temp control circuit

Posted on Feb 5, 2014

For a few experiments such as solar air heaters, I needed a automatic turning on and off of a fan. Probably the simplest way to do this is with a bimetal snap disc thermal sensor. A bimetal snap disc thermal sensor is basically a switch that closes when a specific high temperature is reached and opens when a specific lower temperature is reached.

temp control circuit
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That way, by connecting in a fan in series with the switch, the fan would turn on when the high temperature is reached and off then the lower temperature is reached. They are also referred to as snap disk controllers and snap switches. In the UK they`re often referred to as thermostats or bimetalic thermostats and can be found at Sinolec Components - or RS Components - uk. rs-online. com. Make sure you get one where the temperature that turns on the fan (the switch closes) is higher than the temperature that turns off the fan (the switch opens. ) Most people use ones that turn on at 110F and off at 90F. WARNING: Many of the following photos and videos show Romex wire being used for the length of wire extending into the solar air heater to the snap disc sensor. These were used in experimental situations. Consider using teflon insulated wire instead. Why If it`s a sunny day and no air is being circulated through the heater because the house is already hot enough then the temperature where the wire is inside the solar air heater may get over 200F (93C). This may be over the wire`s insulation`s rating. If the insulation melts it may cause a short circuit and result in a fire. The following videos give step-by-step details for making the AC circuit. The first video introduces the snap disc sensor, tests a prototype circuit and shows how to determine the size of fuse needed for your fan or blower. It`s especially useful for...

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