All,
Im trying to install a 12v 8.0 amp fan in the window of my car
to keep my dogs cool while Im away for short periods of time
Thats the general goal.

I used a variable speed fan circuit like this for a project some time ago
can it be adapted or modified to work in my scenerio?

Voltage:12v DC
Fan 12 DC fan
Draw: 8.0Amps


here is the old circuit. (worked for a 5V fan)

 

In most states even with a fan you can have more trouble than
you really want.People react more to pets than humans (PETA)
to hot unattended cars. I surprised that you have not seen or heard
these stories,for death people do hard time.

 

I have a friend who shows dogs and has little fans that she puts on their crates while in the car. She claims they work. I don't believe it...I have a pug, and I really love driving around with him, but in the summertime, he stays home unless he can go in with me where I am going. It would seem that a fan would just blow the hot air around. Just my two cents. It is a nifty idea.

 

Dogs like air blown in their face even if it's hot air.

 

This fan project is the direct result of almost getting arrested.
I travel almost everywhere with my dogs. their like my kids (since I dont have any) anyways an ignorant Police officer threatened me, spoke to me like I was
a 5 year old, nothing I could say was right... we all know the type. and if you dont? well then you had better hope you dont run into this one.
hes the one who gives your local law enforcement a BAD name....

anyways I wont rant much more... Im still determined to be able to travel with my dogs. I looked up the local ordinance regarding my scenario.
all I need is an FAN. Ive already built it. (I can upload pics) And it came out quite nice. it has an On/Off, Built in thermostat and Reversing switch.
But Id like to make the fan variable speed off when not needed. and variable
up to full speed when hot. like my PC fan does with the above circuit.

 

What's with cops and animals

i was driving down the road last week,,this damned cat ran in front of me
so we all know what happened - and just after the collision, and the "squish" sound i did what any normal person would do, kept going.
not more then 20 seconds later, wooooooooooooooooo,,woooooooooooo,,cops!
well,, the ass walked up, said, did ya know ya ran over a cat?
i was like, ummmm, that wasnt a pothole??

nope he said,

and like most $##$&***%#@@ cops,,said, alright, ya need to go around to these houses and find out if it was their cat,,
heh,,so off i went,,
bout the 8th house i went to,,(of course) this old lady answered,,
i asked if she owned an orange tabby cat,,,she says yes i do,,,( of FRIGGIN course)
so i told her what happened,,and as my luck goes she started crying n looking all old n stuff,
so i took $20 outta my pocket and told her to buy a new cat if she wished,
i turn round, there's that friggin cop standing there behind me,,
i say,,"freakin happy now?"
and the cop walks over to the old lady and places her under arrest.
i was freaking out, asked the cop what ta f!!
he says , "well she's under arrest"
i said "ya i figured that out smartass","what ta hell for!!!"
"selling pussy " he said

 

To be honest I do not think a fan will help much if it is hot outside. You need AC, not a fan. On a hot day the dog will have it much better in your house. You should also use PWM like I mentioned here
http://forum.allaboutcircuits.com/showthread.php?t=26502

 

To be honest I do not think a fan will help much if it is hot outside. You need AC, not a fan. On a hot day the dog will have it much better in your house. You should also use PWM like I mentioned here
http://forum.allaboutcircuits.com/showthread.php?t=26502

could someone supply a schematic/parts list.
Ive seen other PWM's but I did not know if 8.0 amps was within the limits
Also is this just a manual controller for output voltage or would this also
have some kind of thermistor that could control the speed?

TIA..

 

To be honest I do not think a fan will help much if it is hot outside. You need AC, not a fan. On a hot day the dog will have it much better in your house. You should also use PWM like I mentioned here
http://forum.allaboutcircuits.com/showthread.php?t=26502

Forgot to mention yes AC is the right solution... But the law here in Tampa bay says. "An exchange of air" Its also against the law to leave your vehicle running unattended. here tin Tampabay. unless of course your the LAW.

 

A 555 timer and a N channel FET should be something to get you started. Do a search in this forum. Try also Goggle and "pwm n fet 555 timer" Are you going to push air into your car or draw it out. In order to get circulation. The air should have easy access in and out. A parked car can be quite airtight

 

My first suggestion would be to leave the dogs at home.

Secondly if you are like my wife and have to take the dogs with then I would suggest looking into using the car's built-in blower fan(s) instead. It is installed already, a minor wiring operation to a power switch could leave it running, and it won't draw so much current, and you can just leave the windows open 30mm or so for good circulation.

 

Even with a fan blowing, the car is going to get hot in Florida! I leave mine at home during the daytime. You should also consider having plenty of fresh water available, since dogs can only remove excess heat through their mouth (obviously a swim pool is a little much, although I once consider the bed of my truck...). Seriously though, leaving a dog or kid in a hot car is risky. Fans work a little for people, because we sweat, and moving air helps it evaporate. Dogs don't sweat, and they are built to retain heat. Think about this, your battery dies, your friend dies, is it really worth it?

 

All I really appreciate the comments,
I think the first rule is common sense. But in all actuality.
The first rule is the "LAW" I learned this the hard way. mr so called a?s h?le cop
basically brow beat me. no matter what I said I was wrong.
I asked him If he had or owned a dog... he said never.... Im 45 and have owned many dogs. None of them have I ever beat or hit they have all lived long happy lives. I own 2 right now they are both chipped and tagged etc.. DO I sound like some one who has not tried to think ahead? (I ask is your pet chipped tagged taken to the dog park several times a week? )Is part of my freedom having to include proof I Love/take care of my dogs to some ignorant know it all cop? that doest even own a friggen pet? soon Ill have to explain my self when I "think"

Im sure their are some of you who think their are no "BAD cops" well I have one thing to say about that... WAKE UP. anyways this is not the forum for evaluating who is responsible enough to own a pet. How many people do you know trying to make their car safer in the event? How many K-9 units do you see with dogs in the back? My close friend is a TPD and has a German shepard/K-9 Only the Police can leave a dog in a car to suffer. and again my goal is not to have my dogs suffer. hence the reason I am trying to build a safer enviroment. User "Fanie" And yes I agree the Fan blowing is def a plus.... but mr Know it all COP said it was not acceptable. So I have this HUGE 1250 CFM Fan now hanging in my window. even in 100 degree weather its generating some
coolness via the wind chill factor.

Funny how one has to defend knowledge... but only in the face of stupidity.

 

I know my dogs...
I dont know electronics..
anyone that wants to help me help my dogs is welcome to respond to my first question.
Is their a way to adapt the circuit or a new circuit design

to run a 12 v fan that pulls max 8 amps? that is
Speed controlled by the air temperature.

Oh and sorry if I went off on a rant. I love may dogs and take their well being very seriously. No offense intended.
any helpers?

 

In most states even with a fan you can have more trouble than
you really want.People react more to pets than humans (PETA)
to hot unattended cars. I surprised that you have not seen or heard
these stories,for death people do hard time.

Very well put! And, I have heard many stories.
Just a month ago a lady left her dog in her car while shopping for 3+ hours here in Tampa the dog nearly died. she left her windows all the way up... No water. (BTW, this is not me or my style. )

 

I have a friend who shows dogs and has little fans that she puts on their crates while in the car. She claims they work. I don't believe it...I have a pug, and I really love driving around with him, but in the summertime, he stays home unless he can go in with me where I am going. It would seem that a fan would just blow the hot air around. Just my two cents. It is a nifty idea.

I thought about the little fans... but In my evaluation all they bring to the table is air recirculation and very very little of it. if the air is 90 inside. they move so little air that its not even noticeable. If your hot... which fan do you stand under. the little battery powered fan or the big honking hurricane fan? Its a shame the little ones wont work. I would never trust my dogs under one of those. thanks for the post though

 

Dogs like air blown in their face even if it's hot air.

If I lived in alaska. this would not even be an issue. can you send some cold air down here?

 

Cops around here leave their cars running, even without dogs in them, guess so the glaze doesn't melt of the doughnuts. I've only owned large breed dogs, so maybe little ankle-biters handle the heat better. I don't even take mine out when the sun is out, and over 85 degrees. I wait until the sun goes down. We go for about 30 minute walks, twice a day. No chip, no vets, last one lived 12 years, which isn't bad for such a large dog (rottweiler mix). My Lab, is a 2 year old puppy, plays a little rough for a dog park yet. Would never put them at risk for anything. Home isn't a bad place, plus I don't have to worry about thieves. The last one would have made a bloody mess, the new one... probably attempted sodomy.

 

Cops around here leave their cars running, even without dogs in them, guess so the glaze doesn't melt of the doughnuts. I've only owned large breed dogs, so maybe little ankle-biters handle the heat better. I don't even take mine out when the sun is out, and over 85 degrees. I wait until the sun goes down. We go for about 30 minute walks, twice a day. No chip, no vets, last one lived 12 years, which isn't bad for such a large dog (rottweiler mix). My Lab, is a 2 year old puppy, plays a little rough for a dog park yet. Would never put them at risk for anything. Home isn't a bad place, plus I don't have to worry about thieves. The last one would have made a bloody mess, the new one... probably attempted sodomy.

HarveyH42,
Our dogs will actually sit and wait in our vehicles all day if they could.
Their Schipperkes and weigh in around 15lbs in a fenced in area. we can leave the car door open and they will sit in the car endlessly waiting for the chance to go anywhere. mostly the Dog park. Im self employed and lots of my clients have dogs too some even take them to work with them. If I arrive without my dogs. I catch hell from them since they want the dogs to play whilst I work. etc.. I amazed at the lack of common sense people have for general safety. whether it be for dogs or heck even people.
My ride is a 4 door full size truck with a sunroof. just the sunroof alone allows for the natural flow of heat to escape the cab area. this coupled with
the windows down is even better. and once I add a fan it will be even better.
just imagine rolling at 20Mph... with your windows down... this is about the amount of air this thing can generate if needed. Perhaps I can patent it and we can all get rich? Ill have to post some pics its quite impressive.

 

I actually think this will work much better than your big fan (which is just nonsense). But as for all AC units the windows has to be closed
http://www.youtube.com/watch?v=ERWaztJdzLQ&NR=1, and it is a strange product
http://www.youtube.com/watch?v=ERWaztJdzLQ