Heating 30celcius

Hello!
I need to make a heater for my pets (ants!!!)
A heater will be placed on one side of their ytong nest.
And need to have around 25/30 celcius.

My question is what Heating element would you suggest i used?

I have made a test one with a 5w10ohm ceramic resistor
A lm35 And a BD679 transistror.

Basic idea of the code is it checks the tepmerature on the lm35 and if the temo is lower it increases the pwm if its over the set temo it decreases the pwm.
So in a general idea i am happy with my code.

The resistor has a small surfise area
I Have seen on ebay aluminium PTC 5V 50C heaters,
Can i reduce/controll the heat with pwm?

How much heating power You need depends on the loss of temperature out to the surroundings. Does this pet house reside in room temperature or in the Artics? Isolation can help.

The pet is ants !
In general idea they need a gradient of heat (i will heat one side of the nest). The hottest part needs to be around 25/30 celcius. A heater around 5x8 cm should do the job. The heater will be encloed in the nest wall. If not enough heat goes through i can always increase the heating.

The whole nest will be enclosed in plexiglass

Design your heater to heat a copper or aluminum plate so as to spread the heat over a larger area and to smooth out the abrupt changes in temperature.

Paul

The big question is… So you get enough heat?

Heat is related to power (Watts) and power is calculated as Voltage X Current. It can also be calculated as V2/R or I2 X R. Assuming 5V and ignoring the voltage drop across the transistor you have 2.5W.

That’s the total heat energy. The actual temperature depends on the size and insulation of the enclosure and the ambient temperature.

PWM is rarely used for heating & cooling. The temperature can’t change instantly so normally the heat is turned-on whenever you are below-target and then turned off when you are above the target.

You could use PWM as a crude heat adjustment if there was no temperature sensor.

The resistor has a small surfise area

That doesn’t affect total heat/energy or the temperature inside the enclosure. A heatsink or larger resistor will “spread-out” the heat so the resistor itself will run cooler. And the enclosure may heat-up faster with more surface area.

Why not use an Ant Farm Heating mat?

Of course many an argument can be made for a heating lamp instead of a mat. The mat heats from the ground up and a heating lamp is from the top down, more natural for the ants.

A temperature controlled heating lamp placed to one side of the farm will give the gradient you are looking for.

A sensor placed in the ant farms dirt at the location of desired temperature can be used to control the heat lamp on off time with either a AC relay or controlling the phase angle firing of the AC power to the heat lamp. I like the phase angle fire over the relay method, the relay is sure to have a shortened mechanical life over electronics.


An Uno would be great for this job.

Link to the basic idea for controlling the phase angle fire

Internet search words I used "arduino ac dimmer". The diode temp probe will be substituted for the potentiometer.

A tough temperature probe can be made from a diode, search words "diode as temperature sensor". The diode soldered to one end of a coaxial cable, coat the probe and part of the cable with epoxy, animal safe. Once the probe is coated and the coating has dried, time to calibrate. Hook up the probe and circuit to the A:D. place probe, on a cable, into a mix of ice and salt water, printout the A:D readings on the serial monitor and now you know the probe value for 32F/0C. Place probe in boiling water, get reading, now you know value for 212F/100C. Math gets you the 25/30C

I have not found ants nest heat mat!
The reptile cables are not regulated and they give out more heat than i need.

The and farm is split in two areas nest/out world connected with tubes. The nest area i need to heat needs to be dark.

So i will try attaching a big heat sink on the resistor.

I will also do/try/search arduino as a dimmer :slight_smile:

Thanks alot :slight_smile:

Thin film "heaters" show up on the surplus market pretty regularly, and various random sizes.
G23514 - is a current example.
They're available from Digikey as well, but I think their primary use is in avionics, so they tend to be very pricey when NOT "surplus."

I'd stick with the high-wattage resistors, and some kind of heat-spreader, probably.