Hi peeps
Just in the process of finishing my scrog box, does anyone know how i should wire in a pc fan, its 12v so i know i can connect it straight into the mains circuit, do i need a 240v - 12v converter?
Any help will be greatly received
Thanks Dirk

Have heard you can use a mobile charger. Wouldnt like to try it myself though


Sure someone will be along to help soon.




Peace

DON'T TRY AND PLUG IT DIRECTLY INTO THE MAINS!

In the UK, mains is 240V AC - your fan will need 12V DC - you can buy voltage-selectable 'wall wart' power supplies for £5 or so from quite a few places, try and get one of these, 12V is usually the top voltage setting on them.

I wouldn't personally bother trying a mobile charger (or a PC fan, for that matter ), as they are mostly 4V-6V or so, which will make the fan even more pathetic than it already is.

erm.... i have 2 x 13v dc computer fans connected directly to the mains right now...

Hi
The Box using is not that big so using i larger fan is not really an option, i may search for a small fan that i can connect directly to the mains, that would be ideal.
Bought a couple of pc fans from somwhere, they are about 3inch square, are the pc fan really that feable?

Don't worry. Two of my fans are 3" and that is the 13v dc ones. I am confused as to why you say 12v and 3" as there are two types of fans you get in computers the processor cooling fan mounted onto the grill and the extraction fans which are the 3". Well my 2 fans are using the same wire going into the mains as well as i don't have much wire. It's a normall plug socket and not a charger or anything with a transformer inside. Be carefull though to remember the difference between ac and dc is that dc current travel in the oppisite direction of ac. Like say you want to put a dv fan on a ac plug. The dc wires would go on the oppisite direction.

Here i need a better way of explaining this.

Lets say we have a AC plug with wires blue and red. We have a DC fan with a red wire and a blue wire. Well to get the fan working without blowing up you would put the blue wire from the plug to the red wire on the fan and put the red wire from the plug onto the blue wire of the fan.

Remember me saying that the difference betweed AC and DC is that the currents run in the oppisite direction.

Be carefull to get this right otherwise you will end up with a blew up fan. Or a blew up face for that matter....

Hope this helps if you didn't already know it

No you have'nt!

Laws of physics break down around your way then?


If they are running on 240v ac I'd have a look at those fans closely.

I think you'll find a bit on them that says: 240v ac.


For the record,DC travels in one direction and AC back and forth,that's why its called alternating current.

Err i dont think so!!! are you sure they not 240v ac fans? PC fans require 12v dc as people have said get a universal mains adapter and splice the end off. Or use a old pc power supply and loop the on/off so it on all the time.

If i was you i would take a quick course or do some internet reading on electrical basics before you do anything else otherwise i can see a nasty little accident happening !

... How thick am i... I have a 14v adapter connected to the fans.... I forgot about that part.. :|

Agree with the good Dr. - you most definitely *don't* have a normal garden-variety 12V PC fan connected directly to the (240V 50Hz AC) UK mains - if you do, and there haven't been in the middle of some spectacular fireworks and escaping magic smoke, then they aren't common 12V PC fans.

NO! THIS IS *VERY BAD* ADVICE!

Are you trying to get someone killed, useless?

DOH!

Fair enough, but how do you explain this snippet of 'advice', then?:

Yes i can.... I was just giving an example of how AC and DC work and making sure that people understood when i said that " DC current runs in the oppisite direction of the AC" actually meant without blowing themself up.

Both these statements are very wrong - AC current alternates direction however many times a second that it's frequency in Hz is - for example, UK mains current (240V 50Hz) alternates direction 50 times a second - looks like a sine wave on a 'scope.

Click to view attachment


Both of those statements are completely wrong.

http://www.physicsforums.com/archive/index.php/t-76381.html


Maybe that will help...

Don't need to go there Dangerous,sorry I mean Useless.

NO i know that i am right. To change a adapter from ac to dc you just swap the wires over.

No matter what you may say.

Listen pal,don't go posting shite you know nothing about.

Sorry if I sound a tad angry but that's because I am.

You've posted very very dangerous advice that could have caused a newb or someone trusting enough to take your advice which may have led to electroctution or fire or damage to equipment at the very least.


You've put your hands up to making a mistake is good,but then go and still try justify your very dangerous advice!

Total bollocks - maybe *you* should read the link to that AC/DC forum post that you posted earlier. You are *so* wrong, it's untrue.

Maybe you should read it, it doesn't say anything of the kind.



Before advising others to plug DC fans directly into the mains, you should try it yourself. I know you haven't done this, because the fan would burn out immediately and quite likely catch fire.

Rarely have I seen such stupid, ignorant, downright dangerous advice.

I have an adapter here which is ac/dc. To change between ac and dc there is a little extention on the end where you just swap the end round to change it into dc or ac. Here is a pic of what it looks like.

When you swap it round you are swapping what direction the electricity goes in, inside whatever is going to be consuming the power.


No no i admit that i was wrong about that.... I said that i had an adapter onto it and it wasn't going into the mains. I forgot that i put the adapter on.

Swapping the terminals of a DC circuit over will not make it AC. AC goes in both directions, changing direction every 50th of a second. DC flows continuously in one direction, if you change the direction it flows smoothly the other way.

Your adapter may have a switch or something so that it can produce either AC or DC, but you so don't understand how it works.

Fucking hell, mate - you really don't understand about electricity, do you?

What you're talking about there is changing the *polarity* of the output, which is nothing to do with it converting AC to DC.

I am too scared to bitch....

I was only trying to help....

I will be quiet from now on...

Nobody is bitching,just trying to put the brakes on dangerous advice.

Chill mate,we all make mistakes and it was just unfortunate that what you thought was sound was potentially dangerous.


Scuse me if I don't ask you to rewire my house!

Nothing to be scared of, useless - helping people is good.


I would, however, like you to retract this statement, and I hope that you have learned something about electricity today.

easy now! this is turning into i bit of a debate! i have done a bit of research so i'm not about to go sticking the wires directly into the plug socket, its not fireworks night yet! think maybe i'll head down the the store i bought the fans from and see if i can buy a mains adapter with a viarable voltage switch so i can adjust the spped of the fan. a timer would be good too

And the debate ends now.

Just get a 'wall-wart' type power supply like the one the useless posted a picture of - like I say, you can get similar ones for about £5 from quite a few places, and it'd be ideal for what you want to do.



e2a: Not a 'debate' - more of a 'correction', I'd say.

MOD

Delete the thread before someone gets really hurt!

It looks like the only person that will get hurt is me (Which is VERY unfortunate) :S




I retract my statment.
I will say that i am more of a software guy than a hardware guy.

Handsomely done sir.

We all get it horribly wrong occasionally. Anyone would think we're all on drugs...

Nice to see your balls m8 no one was taking the piss its just us growers need to stick together and help each other out, nothing worse than trying to have a wank with 3 fingers and 1 eye because he didnt know if he was AC/DC!

Having a joke m8 take it easy and good luck with the grow!

[font="Comic Sans MS"][/font] you can buy a voltage selector adapter from any good electrical retailer
they have a connection for 9v batteries on the side
take a piece
of speaker wire and connect it to yuor fan the touch the contacts on the connector with it plugged in
dony worry!!!!! it s only small voltge!! tape the connection in place........
hey presto
i powerd 3 pc fans this way hope this helps

thanks gitc i'll give that ago

Also thanks useless, maybe not the best advice but i Know ya meant well!

Woah woah... TIME OUT!!!



Let me set the record straight with more info than anyone wants. First, useless, I think we all know that you meant the best, but.. uhm.. your advice was pretty.. uhm.. useless. I'm calling the impending fight dead.. it's in the past.. let sleeping dogs lie.. live and let live.. give peace a chance..

Okay, so you have some PC fans. They run on 12V DC (direct current), not AC (alternating current). If you were to run them on AC (let's just say for fun you had a source of 12V AC) they wouldn't do anything, they'd just flutter back and forth at 50Hz (50 times per second), that is they'd just sit and twitch like an old man with a palsy who drank too much coffee. To make them run, you need to get a source of 12 volts electricity in the form of direct current.

A good ol' car battery would do it, but it'd eventually run out of power, so a much more convenient way to get 12VDC is to use a transformer of some kind that plugs into the mains. These come in many forms, but the cheapest is probably the "wall wort" that's been mentioned and that useless posted a picture of; you can get one at any reasonably large store, in the US I'd mention WalMart, Target, or RadioShack.. I don't know where you could find one in the UK, but I'm /sure/ they're available. There are two wires that come off your average wall wort, usually one has a stripe on it and the one with the stripe is negative, so the wire with the stripe should be wired into the black wire on the fans, the wire without the stripe should go to the red wire. If it doesn't work, swap the wires around.

Another way to get 12VDC out of mains is to get an automotive battery charger, they take in mains voltage and pump out 12VDC to charge your car's battery with. These almost always have one red and one black... just match the colors up and you're good.

The other way is to use a computer power supply. A computer power supply has (essentially) 3 voltages that come off of it, 12V, 5V, and 3.3V on the Yellow, Red, and Orange wires respectively. All the wires of a particular color are the same voltage... all the yellows are 12, all the reds are 5, all the oranges are 3.3..oh and all the black wires are negative, or "ground," or maybe even "earth" if you want to call it that. If you splice the fan's red wire into one of the yellow wires and splice the fan's black wire into one of the many black wires on the power supply you'll have 12VDC running to the fan. You can turn the supply "on" by shorting the green wire (on the ATX connector) to any of the black wires.. a paper clip works well for this, and the voltage over the green wire is so low that it won't shock you or be dangerous.

Oh wow, that's longer than I expected.. I guess there's a reason I call myself Pot Geek...

Thank you Pot Geek for cutting crap, (generally) if someone has to explain electrical wire ring to you over the internet you should not be doing it, and that is not IMHO but the opinion of most coroners. On,the side of your appliance there will be a specification plate, amongst the details will be a voltage rating a number the letter V and a symbol go to a sight like one where you have to "ask" and learn those symbols. If the plate is missing or unreadable do not use (i will not tell you how to test rating). when you know the voltage buy a transformer connect to your device plug into mains and be safe IMHO the car battery charger is a safe alternative, but the PC power supply although suitable contains a lot of energy and should only be used if you really know what you are doing,scalelctrix, model railway, phone or other transformers may be suitable they also will have a spec plate if you understand it and it says the same as your fan and you are sure, use it, any doubt buy a transformer. Another useful number on spec plate is the wattage which if understood will allow you to set more efficient fuses and spread you power demands more evenly. Size of fan is not necessarily important a small fan running at high speed can give same volume movement has bigger fan revolving slower. I can not help you with makes as I run 2 old Hover motors whose speed I control with IC ><%"£555 and I transform my elect&^%$*> 960 turns"!¬*other ~:@£^ turns Wheatstone bridge &%$ rectification (if you got that I may swap circuit diagrams with you) else buy a transformer.
Have a nice life.

just like to say thanx for blowing my whole electrics to my house USELESS! only kidding m8 well done for admittin u wer wrong tho reading through it i was getting more and more concerned for ur safety i must say, guess i care to much eh? well now all is understood and we all understand why uve called urself useless nah seriously its not easy admittin ur completely wrong and it makes u feel pea size so fair play




smokes