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Ok don't just start bashing....

I have never used heat mats with rheostats. I use cables - mostly LONG ones, lol! Yes, sometimes it seems like there isn't a lot of space between too hot and too cold. But I don't consider it too hot unless it is melting the plastic, since the cable only goes across the short end of the box, and there is plenty of room to escape it.
 
That’s a good point Kathy. I think many people are sweating over trying to keep it precisely at 85* all the time when that really isn’t necessary. Somewhere in that neighborhood will work. The snake keeper doesn’t need to be more precise than Mother Nature.
 
LBoz said:
I have a sliding type dimmer, but even at its very lowest point, it allows my smallest heat mat to get too hot. Kathy and Betsy, what sizes do you find these work best on? Kathy, are you using these for a rack as well?
Click to expand...

Mine is on a 10g size ZooMed. Thermometer reads 84F +/- 1 degree & Icabod seems happy with it, so... I have cheap rheostats on 10G ZooMed UTHs for Humphrey & Attitude, and Attitude's temp is perfect & Humphrey's is sometimes a little high, so I think I am going back to HomeDespot for another sliding dimmer!
 
Hmmm....my issue could actually be the mat itself. I took it off one viv and put it on another. I don't use the self-stick anymore, as I probably damaged the wiring trying to get it off. Thanks, Betsy!
 
I always recommend using a piece of ceramic tile for the UTH's that have sticky sides. That way if you break the aquarium or want to move the UTH to another set-up you don't have to chance ruining the UTH when trying to get it unstuck. The ceramic is a nice heat sink as well.
I agree that precise temps aren't nearly as important as having a range of temps both on the high end and low. As long as the animals has the ability to choose where it wants to be I think mother nature will take care of the rest.
Terri
 
^I did end up doing that with a 10g I have now and it's worked well. I'll be moving him to a 20g this weekend. He's the cutest little butter I got from some cracker chick. ;)
 
I have had some schooling in the area of electronics, and temperature has an effect on resistance, as well as transistor bias. (this is why when your room temp changes you get varying temps). Ohm's law always applies, but the room temp will have an effect on the resistance and impedance of resistors and other electronics.

Also, I am not sure if any of these dimmers are strict "resistor" or old school rheostats, as those simply sunk power in a resistor. This would heat up the resistor, notice that these dimmers aren't acting like mini UTH's, if they were 100% resistors, they would get hot too. Now days, they use a transistor based means for controlling output, and that is much more energy efficient.

Your UTH is basically a nice big resistor, and thus, even your UTH will operate at different temps as your room temp changes, etc.

A thermostat is nice in that the temperature probe is a lot less likely to operate differently during temperature changes, that would make a poor temperature probe :)
So basically all a thermostat is doing is monitoring the temp and turning the UTH on and off when it gets to cold or hot.

Also, there are thermostats available for around $30 or $40, not all cost $100. I use the one for $35 from bigappleherp.com. Others use the "alife" one for $30. You may also want to check linens and things.com, sounds weird, but they are selling pet supplies cheap!

So anyway, just thought maybe this will help some people who want to know "why" these things occur.

It has been a while since I used my electronics schooling though, so if someone sees an error here I will gladly and humbly accept the correction :)
 
elipsis1 said:
I have had some schooling in the area of electronics, and temperature has an effect on resistance, as well as transistor bias. (this is why when your room temp changes you get varying temps). Ohm's law always applies, but the room temp will have an effect on the resistance and impedance of resistors and other electronics.

Also, I am not sure if any of these dimmers are strict "resistor" or old school rheostats, as those simply sunk power in a resistor. This would heat up the resistor, notice that these dimmers aren't acting like mini UTH's, if they were 100% resistors, they would get hot too. Now days, they use a transistor based means for controlling output, and that is much more energy efficient.

Your UTH is basically a nice big resistor, and thus, even your UTH will operate at different temps as your room temp changes, etc.

A thermostat is nice in that the temperature probe is a lot less likely to operate differently during temperature changes, that would make a poor temperature probe :)
So basically all a thermostat is doing is monitoring the temp and turning the UTH on and off when it gets to cold or hot.

Also, there are thermostats available for around $30 or $40, not all cost $100. I use the one for $35 from bigappleherp.com. Others use the "alife" one for $30. You may also want to check linens and things.com, sounds weird, but they are selling pet supplies cheap!

So anyway, just thought maybe this will help some people who want to know "why" these things occur.

It has been a while since I used my electronics schooling though, so if someone sees an error here I will gladly and humbly accept the correction :)
Click to expand...

When your room temperature varies 4 or 5 degrees the ampedance of a copper wire changes such a miniscule amount most VOR meters would not be able to read the change. Even with the new semi conductor type dimmer switches transistors are not used so bias would not come into play. They use a triode alternating current switch or triac to limit the current that is adjusted through the use of a potentiometer. The triac is similar to a diode and capacitor combination.

The problem with the $30 thermostats is that they are simply on off switches. Full power to no power. The reason the good thermostats cost more is that they are proportional thermostats. The will go from a few milliamps to 15 amps as is needed.
 
Couldn't remember the term triac... yep, Wade is correct... And I do agree, it would be a very small change in resistance/impedance.

It is probably the pot in the triac causing the wilder swings, cause that would change the base voltage?

Like I said, been a while... Thanks for the refresher Wade... :)
 
But do the cheap thermometers...

go on and off often enough that they can control the temps almost as well as the ones that let partial current through?

Sorry, my electrical knowledge is pretty much limited to turning on and off light switches, and plugging the cord in, lol! Lucky for me that hubby knows enough basic stuff to wire things together when needed.

Not THERMOMETERS - I meant THERMOSTATS, DUH!!!
 
Wade, never mind, I said "base voltage" which is me still thinking about transistors...

Hmm, now Wade has me wanting a proportional thermostat :)

I guess I need to add to my "how much $$ have you spent" thread now!
 
Yes Kathy, the cheaper ones will control the temperature just fine. Their real short fall is that the heating element is constantly heating up or cooling down and that shortens it's life. With the proportional thermostats like a Helix the heating element will stay about the same temperature all the time.

Sorry, I didn't mean to get so involved in this.
 
"...heating element is constantly heating up or cooling down and that shortens it's life..."

Makes PERFECT sense (and without any math, too, haha) - thanks!
 
I'm glad you did Wade...this has turned into a lot info for me...and I am surprisingly understanding it. Scott your info has been enlightening as well.

Thanks guys!
 
I'm noticing that very thing with one of my zoo meds. It took me the longest time to figure out what I was hearing...I thought my boa had an RI or something. It's the only one that goes on and off like that. Guess I better keep an eye on it.

Thanks for info, folks!
 
wade said:
Yes Kathy, the cheaper ones will control the temperature just fine. Their real short fall is that the heating element is constantly heating up or cooling down and that shortens it's life. With the proportional thermostats like a Helix the heating element will stay about the same temperature all the time.

Sorry, I didn't mean to get so involved in this.
Click to expand...

I have been advocating using a rheostat ($10) with a thermostat ($30) to achieve a more constant heat output and provide a level of redundancy.

This is not as good as the proportional thermostats, but a middle of the road compromise both with price and function.
 
oldsnow said:
has anyone had issues with a Home Depot dimmer being harder to stabilize?
Click to expand...

If the room temperature is constant, then those dimmers work perfectly. If the room temperature changes (even a little), then those do NOT work well at all. If you set it perfectly at a room temp of 75F, then it'll be WAY too hot at 80F room temp and WAY too cold at 70F room temp. A 5 degree room temp change can result in the heating element on the dimmer changing buy up to 15F (or more at the extremes). Dimmers ain't good in other words.

Once I discovered RANCOS, I NEVER used a dimmer again as a main temp controller! Now that Rancos are relatively cheap, I don't see a reason to use dimmers (personally, I mean) since they CAN be dangerous.
 
wade said:
Yes Kathy, the cheaper ones will control the temperature just fine. Their real short fall is that the heating element is constantly heating up or cooling down and that shortens it's life. With the proportional thermostats like a Helix the heating element will stay about the same temperature all the time.
Click to expand...

Huh, this hadn't occurred to me, but it makes sense. More motivation to replace my thermostats sooner. They control the temps just fine, but I don't want to kill all of my UTHs. Thanks!
 
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