# Fridge Fan



## vicdicdoc (May 14, 2005)

Anyone who knows me, knows I dislike paying out good dosh for something that can be 'home made' . . . my latest project is a 2 speed fan for the rear of the fridge [ready for the boiling hot weather :? ], I'm using a small computer fan, double pole switch and a pair of different coloured 12v LED's to show when the fan is switched to 'fast' or 'slow' . . . 
try as I have, I can't get my head around the circuit so that the green LED lights up when its set to 'slow' and a yellow LED for when its switched to 'fast', everything works ok - except that BOTH LED's light up when on either fast or slow.
The fan has 3 wires [Red, Yellow & Blue]. [Red & yellow = slow / Red & Blue = fast]
12v feed is shown as red & Blue
What am I doing wrong [except not buying a ready made unit] ?
I've 'drawn' a diagram . . . would anyone care to look and amend it to show where the wires from each LED should be soldered so it works correctly.
[Red = positive, Blue = Neg from the power source.
Red = live feed to the fan.
Yellow = 'slow' feed to the fan.
Blue = 'fast' feed to the fan.

If you follow my meaning :?


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## doug285 (Apr 30, 2008)

I could be well and truly shot down here as electrics are not my strong point, but in my opinion you have the switch wired incorrectly. As it is I would have thought that the fan only works on fast speed anyway. If you were to connect the live feed to the switch(red) rather than the blue, (the blue being the return) then solder one LED between the yellow(the yellow being your half speed feed) and blue, and the other to the red and blue,(red being your full speed feed) then you may have more success.

Apologies if I am wrong here, but at this time of night I could well be. :?


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## sallytrafic (Jan 17, 2006)

Vicdicdoc

No unlike doug I think your fan wiring OK the problem is that inside the fan the two speed wiring is connected together something like my first diagram so although the power is not say on the fast one there will be a connection through its circuit from the slow feed and current will flow through the LED.

If the internal fan circuit was like my second diagram then your LEDs would have worked.

Current sensing through the feed wires rather than the simpler voltage sensing would work but electronics needed.


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## mangothemadmonk (Aug 6, 2006)

Vic, why dont you just buy one for £29? It comes with two speed, two fans, thermostat, all wired up ready and a nice front with leds and switches etc...

Have a look Here.

Get that FS pension spent mate :wink: :wink: :wink:

Johnny F


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## pippin (Nov 15, 2007)

I have used two fans but employ a different method to get slow speed.

I have ignored the third wire in the fans and just cut them off.

I use a double pole changeover switch with centre off position.

One position has the fans wired in parallel across 12V. Both full speed.

The other wires them in series so that they run at half speed as each has only 6V across it.

It would be relatively simple to have LED indicators but I see no need.

If I knew how to draw cct diagrams by computer and post them on here then I would do so, but I don't, so I can't!


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## 107558 (Oct 10, 2007)

If you are using a computer fan one of the wires maybe a speed sensor rather than a "live".


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## AberdeenAngus (Jul 26, 2008)

Use a double pole, double throw (DTDT) switch, & drive your led's off the spare contacts.

Even better, get a DPDT with Centre off, then you can have Fast, Slow or Off...

Don't forget about resistors for your led's.

Without them your led's will work just fine but only for a really, really, short time !!


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## CliveMott (Mar 10, 2008)

The problem is that when you power one wire of the fan a voltage will always appear at the other wire.
Here are a couple of solutions.
Oh yes, 
The switch you have drawn is a SINGLE POLE change over.

C.


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## spindrifter (Nov 14, 2006)

Vento Fan Kit

I fitted it last week. Top bit of kit - easy to fit. Comes complete except for a 1.5amp fuse and holder. No faffing about job done in 2 hours.

Cheers

David...............(Spindrifter)


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## CliveMott (Mar 10, 2008)

Has anybody thought of connecting the fan directly to the output of the solar panel? When the sun shines the fan runs - just when you need it.
At night the fan is off. Hazy day = slow fan. 
(you will need a voltage regulator for the fan to limit the volts to a safe level)

?????
C.


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## spykal (May 9, 2005)

Hi Vic

I do like reading about your homebuilds :wink: so do keep at it, and reporting :wink: but unless you are off to places where 35- 40C is common do you actually need the fans? In my van I have improved the cooling of my fridge just by improving the venting. The two outside vents effectively open into a space that contains the back of the fridge with the burner and cooling tubes and also a large open space above the fridge. All I have done is to arrange a deflector at the top that helps the natural airflow to enter the bottom vent and flow smoothly out of the top vent. 

Mike


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## vicdicdoc (May 14, 2005)

Oh S*** . . I just knew my electrical ability was ziltch :? 
Many thanks for your combined advice . . I'll go back to the drawing board and 're-design' it.

JohnnyF . . I'm saving my pension to pay for diesel :wink:

Clive, 
The switch I have does have 6 connections in 2 rows of 3 [but for 'clarity' on my diagram I only drew 3]. 
On your diagram [version 2] I think I follow your wiring . . . I never thought to try the LED's across the other set of 3 switch connections ! 
-so, to be clear - each 'set' of 2 connections are inter-connected inside the switch [?] and using [as you have numbered them] No.4 as the slow, No.6 as the fast and No.5 as the negitive feed, I can then use connection No.1 for the 'slow' LED and No.3 for the 'fast' LED with connection No. 2 being the negative ??? 
Another trip to Maplins in the order of the day !

[Agreed, I'll prob end up spending a couple more quid but I love the satisfaction of actually making something work !]


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## CliveMott (Mar 10, 2008)

Hi Doc,
The only connections between the two sets of 3 contacts is mechanical. the two switches operate in unison. There is no electrical connection between the two sets inside the switch.

Hope that helps.
C.


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## vicdicdoc (May 14, 2005)

spykal said:


> : . . . but unless you are off to places where 35- 40C is common do you actually need the fans? In my van I have improved the cooling of my fridge just by improving the venting. The two outside vents effectively open into a space that contains the back of the fridge with the burner and cooling tubes and also a large open space above the fridge. All I have done is to arrange a deflector at the top that helps the natural airflow to enter the bottom vent and flow smoothly out of the top vent.
> Mike


Mike,
My cooling vent inlet is from below the van and the outlet is up near roof height so I'm thinking of fitting the fan inside the upper outlet vent [see my wonderful drawing :?


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## vicdicdoc (May 14, 2005)

CliveMott said:


> Has anybody thought of connecting the fan directly to the output of the solar panel? When the sun shines the fan runs - just when you need it.
> At night the fan is off. Hazy day = slow fan.
> (you will need a voltage regulator for the fan to limit the volts to a safe level) ????? C.


Dah . . wish I'd thought of that solution


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## vicdicdoc (May 14, 2005)

I've just though of my NEXT project . . . a small lightweight unit to convert urine into Hydrogen to run my van :wink: [should be simple as I've already got a couple of empty jam jars :idea:


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## Zebedee (Oct 3, 2007)

vicdicdoc said:


> I've just though of my NEXT project . . . a small lightweight unit to convert urine into Hydrogen to run my van :wink: [should be simple as I've already got a couple of empty jam jars :idea:


And Mrs Zeb says I'm full of the other Vic, so I see a partnership developing!!


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## Texas (May 9, 2005)

Although my fridge is isolated from the rest of the van...as per John Wickersham manual and has a cowling to direct the hot air out of the top vent, I've had 2 fans fitted to the top vent of my fridge for the last 5 years.

They cost £3.99 off ebay and have a gizmo built in that allows them to run: stop, slow through to fast depending on the air temp over the fridge fins. 
They are extremely quiet in operation, so quiet in fact that I sometimes have to go outside and feel if there is air being blown out - would make a good hair drier.

They are wired through a switch off the leisure battery so that they can be turned off if need be, and work superbly efficiently.

Texas


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## spykal (May 9, 2005)

vicdicdoc said:


> CliveMott said:
> 
> 
> > Has anybody thought of connecting the fan directly to the output of the solar panel? When the sun shines the fan runs - just when you need it.
> ...


I like that idea... just for a laugh I bought a baseball cap with a solar panel on the top and a fan in the peak ... well it really works ...so maybe I can feel a "solar baseball cap conversion to fridge fan" project coming on :lol:

and Vic ...I can see that your tall vent is a different to mine ... so here is another idea to chew over ... your top vent is way up ...that maybe gives you the opportunity to turn it into a flue... the shape of a chimney is often restricted towards the top to increase the flow speed of the rising gasses... which in turn draws more air in at the bottom ... I wonder could you use that principle to make the cooling work more efficiently?

Mike


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## spindrifter (Nov 14, 2006)

Hey. How about fitting a duct from the cooker hood extractor fan to the fridge vent. Then you could cook and cool all in one go!!! If that worked you could extend the ducting to the engine manifold thus having a super charger on the engine. If that worked to could fit the ducting to a heat exchanger...................................

Blimey - I've gotta cool off now.... on the other hand I could fit the ducting............................

David (Spindrifter)


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## AberdeenAngus (Jul 26, 2008)

vicdicdoc said:


> I've just though of my NEXT project . . . a small lightweight unit to convert urine into Hydrogen to run my van :wink: [should be simple as I've already got a couple of empty jam jars :idea:


don't you start too !!!!!


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## vicdicdoc (May 14, 2005)

spykal said:


> . . . I can see that your tall vent is a different to mine ... so here is another idea to chew over ... your top vent is way up ...that maybe gives you the opportunity to turn it into a flue... the shape of a chimney is often restricted towards the top to increase the flow speed of the rising gasses... which in turn draws more air in at the bottom ... I wonder could you use that principle to make the cooling work more efficiently?
> Mike


. . . I could of course avoid any hot climates - but that would mean moving out of Wales :wink:


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## krull (Jul 22, 2006)

THE YELLOW WIRE IS A SPEED SENSOR, NOT A SLOW SPEED POSITIVE-CUT IT OFF

If you want hi/lo speed, buy a Maplins Ultra quiet fan. It comes with a resistor that cuts done the speed to make it silent. If you want a hi/lo switch, simply use a switch to bypass this resistor.

This is how I have done mine.

I actually used a dpdt 3 position switch: middle position =off, up=High, down=Low

Fan:
http://www.maplin.co.uk/Module.aspx?ModuleNo=32309&C=Maplin&U=SearchTop&T=ultra quiet fan&doy=9m8

Switch (Type F):
http://www.maplin.co.uk/Module.aspx?ModuleNo=2341&C=Maplin&U=SearchTop&T=dpdt switch&doy=27m7


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## vicdicdoc (May 14, 2005)

krull said:


> THE YELLOW WIRE IS A SPEED SENSOR, NOT A SLOW SPEED POSITIVE-CUT IT OFF
> If you want hi/lo speed, buy a Maplins Ultra quiet fan. It comes with a resistor that cuts done the speed to make it silent. If you want a hi/lo switch, simply use a switch to bypass this resistor.
> This is how I have done mine.
> I actually used a dpdt 3 position switch: middle position =off, up=High, down=Low
> ...


These are exactly the items I've bought, thanks to Clive & others, I've now sussed it out and Mk2 is well on the way to being complete [MK1 was the 'prototype' . . in other words - I soldered the LED's on wrong 
:? 
Mk2 is the bee's knee's or should that be the cat's whiskers, anyway it all works as I intended . . now thinking about the Urine to Hydrogen fuel cell :wink:


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## Zebedee (Oct 3, 2007)

vicdicdoc said:


> . . now thinking about the Urine to Hydrogen fuel cell :wink:


Just don't forget who your partner is!

Mrs Zeb confirmed my qualifications again today - "_All hiss and wind_".

I think that's what she said? :lol: :lol: :lol:


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## mangothemadmonk (Aug 6, 2006)

Vic, I think Zeb is just taking the p**s :wink: :wink: :wink: :lol: :lol: :lol: 

Johnny F


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## Zebedee (Oct 3, 2007)

mangothemadmonk said:


> Vic, I think Zeb is just taking the p**s :wink: :wink: :wink: :lol: :lol: :lol:
> 
> Johnny F


Who . . .me!! 8O 8O 8O 8O

I was merely offering to supply Vic with an essential commodity of which Mrs Zeb assures me there is a generous surplus available for immediate disposal.

If he could arrange for a tap to be gently trickling into a bowl of water nearby, the transfer of said commodity from my storage vessel into his chosen receptacle (I recommend a porcelain container) would be significantly expedited.

Straightforward business arrangement!! :wink:

Hiss off Mango, with your feeble attempt at industrial sabotage. We're onto a winner here! :lol: :lol: :lol: :lol:


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## pneumatician (May 1, 2005)

*Van Fuel*

Following the string created by Vicdoc & Zeb.
As I understand it during the war vehicles ran on Chicken sh*t or the methane produced. A large gas bag fastened to the roof of the vehicle contained the methane.
According to our club groundsman Canada Geese are the best Sh*te machines currently available.

So carry X number of Canada Geese in a trailer. Stop at a grazing site. Let them graze overnight and convert existing trailer contents. In the morning transfer to the Gas bag. Then move on to the next stop and grazing site. An additional benefit would be the ready source of protein in the Geese and Eggs.

I think Zeb might remember the war system so he could perhaps suggest how many geese to run a 2.8L engine. :?

An aside when do we start booking for Amboise 2009. 

Steve


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## Zebedee (Oct 3, 2007)

*Re: Van Fuel*



pneumatician said:


> I think Zeb might remember the war system so he could perhaps suggest how many geese to run a 2.8L engine. :?
> Steve


Sorry Steve, I'm wise beyond my years. I was a war baby.

Better be careful or those pesky Mods will be after us for wrecking the thread!!    :lol: :lol: :lol:


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## spykal (May 9, 2005)

Hi

If Vic's scheme works the "Taking the P***" may yet again become an industry.

If you have visited the Alum works at Ravenscar < near Robin Hoods Bay you will already know about this activity <<<...

If you haven't then do go there ...it is nice part of the country. Sorry that was a bit {offtopic}.

Mike

P.S. some of the best threads are rambling ones :wink:


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