Help - use of a thermistor in a drinks machine?

Question

Hi,
I need to hand in a 1st draft of my physics coursework tomorrow. I've made and tested a couple of circuits measuring the resistance of a thermistor at different temperatures. This is for the real-life situation of a drinks machine. The problem is I don't fully understand the purpose of a thermistor in a drinks machine. If it is to measure temperature why not just use a thermometer?
Any help would be greatly appreciated, apart from anything copied + pasted from wikipedia.

Answer 1

The point of the thermistor is that you can use it to electronically control other aspects of a circuit, say to turn on a refrigeration unit using a transistor switch once the temperature gets too high. It would be difficult to find out how to get a thermometer to do this--

Answer 2

You question has been answered that the thermistor is an electronic device and can be used to actually control the machine.

It would seem a little strange in a drinks machine though because I would expect a simple thermostat that cut off the water boiler at a set temperature. The same for the cooler. maybe this thing gives tea at a different temperature than coffee or something.

Thermistor are not often used anyway. A PT100 is more common place. Its resistance changes with temperature but it has a more standard relationship so many more "off the shelf" processing equipment accepts it.

Answer 3

You are absolutely right. Just use a thermometer. But you have to go and look at it and make a decision whether or not to turn up or down the cooling system to maintain a certain temperature.

Or, you can use a thermistor which will convert degrees into an electronic signal that can be sent to a logic circuit or microprocessor and have it control the cooling system for you.

A thermometer requires a person. A thermistor requires a power supply and some electronic intelligence. Your choice. Either one can do the job. If you have nothing more to do with your time, use a thermometer.

Answer 4

What is a thermistor? There are two types of thermistors. PTC and NTC ie. positive and negative temperature coefficient thermistors. That means the resistance increase with an increase in temperature (PTC) or decrease with an increase in temperature (NTC).

To use a thermistor you need to measure the voltage drop over it by passing a electrical current through it. Using a window comparator IC you can set up the switch on and switch off temperature and thereby regulate the temperature in the fridge.

A thermometer only provide a readout of the temperature by does not provide an output to regulate the temperature. provide.

Answer 5

Using a thermistor and other circuitry to control the drinking water temperature is way too luxery. Honestly, your drinking water machine would be very, very pricey.

There is a temperature probe located inside the water tank. The probe is made of bi-metal strip. The metals are either come in contact or open as the temperature changes. That is the easiest way to turn the cooling system on & off.