Proving Oven – part 2

After last week’s exciting episode where i waffled on about some numbers and stuff, its now time to put some of the theory into practice. Firstly, the improving of the “oven” itself by adding some aluminium foil to improve its thermal retention properties (natch) and to try and stop it from smelling like melty plastic.

A quick test of this saw the light heating up the oven from 19 degrees to 30 degrees in approximately half the time it took before. And now to the switch. There are several ways of doing this and the first attempt is to use a kit form of thermostat control circuit. Theres a few around, either at electronics shops or even home brew shops (maybe even Off Ya Tree…). Basically this is a temperature resistor that acts as a switch. As we be using mains electricity (240 volts in this country, gringos) it needs a beefy relay to be able to safely handle switching the current on and off. This kit (KC5476 from Jaycar) requires a bit of soldering.

And some careful metering, as this little sucker has to use a 12v rail to switch 240v. Yes, i can hear the cooking fanatics groan in boredom…The finished circuit board takes a 12v in and has a temperature sensor on a lead so it can be placed where you like. Also, this is a switchable device that can operate to turn something on or off at a set temperature, so its suitable for cooling or heating. The point is its supposed to be efficient and cheap to run. So now its time for a soak test and calibration.

The testing proves that the circuit works and does what is intended, however it seems that this circuit is only rated for a limited temperature range with a maximum achievable of 19-20 degrees centigrade. So this will mean that part 3 will be tweaks and hackery to get the resistance value into the range we need to get the operating temperature to be within the median of 24-27C. Stay tuned….

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1 Response to “Proving Oven – part 2”


  1. 1 jo June 17, 2010 at 12:36 am

    omg though of course i can’t understand one word of this, i do believe that M is some kind of genius and that the two of you have combined your powers in the most delicious ways known to man.

    that and Miss Swan’s sciencey brain would literally explode if she saw this.

    kudos all!


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