Jump to content
  • RECEIVE THE GIFTS MEMBERS SHARE WITH YOU HERE...THEN...CREATE SOMETHING TO ENCHANT OTHERS THAT YOU WANT TO SHARE

    You know what we all love...

    When you enchant people, you fill them with delight and yourself in return. Have Fun!!!

Sign in to follow this  
DuluthMedic

12 volt fan question

Recommended Posts

I'd like to run 3 12 volt computer fans in my ice house. There called "muffin fans." I'd like to slow or control the speed of the fan. They are just too loud. I was told I needed a rheostat to slow the speed of the fan. I was also told to try an old switch from a car dashboard heater. They will all be hooked up to a boat battery. Any ideas?...I know I'm not the only one with these fans. Please help!

Share this post


Link to post
Share on other sites

Hmmm all the salvaged computer fans I've used were quiet enough as-is. Any way I think a regular 110V dimmer switch from Menards would work ok.

Another approach would to be to hook up the fans in series (+ wire of the first fan to the battery, - wire to the + wire of the 2nd fan, - wire of the 2nd to the plus of the 3rd and - of the 3rd back to the battery this would cut the speed of all three down to 1/3 (only 2 fans hooked in series would cut the speed of both in half).

The fan control from a car will work, the resistor block that goes with the switch is designed for a much heavier current draw motor than a muffin fan. What you'll get is full speed and some other speeds that may be perfect or still to fast.

A more elegant solution would be a variable resistor (AKA a potentiometer) from Radio shack or Axeman, but will require some calculations to get the right size. On the fan there should be a lable with the current draw of just the fan, probably in Amps and probably less than 1 (.05 to .3 is normal)some are listed in milliamps (.001 Amp) My example will use Amps. Divide 12 volts by the current listed on the fan let's say .1 amp and you get 120 which will be the resistance of the fan in ohms. The next step is to divide 13.2 volts (nominal battery voltage)by 120 ohms gives us .11 amps which we multiply 13.2 volts to get 1.452 watts. Potentiometers (Pots) will be rated for ohms and watts, you will need a pot with more watt rating than the fan and 1 to 3 or 4 times as much resistance - 1x the resistance will give roughly full to half fan speed. You wont find a 120 ohm pot but you might find a 500 of 1000 rated at 1.5 or better yet 2 watts. either of which would make this example fan variable from full down to probably stall speed. Run the power from the battery through a fan then throught the pot and back to the battery - Don't forget a fuse near the battery.

Share this post


Link to post
Share on other sites

I have a 8" fan (to actually move some air) and hooked it to a dimmer switch I bought off of HSOList

Share this post


Link to post
Share on other sites

ok...was it a regular 12 volt "light" dimmer switch? Or was it designed for a fan? Or won't it matter. I spoke with a person on hsolist about a dimmer switch they were selling and they said they hooked it up to a 12 volt fan and it got really hot really fast.

Share this post


Link to post
Share on other sites

I also wanted to be able to control the fan speed in my shack so I went with 120v fans and control them with a fan speed control that is normally used for a ceiling fan in a house. It works very well. I power the fans from an inverter.

Share this post


Link to post
Share on other sites

Medic - Sorry I should have specified it was a dome light dimmer switch off of a 1990 Dodge Colt.

Share this post


Link to post
Share on other sites

DuluthMedic, I think I'd have to agree with the person you spoke with. The suggestions of the house dimmer switch are good, BUT... those switches aren't heavy enough to handle the DC amps from the battery. I'd go to an Auto parts store, explain what you're trying to do, and get a headlight switch with a rheostat in/on it. That won't heat up so fast and you should be able to control the fan speed from full out to being able to count the blade revolutions. Phred52

Share this post


Link to post
Share on other sites

Hey thanks fellas, I knew i'd get a good answer here! I'm thinking of trying a junk yard for a dimmer switch out of a car/truck. I'll let ya know how it goes.....thanks again!

Share this post


Link to post
Share on other sites

Junk yard is a good idea - I went to every radio shack, auto parts store, EVERYWHERE and could not find one. The junk yard would be a good option.

Share this post


Link to post
Share on other sites

I would also suggest when you hook up the power sources for the fan to run the power wire to the fan, and use the rheostat to control the ground. This will make the rheostat last a lot longer because you are running it after the load(fan) in the circuit. By doing this with regular toggle switches, you can get by with the lower amperage rated ones because the load is before the switch and the switch doesn't have to carry the full amperage to the load source.

Share this post


Link to post
Share on other sites

Another option would be to use a few diodes in series. Or if you experimented with a variable power supply to find the optimum voltage you could use a single zener diode. Diodes pass DC current with one polarity and block it with the reverse. When the positive is connected to the anode (the wide part of the arrow symbol on the diode >| )current will pass but each diode will drop .6Vdc. So if you needed about 10Vdc you could put (3) diodes in series with the load. 12-.6-.6-.6=10.2 The .6Vdc voltage drop will be constant regardless of the load so you could put multiple fans to this circuit with out having to re-adjust the rheostat in the previous posts. The diodes won't heat up like a rheostat (which is a potentiometer with the wiper terminal hooked to one of the other two terminals to make a variable resistor)and they could be soldered to one of the power leads and not needing anything to mount the rheostat in. This would be much cheaper than a rheostat, also not dangerous if the rheostat wattage is undersized.

(Pos+)------->|-->|-->|-------FAN--------(Neg-)

Share this post


Link to post
Share on other sites

Well thanks for the input fellas! So far I only installed 2 fans. Picked up a rheostat from radio shack and it was 3 watts and I was pushing 9..soooo she was toasty. Anyway...I thought to myself..they are in fact "computer fans" You can by computer fan speed controllers for computers to run the fans. They are only 8 bucks. I'm going to try that. Thanks again!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Your Responses - Share & Have Fun :)

    • scary interesting...
    • Article on WSJ.com today about a European clean meat startup getting nearly $9 million in funding from Merck. With big pharma in the game, is there really any doubt it will be on store shelves soon? The cattle and pork industry better come up with a "pink slime" type of name for this, or they can kiss their herds goodbye. Franken Meat? https://www.wsj.com/articles/startup-producing-cell-grown-meat-raises-new-funding-1531738800?mod=hp_lista_pos4
    • sorry, quoted wrong post.   If one quotes a quote, the system messes up the attribution
    • Water that doesn't come out of a plastic bottle.
    • That's YOUR opinion.    Just remember, everything is fine, in moderation.
    • I do it, have experience with both homers and shooters. I am not a die hard as I was a few years ago but will get back into more when I get a new pup here in the near future.   The birds are not to bad to care for just need food and water. My experience and most troubles have been trying to keep critters out of the pigeon loft. Mink etc like to wreak havoc and it sucks when you lose all your birds to a stupid rodent. Especially the homers after you put in all the work to get them coming back. I haven't had any issues keeping birds at home by the dogs. Best part with the homers is if I train away from home, most times the birds are back home in the loft before I get back lol.   As for working the dog, you probably want to invest in a bird launcher as well especially since your dogs a pointer. Not sure how steady your dog will be or what kind of prey drive it will have. Hopefully you letting it chase birds already didnt cause any issues. I would just slowly introduce them to the pigeons. Might even start with just clipping some flight feathers and throw it in an open area and see how your dog reacts and go from there.   It should point naturally but just use the launcher to steady the dog up. Just look up methods with a check cord etc. when using the launcher. If you want them steady to flush or steady to shot that's up to you but that's way down the road yet. Some of that  pointing should come natural but with this dog being a little older you never know what your gonna get but never too late to start either I guess.    good luck
    • Maybe, We have some of that disease in the family. I'm of the opinion that if you are diabetic the kind of beer you should drink is NO BEER. 
    • Not if you're diabetic.
    • Anyone here have any experience with keeping and using pigeons, especially homers, for dog training?   I have an almost 2 year old Brittany that has not even been out hunting yet.... Last fall he was pretty young yet plus I had some health issues that kept me unable to walk around the woods or fields.   I'm not trying to turn my dog into some kind of world champion hunter or anything. I just want to be able to spend more time, all year long as opposed to only hunting season,  doing the thing he loves to do the most. We already have a great time on a daily basis playing an endless game of fetch and he is the most prolific tennis ball catcher (after one bounce) that I have ever seen. He also spends his days chasing rabbits, birds and squirrels in our fenced in yard along with lounging in his very own pool on hot days. He is trained to do all the normal things like sit, lay, shake, come, etc and I have no doubt that he has lots of natural hunting instinct so this seems to be where the progression of his training should head.   I do live in town but as long as I'm not keeping dozens of birds at one time, I don't think it will be an issue. I will check with the city before proceeding though. I'm thinking of getting about 6 homing pigeon squeakers and keeping them in a hutch in my yard. Is there any problem with the birds being in the same yard as the dog?   I'm thinking I could go out to the country on any given day and plant a few birds for my dog to sniff out. I have access to private property to do this on but I am wondering, is it legal to do this on wildlife management areas? I think I recall that after a certain date it is OK to train dogs?   Anyone else do this? Any advice?
    • Light Beer, pffffft! Kind of like the fat lady ordering 4 Big Macs, 3 orders of fries and a diet soda. 
×