Reptile & Amphibian Forums

Hello, thought some of you might be interested in doing this also. Recently, I've noticed my corn snake's hot side is a bit too hot, but I didn't feel like handing over ~20 bucks at the local pet store for the voltage regulator.
As any electrical engineer would do, I went shopping at Menards and bought a light dimmer switch and an outlet and made my own for ~6 bucks! Check it out. I think I might make a another one to regulate the intensity of my ball python light. Anyway, here is one of the pictures.

ALTHOUGH VERY SIMPLE TO WIRE, MAKE SURE YOU ARE CONFIDENT IN YOUR WIRING SKILLS IF YOU PLAN ON MAKING ONE OF THESE!

With that said, if anyone would like further detail on how to save a bit of $$ espicially for those with large collections send me an email.
Jesse

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1.0 Corn Snake
1.0 Ball Python

n/p

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1.0 Corn Snake
1.0 Ball Python

that is great could you please send me the plans at senecabear@msn.com also could it be modified to acept more recepticals? almost like a power surge protector strip. thanks steve
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.3 ball pythons
3. felines(main coon,siamese,mix)
2. dogs botrh muts
1.1 kids karl20, jessica12
.1 georgeous wife

Radio Shack sells small 110 VAC lamps - you can mount one to the side of your outlet box and wire it in parallel with the load outlets. Then you'll have a visual indication of power level out to the load. Like you said though, do this only if you know how to wire AC circuits properly.

That's a good idea. I marked the min and max on the box after I took the pictures above. That showed me how much power was being delivered to the pad.(or so I thought) But as anyone whose used one of these light dimmers would know, they aren't linear, and there is a smaller window of adjustment than originally expected, but it does work well, and my cage is now at the desired temp.
jess
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1.0 Corn Snake
1.0 Ball Python

Is it that the dimmers are non-linear across their range or that the relationship between wattage and heat output is non-linear?

Actually, I should rephrase that. I'm sure the latter relationship is non-linear, so how much does that contribute to the non-linear output of heat sources ran through rheostats? I'm guessing near 0.

Also, some less expensive rheostats have a narrower range of restriction. I've wired rheostats between $5 and $12 and ran identical light bulbs off of them. They both allowed for max output, of course, but the cheaper product did not dim the bulb as much before turning off.

And no surprise, the more rhestats with the greatest range were had the greatest range of adjustment and were easier to "dial in" when used with Flexwatt.

I suspect this is also contributing to the narrow range you've seen. To be fair, I've not tested this in over 10 years. It may no longer be the case.

I would have to disagree with your statement previous. You said that it's a non-linear relationship between the wattage and the heat output. This would violate the first law of thermodynamics. That is energy conservation. If you input X amount of energy, then x amount of enegry must be released. For example, a 60 watt light bulb only converts about 5% of the energy to light, but the remaing 95% gets released as heat.
With a under tank heater, light energy isn't possible (at least I don't think it is) so if the heating element is indeed consuming 25watts for example, then it must be convering the 25 watts to either heat, light, motion etc.
(and I think we can rule out light and motion for the most part)
I think what you are experiencing comes from the potentiometer, or "light dimmer switch". These are non-linear, ie, if you turn the knob 30 degree you might get a 20% power increase. Another 30 degrees might give you 60% increase. While yet another 30 degree twist might give you 120% increase.
It's also true that the bigger the difference between the cage tempeture and the ambient air around the cage, the more heat lose will occur. I suppose all of this plays into what we experience.

On a side note, this devices, I orginally posted, is working great!
jesse Thanks again for all the replies
First Law of Thermodynamics

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1.0 Corn Snake
1.0 Ball Python

Interesting. Why is it then that ceramic heat emitters (that produce high proportions of infared wavelengths) show a non-linear relationship between wattage and heat?

The do not produce any motion nor any light so, in theory, a 100 watt heater should be twice as hot as a 50 watt heater, but they are not (even when measuring surface temps).

I'm grasping at straws here, but are there wavelengths of light not visible to humans that also do not generate any heat?

Duh!!... I forgot to think about the simplest explanation to this...

I'm sure these non-linear relationships are due to heat loss out of the system. Obviously when we measure the heat produced by non light emitting heat sources we are not accounting for all of the heat produced. It makes sense that with different wattage heaters there may be a disproportionate loss of heat.

So there would still be a non-linear relationship as I suggested in my original post, but only because we're not accounting for how heat escapes from a system.

Right, I agree. I think those non-linearities (sp?) are coming from your heat lose, not he production.
jesse
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1.0 Corn Snake
1.0 Ball Python

When making this contraption make sure the dimmer is rated for the total wattage of lights that you are powering. don't get me wrong I'm not knocking your Idea. I've done it myself. But if you only paid six bucks then you didn't buy a decent dimmer. so it's probably not rated for much.

When you build it take into account the total wattage. If you are powering two 75 watt bulbs then you have a total of 150 watts and so on . so your dimmer needs to be rated for at least 150 watts. If your dimmer is not rated for that much wattage don't use it . If its not sufficient then possible probs switch will go bad early, worst case scenario you could cause a fire and that 15-20 bucks you just saved just cost you thousands of dollars not to mention you beloved critter. So when building this don't be a tight 4$$. and if you don't have a common knowledge of electricity do not attempt it's just an accident waiting to happen

I am well aware of this ( masters degree in electrical engineering)that was the first thing I looked into. It's a 600 watt dimmer. I am only powering one 40 gallon zoo med tank heater which is a mere 16 watt heater unit. I challenge you to find any dimmer available for lighting use that is 120V and can only handle 16 Watts. Now some people are starting to use 12V lighting in their houses and using a dimmer switch for that application could lead to trouble.
Jesse
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1.0 Corn Snake
1.0 Ball Python

But I agree, if you start stringing a bunch of other heater units and lights on this, you always need to be aware of your load.
jess
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1.0 Corn Snake
1.0 Ball Python