Vivarium Circulation 101?

[Green Ghost]

I understand the issues that people are having with fan placement inside the tank. I've had issues with this kind of thing also.

Where can you place the fan so that it doesn't hurt the animal if it jumps on the fan? Right? (Because the frog may get it's feet chopped off by the impeller)

To solve this problem the fan could be covered with mosquito netting. First purchase the impeller guard for the fan and bolt it to the fan, then put mosquito netting on top. Silicone could hold it. So there's no way the frog can get his feet caught inside...

Now you can choose a location without worrying about killing any frogs.

2nd problem, power. Old AT power supplies (P/s) will work great. I'd get an a/c adapter if available. Check the voltage and amp rating on the fan as bareass mentioned get an adapter with the same voltage rating but a slightly higher ampere rating. So if your typical 80mm fan is rated at 12v / .8a then you would try for an adapter rated at 12v / 1a.

***EDIT : I forgot to meniton that old PC (AT) P/s's are great because they are switching P/s's and can supply the correct amount of current depending on the the load. That means if you put one fan on then the current is adjusted for that fan. If you add another fan later it will adjust in consequence. So that's practical and easy to use. The newer P/s's (ATX) can be used also but the PC board connector needs to be jumpered to be able to power on the P/s if it's not connected to a PC motherboard. That's why the older AT P/s's are better (and much cheaper) to use.

3rd problem how to regulate the fan. It's possible to regulate the fan speed and to have it come on and off. On and off is a timer. Simple. To regulate the airflow you need a potentiometer with the correct resistance to vary the voltage (and therefore change the impeller speed)

I'll try to get a wiring diagram up on here tomorrow night if I'm not too busy. Once you have the diagram you'll be able to do it. It's very easy.

Then the only thing that would be needed would be a digital humidity guage at the other end of the tank to determine how humid the tank is. After that it's just a question of trial and error trying to get the airflow and time that the fan stays on adjusted so that the correct level of humidity is maintained.

edit: I just found something here: Antec makes a 3 speed fan with the switch already built in - that might be easier than soldering a pot on. I think it's 15 bucks - even has LED's. Most computer stores would sell that.

Antec

Antec.com - TriCool Fan installation



So does that help?

[alex1976]

So with an AC adapter you want to have a slightly higher amp rating than the fan requires? I just want to make sure before I go wiring stuff up and burn out fans and/or adapters.
I guess the fan won't pull more than it needs?
Could you put that wiring diagram up anyway? It's great knowledge to have and I'm sure I'm not the only one who likes to have as many options as possible.

Thanks for all your help!

[Waterkeeper]

I would also like to see some wiring diagrams.. mostly how to wire in series, parallel, etc... I have my power supply and fans ready to go, but I know there are different ways to supply the same power to them.. I want to know the differences in power if they are wired in series, parallel, series/parallel or if you can even do this with fans...??

You can also regulate the flow of a fan by limiting the air space behind the blades. they are only as efficient as the air behind them. for example.. take a pc fan running on the table blowing in your face. place a piece of cardboard behind it, and start to move it towad the fan, as you get closer with the cardboard the air flow will drop.

maximum airflow from a fan requires the space behind the fan to be almost equal to the radius of the blades. so if a 4" fan is 1" from the wall you will only be pushing roughly 25% of the fans potential.

[bareass]

the reason you want a higher amperage then you need is so the power isn't being pumped at full tilt. the fan can only use the amperage it's rated at. its like driving a car 100mph. you wouldn't want the engine to top out at 100mph or it will blow very quickly.
for the series and parallel question. if you have more then one fan you will want them wired in parallel. in parallel, each load will receive the same voltage. in series the first fan will drop the voltage going to the next.
make sure you use two of the same or similar fans when doing this.. and note that the required amps is now increase. add the amps together and that what you need to supply. to wire it up. connect like wires together. for example. red to red black to black.

[bareass]

now my issue is more of where to put it. as well as what's the difference. i mean i'm pushing air in from out... but its still moving and changing the air thats inside the tank. and if i were to put it in the tank where should i put it? i would love to see some pics of how people hid their fans

[Waterkeeper]

Which fan is considered the "first" when wired in series?

[bareass]

the first fan after the adapter or power supply from positive to negative. but it would be best to use parallel wiring.

[bareass]

here an example of the 2 types of wiring
hope this helps.. replace the battery with your adapter

[Green Ghost]

Ok I finially finished. Shame on me I forgot how to use Visio. Anyways I tried to give a few examples of what to expect when wiring up fans to a 12V source (the a/c adapter)



The wavy lines are resistances which would be your fan(s) in the circuit.

So you can see how the current is affected in each type of circuit.

If this doesn't answer what you wanted just ask me.

[Waterkeeper]

BINGO! on the nose green.. Thank You sooooo much.

For those of you worried about playing with electricity and fires and such....

(KIDS DON"T TRY THIS AT HOME!!)

I got ballsy today and decided to see what was up with the amount of power we are dealing with.

My fans are 40mm(super small) laptop fans. 12Volt .13 amp. measure about 1.5 inch across.
my power supply is adjustable but i set it to 12Volt and .15 amp

I plugged in the PS and touched the wires together and got nothing. I touched both the wires with my same finger and felt nothing... and I touched the positive to my left nipple and the negative to my right.. and got nothing..

.15Amp is NOTHING TO WORRY ABOUT!

over time loose connections might cause some heat and a hazard, but from what my Nips tell me, this amperage isn't much to worry about. bigger fans and higher amperage power supplies will be a different story however. but in my experience you don't really learn anything about electricity till you temporarily blind yourself with a fireball spark or two..