Easiest way to keep water at a certain temperature?

[Eli]

So, I need to keep some water at ~72ºF. Aquatic life, and all that.

A regular fish tank heater with built in thermostat(over the tank lip kind) will not work by itself.

Wal-Mart sells these 6W(IIRC, might be 12) fishtank heaters meant for fish bowls, but they don't have a built in thermostat.

This is the only thing I could find that I might be able to work with.

3A is more than enough for the little heater.

I'm stuck on whether the LM35 temperature sensor can be remotely mounted.

I'm not sure if the additional capacitance added by the length of wires would mess it up. I'm also pretty sure that the sensor's leads can't be in the water, so I'm not really sure how I could seal it up and make a usable temperature probe. Epoxy I guess?

Maybe one of you have l33t3r google skills and can find something different. I've also found something similar, only 2A max on the load.

Any electronics engineer type people wanna build me a simple thermostat? I'd pay you, of course.

<--- thinking maybe I should take EE.. lol

 

[AFB]

Just pour some amonia in o the tank and be done with it .

 

[notfred]

Why wont a regular fish tank heater work?

 

[Eli]

Originally posted by: notfred
Why wont a regular fish tank heater work?

The water level is too far below the lip of the bucket.

 

[notfred]

Originally posted by: Eli

Originally posted by: notfred
Why wont a regular fish tank heater work?

The water level is too far below the lip of the bucket.

So make a little bracket that drops the heater part way into the bucket.

 

[bleeb]

Originally posted by: amdfanboy
Just pour some amonia in o the tank and be done with it .

 

[notfred]

Or buy one of these submersible heaters.

 

[Eli]

Originally posted by: notfred

Originally posted by: Eli

Originally posted by: notfred
Why wont a regular fish tank heater work?

The water level is too far below the lip of the bucket.

So make a little bracket that drops the heater part way into the bucket.

Hmm, might work. I'll have to work on this idea more.

Could be dangerous, though. It'd suck if the heater became submerged.

 

[Eli]

Originally posted by: notfred
Or buy one of these submersible heaters.

Hmm, this might also be workable, but those things are huge, and powerful.

It's a small bucket.

Only about a half a gallon of water. That's why the 6W heater would be adequate.

 

[notfred]

Originally posted by: Eli

Originally posted by: notfred
Or buy one of these submersible heaters.

Hmm, this might also be workable, but those things are huge, and powerful.

It's a small bucket.

Only about a half a gallon of water. That's why the 6W heater would be adequate.

Spending half an hour searching the internet or calling fish stores looking for a smaller submersible heater is probably easier than getting an EE degree and building your own.

 

[dighn]

hmm n/m

 

[Eli]

Originally posted by: notfred

Originally posted by: Eli

Originally posted by: notfred
Or buy one of these submersible heaters.

Hmm, this might also be workable, but those things are huge, and powerful.

It's a small bucket.

Only about a half a gallon of water. That's why the 6W heater would be adequate.

Spending half an hour searching the internet or calling fish stores looking for a smaller submersible heater is probably easier than getting an EE degree and building your own.

LMAO.. well, I didn't mean I'd get the EE degree just to build it.

I've always been interested in electronics. I know the basics, but it is frustrating to me that I can't just go build something so simple.

It would be like you being frustrated because you want to be able to write a simple software programs, know the basics, but don't really know how.. or something. heh.

 

[Eli]

Originally posted by: dighn
the lm35 outputs a voltage signal. i think it should be ok. how far are you talking about here?

It wouldn't have to be too far, maybe a foot, 2 at the most?

Maybe I could use a certain kind of wire or something... I dunno.

 

[dighn]

the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

 

[Eli]

Originally posted by: dighn
the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

Hmm.

How can I measure the capacitance of a wire? lol...

Perhaps it's not a big deal. I guess i'll just have to try it.

I was just hoping I could find one that was built using a regular thermisistor or something, though.

 

[dighn]

Originally posted by: Eli

Originally posted by: dighn
the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

Hmm.

How can I measure the capacitance of a wire? lol...

Perhaps it's not a big deal. I guess i'll just have to try it.

I was just hoping I could find one that was built using a regular thermisistor or something, though.

you'd need a capacitance meter. a shielded wire may go that high. not sure.

if it doesn' twork i suppose you could try hooking up an op amp as a buffer at the sensor end

 

[Eli]

Originally posted by: dighn

Originally posted by: Eli

Originally posted by: dighn
the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

Hmm.

How can I measure the capacitance of a wire? lol...

Perhaps it's not a big deal. I guess i'll just have to try it.

I was just hoping I could find one that was built using a regular thermisistor or something, though.

you'd need a capacitance meter. a shielded wire may go that high. not sure.

if it doesn' twork i suppose you could try hooking up an op amp as a buffer at the sensor end

Would I have to measure the capacitance of each length of wire for each lead and add them together?

 

[dighn]

Originally posted by: Eli

Originally posted by: dighn

Originally posted by: Eli

Originally posted by: dighn
the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

Hmm.

How can I measure the capacitance of a wire? lol...

Perhaps it's not a big deal. I guess i'll just have to try it.

I was just hoping I could find one that was built using a regular thermisistor or something, though.

you'd need a capacitance meter. a shielded wire may go that high. not sure.

if it doesn' twork i suppose you could try hooking up an op amp as a buffer at the sensor end

Would I have to measure the capacitance of each length of wire for each lead and add them together?

if you are using shielded wire it'd be between the center wire and the outer layer

unshielded umm between out and ground? not really sure about this

 

[Eli]

Originally posted by: dighn

Originally posted by: Eli

Originally posted by: dighn

Originally posted by: Eli

Originally posted by: dighn
the datasheet says it can only drive capacitance < 50 pf... i'm not sure what is the significance because temperature fluctations are not high in frequency...

Hmm.

How can I measure the capacitance of a wire? lol...

Perhaps it's not a big deal. I guess i'll just have to try it.

I was just hoping I could find one that was built using a regular thermisistor or something, though.

you'd need a capacitance meter. a shielded wire may go that high. not sure.

if it doesn' twork i suppose you could try hooking up an op amp as a buffer at the sensor end

Would I have to measure the capacitance of each length of wire for each lead and add them together?

if you are using shielded wire it'd be between the center wire and the outer layer

unshielded umm between out and ground? not really sure about this

Oh well.

I've been looking around for submersible heaters with a thermostat, and there is indeed a small 6" 25W one that will probably work.



Thanks everyone.