Dual LED & Dual Voltage Baybus!

Well folks, here I go again! After a successfull attempt at making myself a home-made LED Baybus, as pioneered by Cliff A of Fanbus, I decided to try my hands at the Dual LED & Dual Voltage setup. I gave the schematic diagram at Fanbus a long, hard look and said to myself, "I can do that too!" So off I went to have the necessary items ready once again!

You might be asking why do I need a dual voltage baybus for my fans. The main reason behind it is the need to have a little peace and quiet by running your monster fans at a lower voltage. Lower voltage means lower spin rate, and lower spin rate simply means less noise. And I'm sure many of us would love that when just spending some surfing time on your puter.

As for this guide, I am assuming that you guys are already familiar with basic electronics and wiring diagrams. And also the use of simple tools like the soldering iron and the hand drill. So I'll be skipping a few steps. Let's get to it then! In this guide, I'll be showing you how to make a 5V / Off / 12V Baybus with Dual LEDs (Blue & Red) to indicate the different voltage state. The basic items are;

As usual, you need to mark out the position of the switches and LEDs on your 5.25" faceplate. Drill the correct sized hole and mount them onto the faceplate. Once mounted, leave them on and place the faceplate onto a jig or clamp to start the soldering. You should be able to get something like this.


Items required
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Faceplate done
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Dual position switch
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Rear view with LED Holders
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As you will be running on dual voltage, you will need two different resistor values. Here's the formula again.

Voltage = 1.5V, Amp = 0.015 A. Therefore, to calculate resistance needed for a 12V line-in;

Ohm = (Mains Voltage - LED Voltage) / LED Amperes, so;
Ohm = (12 Volts - 1.5 Volts) / 0.015 A
= 700 Ohms or 750 Ohms

Voltage = 1.5V, Amp = 0.015 A. Therefore, to calculate resistance needed for a 5V line-in;

Ohm = (Mains Voltage - LED Voltage) / LED Amperes, so;
Ohm = (5 Volts - 1.5 Volts) / 0.015 A
= 233.33 Ohms or 240 Ohms

Important!
Now we come to the tricky part. I am using a DPDT switch. This switch has an "ON/OFF/ON" state. The "OFF" state is useful if you want to stop the fan. At the back of the switch, you will see 6 terminals altogether. An electrician friend of mine said that the best way to test which set of terminals will respond to which position of the switch is to test it with a multimeter. He also mentioned that the middle terminals are the common terminals, meaning your voltage line-in should be soldered there. I decided to test it the old fashioned way. Hook it up with the wires and some electrical tapes and use my external PSU to test it. Not really very productive, but what can a cheapskate DIY'er like me do? :O)


State indicators
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So after about an hour or so of testing, this is what I get. I wasn't very convinced at my findings initially, coz it's very different from what Cliff has on his website. I decided to bring the switch over to my friend's shop and have it tested with his multimeter. He said that I was right, and that this is the arrangement of the terminals on the switch. Well, I guess it would differ from other brands or make of the DPDT switches. No matter what, I strongly advise you to test the switches first. It would save you a lot of time and effort, not to mention money too!


Groupings of terminals
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Wiring setup
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Once you got that out of the way, it's time to proceed to the wirings. I also suggest you put some kind of markings on the switch to prevent any confusion during the soldering part.


Faceplate on clamp
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Line-in wires soldered.
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750 Ohms resistor
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Continue to do the same
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And don't forget those heat shrink tubings. It really helps to prevent short circuiting of the wires and also makes the baybus setup looks much neater. Take your time and make sure you got the wires at the right terminals before soldering it on. Check...and counter-check!!

If you did it correctly, you should obtain something like the pictures below. Try to arrange the wires properly and neatly. It would help you trace any problems with the circuit much faster. If you can, connect the LED's the way Cliff has done. It will be much easier to change the LED in case it's damaged. I am using the Blue LED to indicate 5V and the Red to indicate 12V.


Control unit completed
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Rear view
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Very messy and confusing!
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Close up on LED Connectors
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And since this is a 5V / Off / 12V setup, the 5V Line-Out can be combined with the 12V Line-Out. No, this is not a "7V trick", but rather the voltage supply is controlled by the DPDT switch in the faceplate. The 5V is the red wire, and the 12V is the yellow wire. And do not forget to include the 5V line into your Male Molex connector.


5V out & 12V out together
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Male Molex connector to PSU
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I also soldered the Black ground, or "negative", wires from the LEDs and from the Molex connector together and use a screw on type wire connector.


Ground wires soldered together
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The Fanbus is the easiest part of the unit. Just drill some holes on the removable cover and screw on the spring wire terminals onto it. Then solder the appropriate wires onto the terminals, Ground, or "negative", on the black terminals and 4 individual "positive" wires to the red ones. These "positive" wires are used to receive the 5V or 12V signal from the control unit and channel them to the fans.


Fanbus ready for soldering
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Common ground soldered
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5V/12V lines soldered
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Completed Fanbus
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Completed Unit
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Once the fanbus is completed, connect it to the Baybus control unit and you should get something like this.

Since this is a Dual Voltage unit, I could not test it with my external 12VDC PSU. I had to opened up my HX08 Tower to access the female Molex connector from the PSU to get the 5V signal. Here you can also see my other obssession I have with Sunon fans!! From the 60mm, up to the 120mm! They were used for the test.


Test bed!
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Sunon babies! 60mm up to 120mm!
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I powered up the system & proceed to test the unit. First stop was the 5V line. The Blue LEDs lighted up, indicating that I had the circuit correct. The 60mm, 80mm and 92mm all started up without a hitch and continue to spin. The 120mm had a little trouble starting up though! Please take note that different fans will have different start up voltage and will react differently towards the 5V signal. Underpowering a fan will not damage the fan, neither will it extent it's lifespan. So you do this at your risks.


Blue LED for 5V....
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All OK...except the 120mm! :O(
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Now it's time to test the 12V signal. With a flick of the switch, the Blue LEDs goes off and the Red LEDs lighted up, again indicating the correct circuit wiring. This time, all the fans spins at their rated capacity. One thing to take note is that "none of the fans stalled when switched back to 5V!". Which is great!


Red LED for 12V....
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COOL! But noisy!
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Dual LED goodness!
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Finally, you now can turn down the "volume" of your PC fans when you're just surfing the web or doing some work. Now, you might find that your fans would not spin comfortably in 5V, so as Cliff A would say, "Out of necessity, comes invention! In the form of what is commonly called the "7 volt trick". That's exactly what I have in mind next for you guys! So stay tuned! Here's the schematic diagram of the circuit!


Schematic diagram
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As usual, mail me with your Qs or feedback! Happy soldering!