# I have a wiring question for someone who knows the answer



## Jason9922 (Jan 14, 2012)

Over the past few years I have accumulated a few laptop coolers. All of which worked ok but as I would get a different laptop I would need a different cooler. Well now I have another newer laptop and would like to take the fans out of the laptop coolers I have and use them on one that I am going to make. I work at a machine shop and have access to lots of metal working tools. I plan to take a sheet of copper (maybe aluminum) and bend it into the same shape as the laptop cooler I have that's made of thin flimsy aluminum. I might even use a thick piece of copper on top and make the rest out of aluminum because copper coducts heat away so well. Anyways, I have five 5 volt USB powered fans. One set of 3 is connected to one laptop cooler and has a on / off switch. The other is a pair that's connected to a mini laptop cooler just by the USB. When I make this piece for my laptop to actually sit on I am going to cut out holes for the fans to rest perfectly in underneith so the 3 fans are blowing up at the hottest place underneith the laptop and the other 2 fans are exausting that hot air down and out. If anyone thinks I should place the fans in a different way, now is the time I would love your input. That's the way I have them jerry rigged right now and they drop the temp of the laptop by 40 degrees almost.

*My biggest question and the reason I wrote this is can I wire all five 5 volt usb fans together in series, then run those soldered wires through the on / off switch I'll have??* 

I watched a few videos on youtube where a few people said this was ok as long as they weren't wired in parrallel. So wiring them in series pretty much just means disconnecting all five fans at the ends of the wires and clipping them. Then stripping the ends of all five black and red wires on each fans. Tying all the black ones together, tying all the red ones together, then soldering them together. Then taking the long USB tipped wire with the on / off switch, strip the ends of the black and red wires at the ends and then soldering those to the wires from the 5 fans?? That's pretty much what I was told to do. I am just wondering if it will work. Seems like running all five 5 volt fans off one USB port could be a lot but I am not electrician. If anyone can help with this I would appreciate because the laptop cooler is going to look very pro and not some ghetto cardboard mess. I'm going to make it look nice and mount the fans so it all looks like it came from a store. There won't be electrical tape all over everything.

Thanks!

Jason


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## gcavan (Aug 13, 2009)

First of all, you are confusing the definition of series and parallel circuits. 

A series circuit would have the fans connected, red to black, down the line, with the red from the first and black from the last going back to the control circuit.

A parallel circuit (what you are describing and the correct way to connect your fans) has the reds and blacks respectively tied together. 

Paralleling your five fans would be the correct way to connect them, however I suspect the current they draw may overload your USB (maximum 500mA). Check the total current draw with a multimeter.


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## Jason9922 (Jan 14, 2012)

I should have been clearer. I was talking about "series wiring" and "parallel wiring" like the way you wire up stereo speakers to lower the OHMS sometimes. An example of wiring speakers in series is just connecting all the reds to the red and all the blacks to the black. Parallel is running a red to the positive on the speaker, then run another wire from the positive on that speaker to the negative on that same speaker, then running another wire from that negative to the positive on the next speaker, then another wire from that positive to the negative on the 2nd speaker, then running a wire from that negative back to the black wire that runs with the original red wire you started with. Sorry if that’s real confusing. I have no idea about the circuits. 

*So the correct way would be to tie all the red ends together and all the black ends together from the fans to the red and black ends from the stripped single wire that eventually goes to the plug?*

*I planned to solder the six red and six black connections together. Is there a different way I should do this?*

I don't know much about this kind of wiring. All I know how to wire is stereo equipment. House / car stereo._* Is there something like a distribution block used with car amps that I can use with this set up?*_

I have 2 usb cables with ends so I can wire 2 fans to one wire and 3 to the other if you think that would be a better idea. I just want it to look nice so I figured tying into one USB plug would look nice. Thanks for the help!


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## gcavan (Aug 13, 2009)

Wrong! I repeat; you are confused about the definition of series and parallel wiring.

"An example of wiring speakers in series is just connecting all the reds to the red and all the blacks to the black." *This is a parallel circuit.*

"Parallel is running a red to the positive on the speaker, then run another wire from the positive on that speaker to the negative on that same speaker, then running another wire from that negative to the positive on the next speaker, then another wire from that positive to the negative on the 2nd speaker, then running a wire from that negative back to the black wire that runs with the original red wire you started with." *This blows your amp as it creates a dead short across the output.* 

A series circuit would be positive from the amp to positive lead on first speaker, negative of first speaker to positive of second speaker, negative of second speaker to positive of third, and so on. Negative of last speaker goes back to the amp.


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## Tyree (May 10, 2009)

Series on the left & Parallel on the right.


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## Jason9922 (Jan 14, 2012)

Yes I wrote that in a confusing way. Sorry about writing something I thought at the time was correct in my mind. Again I apoligize for my own confusion.

GCAVAN:
"Paralleling your five fans would be the correct way to connect them, however I suspect the current they draw may overload your USB (maximum 500mA). Check the total current draw with a multimeter. "

@GCAVAN:
Instead of taking the chance of messing up one of my USB ports,
Is there a way I can wire these five fans to a cell phone charger AC adaper? The reason I ask is, when I looked this up and googled it, some people said that on most newer cell phone charger AC adapers, when you strip back the black jacket there is 3 wires. Red, Black, and yellow. Here is where a lot of people said the cell phone charger AC adapter "yellow" wire is a 5 volt wire. When I googled this the person on another forum was asking how to use the same charger adapter to hook up 12 volt fans and this is where I noticed people told him he could use it, using the red and black wires, and to ignore the yellow 5 volt. 

*Could I connect the 5 red power leads to the yellow wire, then connect the 5 black ground leads to the black wire, solder them off, and ignore the red wire from the AC adapter?*

After seeing what you said about wrecking my USB port or even chancing it, well I use my laptop hooked up with the AC adapter 100% of the time so instead of wrecking a USB port, I was thinking of just using the cell phone charger if I could to power the fans and not risk the USB port problem.

I HAVE ATTACHED SOME IMAGES I MADE ON PAINTBRUSH SO SOMEONE CAN LOOK AND TELL ME IF ANY OF THEM LOOK USE ABLE OR WHAT IS WRONG WITH THEM. THANKS IN ADVANCE!!!


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## gcavan (Aug 13, 2009)

> Check the total current draw with a multimeter.


Have you done so as yet? If the fans have the maximum current rating (in amperes [A] or milliamps [mA] printed on their respective labels, you may use that. In any case, the total will help you decide on how to procede. And I cannot advise you without knowing.

Re cell phone chargers: I've never taken the time to look at one, though I suspect the red wire is power, and the yellow is a 'sense' or feedback lead used by the circuitry within the charger to determine phone battery state of charge. The name plate on the chargers will tell you their respective operating voltages (could be anything from 3 to 9 volts) and maximum charge current (usually around 300mA).
You could also use a multimeter to determine the potential at each wire.


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## Jason9922 (Jan 14, 2012)

I don't have a multimeter I don't think. I have a voltage tester thing. Its a yellow box with a dial and you can turn the dial from 12 volt or AC. I am unsure if this is a multimeter and don't know how to read it. Let me mess around with it a little. I am sorry I am so iliterate at electrical terminology, its something I've never really played around with because I've always been so worried about wrecking things, causing fires, and I was electrocuted badly when I was younger so I often sear clear of these types of things. LOL. The fans have no numbers or anything anywhere showing how much power or current they are using. I just assumed wrongly that since I read laptop coolers use 5 volt USB fans that that's what they were. 

*With the meter how would I check the current rating or milliamps when all the wires are connected. (I haven't torn apart the 2 laptop coolers yet, they are still altogether. I wanted your advice before tearing things apart and making a mistake.)*

*Should I stip the BLACK jacket from around the USB plug main wire, then strip the jacket back on the red wire, test it while its plugged in? Or should I test the main red wire while plugged in after where its connect to the switch passed the fan while its plugged in to see how much power its using? Sorry for making this so complicated but I just want to be sure before I start cutting wires. LOL*


I'm pretty sure this yellow small box like tool with the dial is a multimeter because there are a ton of settings and obviously it reads more then just voltage. It has a red and black wire coming out with a touch tool on the ends thats copper. I'll check it out.


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## Jason9922 (Jan 14, 2012)

@GCAVAN

Ok, The tool I have is a multimeter. I've posted the datasheet so you can see which one it is. I am sorry but I have no clue how to set it or how to use it. Again I apologize for the no skills. If you could explain how to set it and what to look for, the process I need to do to give you the correct info on how to proceed I would appreciate. Thank You sir.
:ermm:


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## gcavan (Aug 13, 2009)

How To Use A Multimeter - SparkFun Electronics

PS: Place the black probe at the *COM* socket. To measure voltage or resistance place the red probe at the *VΩmA* socket. To measure current place the red probe at the *10Amax* socket


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## Jason9922 (Jan 14, 2012)

I know how to plug the probes into the multimeter and where its supposed to be set at. I don't know where to get readings from on the actual fans. Its not like they have circuit boards. So I assume I am going to have to strip the red wire without cutting it to test the current while its plugged in. Exactly what I didn't want to do. Mess up and cut the wire, then have to fix it correctly. I was hoping there was a place on the switch where I could get the reading. Between the forums I asked for help someone will have clear directions.


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## gcavan (Aug 13, 2009)

You currently have this (or similar) X5, and a +5VDC source, correct?


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## Jason9922 (Jan 14, 2012)

Yes sir, I have 5 of those same exact fans. 3 are connected in the pile of junk laptop cooler I bought and was refunded for, and 2 are inside one of those mini laptop coolers with the 4 fold out plastic legs so it kind of looks like an X. I'm going to show pics down below so you know exact what I'm looking at. All the fans are wired in. I have no idea where to take reading from. I know the 3 fan one thats aluminum looks like it would be nice, but its made of the thinnest metal it bends like cardboard when you try to pick up the laptop with the cooler attached. Anyways here are the pics of what I am working with. I want to take these 5 fans and either wire them alotgether to use on one USB port if possible, But I would prefer to take all 5 fans and wire them to an AC adapter plug somehow so my USB port doesn't get smoked. Thanks
Jason


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## Jason9922 (Jan 14, 2012)

hey can you give me a hand with something? I got the info you wanted


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## Jason9922 (Jan 14, 2012)

So this is the deal with my laptop cooler I'm making now. I want to use the 5 fans that I'm going to take out of the laptop coolers in the pictures. I have come to the conclusion after a lot of reading that using my USB ports to power these will just burn out the ports quicker. Either way when I checked the power draw from the 3 fan laptop cooler it was drawing 2.4 volts and the other 2 fan mini cooler was drawing 2.6 volts equaling 5 volts total. Many have told me that USB ports max out at 5 volts. Well I didn't know that when you connect mulitple USB devices the USB BUS divides the power from 5 volts to 1 device to 2.5 to 2 devices. Anyways, I would like to connect the 5 fans to a 120 volt wall plug using a cell phone charger I have. 

This info on the plug -INPUT: 100-240 VAC 50 - 60 HZ 01A OUTPUT: 5 Volt DC 350 ma 

Now I'm assuming that means it outputs 5 volts like a USB port and can handle 350 Milliamps? Like I said that's an assumption so I'm asking. I don't know how to find out how many Milliamps the fans put out. I was thinking wiring the fans to this plug would make them run faster and would put no stress on my laptop then if they were plugged into the wall. I have another charger thats similar and the end was cut off so I stripped the 2 wires, plugged it into the wall and checked it with the multimeter and got 5.37 when the multimeter was set at 20/V- and 11.1 when the multimeter was set at 200/v (with a squiggly line instead of a straight line). Does that mean 5.37 volts and 11.1 amps?


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## gcavan (Aug 13, 2009)

> Either way when I checked the power draw from the 3 fan laptop cooler it was drawing 2.4 volts and the other 2 fan mini cooler was drawing 2.6 volts


This tells me you probably have them wired in series. 
They will not "draw" any voltage; they will accept whatever voltage is supplied by the source. When two loads are connected in series the voltage will be 'split' between the loads in proportion to the internal resistance of the respective loads.



> I'm assuming that means it outputs 5 volts like a USB port and can handle 350 Milliamps?


Correct.



> 200/v with a squiggly line instead of a straight line.


 This is for measuring AC voltage. Do not use here though it should, it fact, read zero in this case.


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## Jason9922 (Jan 14, 2012)

Well I never took the laptop coolers apart yet, still waiting on how to wire everything correct so as of right now, the 3 fan laptop cooler and the 2 fan laptop cooler both have their own USB plugs. I checked the power draw on the 3 fan laptop cooler where the wires connected to the on/off switch and that's where I got the 2.4 , same thing with the 2 fan mini cooler where I got the 2.6. *So since the TWO SEPERATE are using two USB ports does the USB HUB split the voltage between the USB ports? If only one was connected would it read 5 and the fans would spin faster?* As for the way the 3 fan USB is wired, all the red wires coming off the fans meet at one terminal on the switch and same thing with the black wires. So since all the reds go to one terminal and the black wires to the other terminal on the switch that would mean they are all connected in parallel. So what I'm going to do is take the 5 fans apart from the coolers along with the off/on switch, then run all the positives to the red terminal on the switch and all the negatives to the black terminal like they are now, but this time including the other two fans making 5 fans total. *Then all I do is connect the on/off switch to the DC plug rated at 5 volts by connecting the red and black wires to the switch just like the way the USB cable was connected and everything should be ok correct?*


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## Tomken15 (Dec 7, 2011)

I would have thought it was illegal for the fans not to have some specs on them, but if they have a wattage (w) value on them, then divide that value by the voltage and that will give the max current.

You could also make up a patch lead of similar gauge wire with a mini clip on each end and connect that between the power source and the pos lead of the fan, stick the red probe on the first clip with the neg on the other clip and with the fan wired up, will give an approximation of the current.

Wiring the same value components in parallel will allow more current to flow than they would when in series up to the fused value.

That is because there is less resistance when paralleled.


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