments, as I was only working off of half of your circuit. :) I think the second and third pages hadn't loaded on my 56K modem at the time I was looking it over. Ah ... That's much better ... :D

I'll enjoy studying the second half of your design sometime soon. But for now, it's time for a walk and dinner. Thanks for the clarification. -- Paul

BTW, not a rule so much as good form on the multiple-posting. ;)
 
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