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Fan Header Question: Volts, Amps & Watts Multiplication & Multiple fans...

Minder

Apr 24, 2015
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What you need to do is forget about the fans, study up on Ohms law and the relationship between Volts, amps, wattage first.
There are some basic deficiencies in your thinking, 20 posts later all have been trying to explain it to you.
M.
 

JunkRoom

Jul 11, 2015
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What you need to do is forget about the fans, study up on Ohms law and the relationship between Volts, amps, wattage first.
There are some basic deficiencies in your thinking, 20 posts later all have been trying to explain it to you.
M.
Absolutely I'm assuming the problem is with my understanding rather than with the laws of physics and I thought it should be a trivial matter to post to an electronics forum and get help with it rather than be told to go read a book. :shrug:

And I'm sorry but I don't think anyone's actively been trying to explain any of this to me. It seems the clearest and most concrete examples have been posted by me and that no one even seems to understand the questions I'm asking. I'm trying to clarify to the forum what it is I'm confused with but unfortunately it seems to no avail.

I've even got a moderator calling me a dumb-ass because as he sees it I don't seem to understand what it is I've been trying to impress upon the people here. :shrug:
 

garublador

Oct 14, 2014
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Absolutely I'm assuming the problem is with my understanding rather than with the laws of physics and I thought it should be a trivial matter to post to an electronics forum and get help with it rather than be told to go read a book. :shrug:
I think that most of us try to avoid duplicating information, especially when it's the type of information that's repeated in many, many resources. If you aren't getting it out of a book (or website or whatever), you'll just be getting the same information from someone on here. Apparently no one is willing to duplicate that information for you in this thread when it's available so many other places.

The short answer is that that's not how parallel circuits act. That answer has been given many times. The long answer either requires a book or someone reproducing the contents of that book here. It's the same for you either way but a lot of typing for someone trying to re write what's already been written very well many times over.
 

Martaine2005

May 12, 2015
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Hey junkroom,
I have been reading this thread and have come to the conclusion that you suffer with Martinsyndrome!
Hi, I am Martin and cannot explain myself very well or understand the obvious when it's dished up on a plate either!!

Let us laymen chat!!!!
The fans are 12v..Right?...original fan consumes 0.21A...right?
If you wire the fans in parallel (positive to positive) And (negative to negative), the fans are only running on 12V....ie, a splitter, header etc....

If you put two identical fans of 0.21A, they will draw twice the current.
So what you need is two 12V fans at half the current rating of the original fan!

Martin
 

davenn

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Sep 5, 2009
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I thought it should be a trivial matter to post to an electronics forum and get help with it

and it has been explained to you, clearly several times

And I'm sorry but I don't think anyone's actively been trying to explain any of this to me.

That is an incredibly incorrect and unfair statement

what I laid out a few posts ago is VERY plain


lets start again

read very carefully what I post and state VERY clearly which parts you don't understand

Power ( watts) = V ( Volts) x A (Amps)

your the existing fan is 12V @ 0.21A = 2.52W

you add another fan to the same 12V supply ( there is NO 24V there , never has been never will be)

the second fan ALSO draws 0.21A from the power supply

so the 2 fans are drawing 0.42 A from the 12V power supply

P = V x A
P = 12V x 0.42 A
P = 5.04 Watts


Dave
 

JunkRoom

Jul 11, 2015
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I think that most of us try to avoid duplicating information, especially when it's the type of information that's repeated in many, many resources.
I appreciate your optimism, I really do but it's not something I can share with you. I didn't come here for an argument, I just came here for a little clarification and am just more confused.

Martaine2005 thanks.

and it has been explained to you, clearly several times



That is an incredibly incorrect and unfair statement

what I laid out a few posts ago is VERY plain


lets start again

read very carefully what I post and state VERY clearly which parts you don't understand

Power ( watts) = V ( Volts) x A (Amps)

your the existing fan is 12V @ 0.21A = 2.52W

you add another fan to the same 12V supply ( there is NO 24V there , never has been never will be)

the second fan ALSO draws 0.21A from the power supply

so the 2 fans are drawing 0.42 A from the 12V power supply

P = V x A
P = 12V x 0.42 A
P = 5.04 Watts


Dave
Dave I appreciate your trying to help and I'm guessing you'll think I'm probably just trying to be awkward but you've misread me. What you've written there is an incorrect summary of what I've written.
 

davenn

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What you've written there is an incorrect summary of what I've written.

so why do you think it is incorrect ?
explain clearly ... don't just tell me something is incorrect without an explaination !!
 

JunkRoom

Jul 11, 2015
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so why do you think it is incorrect ?
explain clearly ... don't just tell me something is incorrect without an explaination !!

I was going to try and offer more information but it just seems pointless at this point. This situation has deteriorated to the point of it seemingly not being redeemable.

The error is that my intention was to replace the 12V 0.21A fan with two new 12V fans that drew 0.21A when combined. The original fan was to be discarded.
 

davenn

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t sure where this should be posted so I've posted it to general discussion.

I want to use a fan-splitter to replace a single fan with two new ones.

The fan I've removed is 12V and 0.21A.

Assuming the header can support a fan of 12V and 0.21A:

Can I replace that fan with two 12V fans totaling 0.21A and not risk burning out the header, or will the wattage be too high?

E.G.

One fan of 12V and 0.11A + one fan of 12V and 0.10A equaling a total of 0.21A...


OK just seen something in your first post ... hey I was up all night photographing the Geminid meteor shower :rolleyes: only had 2 hrs sleep
I apologise for misreading

looks like we all got thrown off by the example you followed with towards the end of your first post

OK so the 2 replacement fans are totalling the same current as the single old fan

OK so no problem just do it, put them in parallel so each one sees 12V .... job done
 

JunkRoom

Jul 11, 2015
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OK just seen something in your first post ... hey I was up all night photographing the Geminid meteor shower :rolleyes: only had 2 hrs sleep
I apologise for misreading

looks like we all got thrown off by the example you followed with towards the end of your first post

OK so the 2 replacement fans are totally the same current as the single old fan

OK so no problem just do it, put them in parallel so each one sees 12V .... job done

Thanks. My confusion was that it seemed to increase the wattage even with the same amperage because there were two 12V fans. That's what's confusing me. I think it should be the current I'm worried about but while the current seems fine the wattage seems to increase. I'm not sure if it's my math or my reasoning, I just thought I could get some clarification.

P.S. No worries, I know full well what lack of sleep can do to a person :)
 

JunkRoom

Jul 11, 2015
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Thanks. My confusion was that it seemed to increase the wattage even with the same amperage because there were two 12V fans. That's what's confusing me. I think it should be the current I'm worried about but while the current seems fine the wattage seems to increase. I'm not sure if it's my math or my reasoning, I just thought I could get some clarification.

P.S. No worries, I know full well what lack of sleep can do to a person :)
That bit in red is the bit WE ALL missed


D
Apologies, I thought that was clear :/

Sorry - double post. I hit reply instead of edit.
 

davenn

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I think it should be the current I'm worried about but while the current seems fine the wattage seems to increase.

neither increases as the combined currents of the 2 fans is equal to the current of the single old fan :)

so nothing has changed



D
 

davenn

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Apologies, I thought that was clear :/

Sorry - double post. I hit reply instead of edit.


no probs
we got there in the end :)
I got home and to bed from my astro photos session at 430am, the alarm went off at 6.15am. Im at work now and my brain is a little mushy haha


D
 

JunkRoom

Jul 11, 2015
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Apologies, I thought that was clear :/
neither increases as the combined currents of the 2 fans is equal to the current of the single old fan :)

so nothing has changed



D

Thanks, for clearing that up for me. I'm not sure how I got that mixed up. When it comes to numbers my logic is next to useless. I don't know why, it just seems to be the way it is for me. The more I train it the better it seems to get in every area but math.

Sorry about that.

no probs
we got there in the end :)
I got home and to bed from my astro photos session at 430am, the alarm went off at 6.15am. Im at work now and my brain is a little mushy haha


D
Are you going to post the photos to the forum? It'd be interesting to see.
 

Martaine2005

May 12, 2015
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Thanks, for clearing that up for me. I'm not sure how I got that mixed up. When it comes to numbers my logic is next to useless. I don't know why, it just seems to be the way it is for me. The more I train it the better it seems to get in every area but math.
I hear ya bro!!:p

Martin
 
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