In this post we will build a circuit that can be used for identifying and alerting the user regarding the right temperature of the coffee. The LED indicators will indicator if the coffee is too hot to drink, or may be getting too cold to continue drinking.
The ideal temperature for coffee is at minimum 80 degrees Celsius. Which may be the temperature where our tongue is just able to taste the coffee. however let's not get into that in this article.
Simply because coffee is treated as a popular recommendation for the nourriture referred to as 'Monday - morning', we made the decision that it might be significantly better to get rid of all history of complexities from this question of 'how sizzling is it?'
As the coffee or tea temperature indicator circuit schematic above indicates, there isn't a great deal of associated with this circuit. A voltage regulator, a temperature to voltage converter, a op amp, a handful of transistors and LED, and a few resistors and capacitors, could be the overall part number.
The procedure is usually simple. In case the coffee reaches under the best temperature the output of IC3 will be low, holding T1 turned off. The other transistor, T2, as a result will conduct andthe red LED illuminates showing that the coffee is actually cold.
When the temperature is sufficiently high (over IOC), the green LED turns ON. What really takes place is this: The temperature, that is analyzed by IC2, is transformed into a voltage.
The coffee temperature display circuit concept is that the LM35 must remain suspended in the coffee, hence the three terminals of the IC ought to stay isolated.
This could be achieved by installing the LM35 IC within an old ballpoint pen, or by sealing it with some sort of non toxic glue. or inside certain heat absorbing tube.
The output voltage of IC2 will rise by around 10 mV for each single degree Celsius rise in temperature. The reference voltage at the inverting input of IC3 has to be fixed at 800 mV using P1.
When the voltage on the non-inverting input of the op amp also gets to 800 mV, the output of the comparator changes to high logic. This result in T1 to conduct, turning ON T2 and switching OFF red LED.
The green LED at this point illuminates indicating that the coffee is about the correct temperature to drink.
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