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Author Topic: Low Cost Thermostat  (Read 3396 times)

Offline BlueBee

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Low Cost Thermostat
« on: April 14, 2011, 12:08:18 am »
If you’re looking for a low cost thermostat for keeping bees warm or maybe even for an incubator, here’s a simple hardware only based solution that might work for you.

I just built and tested the following thermostat to control a heater in a bumble bee hive.  It looks like it works pretty good.  Why heat a BB house you’re probably asking…  I’m doing that so I can observe the BBs in a hive without having to fill the BB hive with any hair/cotton/fluff to keep them warm.  This will allow me to easily observe them thru a plexiglass cover.



I tested this thermostat in a BB hive in the basement.   The basement is pretty much a constant 65F.  I set this thermostat circuit to about 85F and stuck a commercial thermometer in there to see how good the system maintained temp.  I didn’t sit there and watch the thing all day, but it looked like as the hive lost a tad bit of heat, the thermostat would kick on at 84.6F.  Due to the large thermal mass of my heaters, the heat doesn’t start pouring out instantly so what I saw happening was the BB hive would keep dropping in temp until it hit 84.1F.  At that point the heat from the heaters would build up enough to start pushing the hive temps back up.  When the temps pushed back thru 84.6F, the thermostat would turn off the heater.  However due to heat stored into the cement heater, the hive temp would keep rising and overshoot to 85.5F before the cycle would repeat over and over.  So with my setup the best I can control is about +/- 1F.  That is certainly good enough for some bumble bees or keeping nucs warm. 

My guess is if I reduced the thermal mass of my bee heater I could get a tighter control system using this hardware only approach.  For tighter control, a micro controller would likely work best.  With a micro you could drive the heater with a PWM signal and tune the heat output from the heater to exactly match the heat loss from hive. 

To see photos of this hardware based thermostat, see my photobucket album here:
http://s1082.photobucket.com/albums/j365/MichiganBee/Thermostat/

Offline ScituateMA

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Re: Low Cost Thermostat
« Reply #1 on: February 23, 2014, 03:37:52 pm »
Hi I cant see any pictures here. I would like to learnt how to make a low cost termostat for my bee hives. Can you pls give more detailed info for someone with basic electrical knowledge?

Offline capt44

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Re: Low Cost Thermostat
« Reply #2 on: February 25, 2014, 04:04:36 pm »
I just bought a heater/fan with digital thermostat from   Incubator warehouse.com
They have several different models of thermostats
Richard Vardaman (capt44)

Offline BlueBee

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Re: Low Cost Thermostat
« Reply #3 on: February 27, 2014, 01:52:15 am »


Original photo link was broken when I reorganized my library about a year ago.  

This was a simple op amp based control.  Less than 2 dollars in parts.  A micro based solution is more flexible if you have basic microcontroller skills.  

If using a computer power supply for the DC source, remember it is a switcher and may need a minimum load to maintain regulation.

 

anything