Help - project for a electrical newbie. - Fan , Switch, Battery 3

[TomsSound]

Hello,
This is a little project that I'm working on and would like some input from experts
Here is a diagram of what I'm trying to do.

http://3volution.org/project/Diagram1.gif

Basically, I want to hook up a small computer fan to a button/toggle switch and a 9volt battery.
I know it works. I have tested it out and seems to do what I want, But I wanted to know if It could be done better or if I'm missing anything important. Is it normal for the battery to heat up so much.
I don't know much about this stuff so go easy on me. Thanks

 

[VEBill]

Is the battery heating up more when the fan is off ?

The reason I ask is that there appears to be an extra wire connected to the switch. It might be shorting out the battery when the button is not On.

Need more info to be sure (switch pin-out).

 

[jraef]

Generally, The black wire would not need to go back to the switch. Yellow wire would be + of the battery to the switch. Red goes out of the switch to + of the fan. Black goes - of the fan to - of the battery. You need the circuit to be a loop (hence the word "circuit") from + to -, through the switch (which breaks the loop) and through the winding of the motor, which does the work.

The only reason to run the - to the switch would be if there was a lamp on it, but IMHO you will not want to waste the limited battery capacity you have on a lamp.

The battery may also heat up because they are rated for Amp output, not just voltage. If you are using a small 9V battery such as found in a multimeter or smake detector, they are not designed to put out a lot of current for very long.

"Venditori de oleum-vipera non vigere excordis populi"

 

[TomsSound]

Thanks guys...
Yes the switch has 2 led lights on it.
one for on ... one for off.
I'm actually trying to make this fit in a Paintball mask to combat fogging of my glasses.

I got it all together last night .. works pretty good. Except the heating issue. But I would only run it for short periods of time to de-fog the mask.

Anyone have any ideas of how to make it better?
Would resistors/capacitors or any other items make this work better?

 

[TomsSound]

updated the pic to show the LED Lights

not sure about the amp ratings on the fan.
I don't think its really heating up till the fan is on.
I'll try to post pics of what I've made tonight.

 

[TomsSound]

was actually thinking of replacing the fan i'm using now... with one of these..

https://www.arcade-electronics.com/..._catid=741&sid=7@mDZ21Em2e@99T-20105153104.42

 

[itsmoked]

TomsSound,
Don't bother... The two fans you show are both WAYYYYY to large a load for a 9V battery. You should not ask a 9V battery for more than about 10mA. The low current fan of the two you show in that link draws 70mA!! This will heat the battery up and kill it in minutes....
Something that would work A LOT better would be a battery pack holder like this item in Digikey. They also come with just solder lugs and with snaps just like the top of a nine volt battery.

http://rocky.digikey.com/WebLib/Memory Protection Devices/Web Photos/BH26AAW.jpg

 

[TomsSound]

itssmoked... so you think say.. 6 or 8 AA batteries would be better... cooler(temp)? last longer?
I guess I could run a wire from a pocket up to the mask.

 

[TomsSound]

about how much mA could the 6 or 8 AA batteries handle?
Thanks !!

 

[VEBill]

"...not ask a 9V battery for more than about 10mA."

That sounded a bit low to me so I checked. The Duracell datasheets for 9V alkalines (Ultra and CopperTop) show that the life should be several hours (five-ish) at 70mA current draw. Although they don't clearly provide a numerical limit, the life curves imply that the upper current rating is much, much higher than 10mA.

A 6-cell AA-cell pack would be much better and cheaper to boot.

 

[VEBill]

Link:

http://www.duracell.com/oem/ProductData/

 

[itsmoked]

VE1BLL That's the site I came from... If you look closer you will see that the larger drain rates come with voltages like 4.8V at the terminals.. And that's all based on 21C. If the battery is allowed to heat up the results will substantially worse.


Toms Yes! 6 AA would serve you a heck of a lot better. They would provide you with about 10Hrs of life if you use the .07Amp fan in your list. You can also tape the pack to your helmet, that wouldn't be too heavy.

 

[jraef]

...or get a car battery and a little hand cart to drag around behind you. Might make you an easier target, but you could run a small dehumidifier or AC unit for your goggles. So when your opponents are running around faster but become blinded by foggy goggles, you could be sitting in one spot with clear vision and pick them off!

"Venditori de oleum-vipera non vigere excordis populi"

 

[afterhrs]

Or you could get a back pack, a smaller 12v battery(lawnmower), and purshase some defrosting strips that are used in the rear windows of vehicles. I bet a clever guy
like you could even arrange the defrosting strips in some sort of crosshair pattern to improve your marksmanship.

Regards,
Afterhrs

 

[afterhrs]

Is that marksmanship or paintsmanship.....

Regards,
afterhrs

 

[ko99]

Toms,

There are fans that only require 0.20W (40mA at 5V) instead of the 0.84W fan you proposed. Three AA batteries, even AAA, might last long enough for you. A few links:

http://www.sunonusa.com/pdf/2004dcfan2.pdf

http://www.nidec.com/ta100dc/ta100dc.htm

http://www.delta.com.tw/product/cp/dcfans/download/pdf/AFB/AFBseries.pdf

ko (

http://www.ecooling.biz)

 

[TomsSound]

lol.. thanks guys.. i appreciated the laugh.
Thinking a backpack and a deep-cycle marine battery might work best for me

 

[IRstuff]

You could probably run it directly off a computer laptop battery. They're usually good for several amp-hrs, compact, no chemical leakage potential, etc.

TTFN

 

[jraef]

Great idea from IRStuff. Many small laptops have small fans as well, I know my old TI laptop did. For what old laptops sell for it would probably cost less than a marine battery!

"Venditori de oleum-vipera non vigere excordis populi"

 

[Myndex]

You *can* operate 9V alkaline batteries up around 100ma or more, though the discharge curve gets a bit steep. These batteries do heat up more than other types (due to their construction as I recall - i.e. larger number of cells with less exterior surface area per cell for cooling).

In this application, I'd suggest using AAAs in a readily available battery holder. 9V bats are really for low current applications. AAAs you can run at up to an AMP (1000ma) though best discharge curves are under 250ma.



Andy

Andy Somers
Myndex Technologies Inc.