Joe Buddy: A Beverage Temperature Regulator

The idea.

When the temperature drops in the winter, one common approach is to drink warm beverages to keep warm. Unfortunately, these beverages frequently cool down below a desired temperature before full consumption. The purpose of this device is to monitor the temperature of a hot beverage and turn on a heating element when the temperature drops below the user’s desired temperature. The user input is digitally displayed in ºC using a dual slope converter. A PID control system is used to `control the function of the heater. I worked with a partner to design this device. We worked together on the entirety of the project, but I took the lead on the Dual Slope ADC and he took the lead on the PID controller.

The Subsystems

The project was divided into two main subsystems: a dual slope ADC converter and a PID controller.

  • 1. Temperature Probe

    We used a TMP36 uses a change in temperature to produce a voltage drop that triggers a proportional analog signal.

  • 2. User Set Temperature

    Potentiometer that can be set to reflect a temperature from 50º to 100ºC that the user wants the beverage to stay at.

  • 3. Dual Slope ADC

    This circuit takes the input analog voltage signal from user set temperature and converts it into a seven segment display readout of that temperature. 5 subcomponents are used to create this component: 1. switch 2. integrator 3. comparator 4. counter/control 5. digital output

  • 4. PID controller

    Used to create a faster more accurate response from the heating element. A potentiometer in our inverting summing can be used to make fine-tune adjustments by hand for the characteristics of the system.

  • 5. Heating Element/Switch

    The simulated heating element is meant to represent a typical cup holder style mug warmer you would find for use in a 12V car outlet. We used a Darlington Pair setup to downsize the power draw.

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The complete schematic is shown in the images above. If you would like to learn more about the project, please check out the full document that is linked below.