So i want a simple device to monitor the temperature of my coffee and as the temperature belows my set value ,it reminds me: hey, your coffee is OK, you can drink it now!
As a graduate student studying history, I am not good at electronic, i can not understand anything about hardware programming such as Arduino too, but i believe, it is simple, and interesting!
I found some modules, plans to use a simple way to make such a device. The pictures above shows my thoughts of the solution.
This system uses wireless charging module, so the cup modifications do not affect its normal usage . After preparing your coffee, just place the cup on the special mat , as the coffee temperature became suitable for drinking, the buzzer will automatically reminds you drinking.
I use the following modules:
1. Temperature Threshold-Setting Module;
2. Wireless Charger;
3. 5~12V DC power, it is very common used, i believe there will be one in your home;
4. Buzzer & DC Jack;
5. Thermal Glue that you can get from any local convenience store;
6. Cup and Plastic Blocks;
Ok, with some tools such as knife and scissor, Let’s begin~
Step 1: Wireless Receiver+ Temperature Monitor
Althougth the circuit maybe easy for electronic students , it takes me 2 hours to understand. As the thermistor is NTC, so as the temperature higher than the set value set by the potentiometer, the LED will be ON, and will be OFF as the temperature lower than the set value.
But it is not want i intended. I need a buzzer shouting when the temperature is LOW and keep Silent when temperature is HIGH. So , i make some modifications:
1. Solder off the LED
2. Add a buzzer between the output and Ground.
As schematic_2 above.
And, in order to meet the current requirements of the buzzer, i modified the resistor between VCC and the output of the LM293 from 10K to 120 ohm.
Then, Connect the wireless receiver to the power circuit of the board. Connect the Red wire to VCC and Black wire to GND.
Step 2: Wireless Charger Connection
Step 3: Install the Wireless Receiver+ Temperature Monitor Onto the Cup
If you uses a cup that has a High-quality insulation , then I suggest that you use the new temperature sensor and put it to the inside of your cup so that it better monitor the coffer temperature, wish that the sensor does not change your coffee taste.
Finally, use a tape to fix the whole board to the glass wall. Note that do not cover the potentiometer, because we will need to adjust this potentiometer to set the “Reminding temperature” later.
Step 4: Prepare a Shell for the Wireless Charger
Also use a scissor to make a “pocket” in the plastic block , and put the wireless charger into it. Use a tape to to fix it.
Step 5: Adjust T the On-board Potentiometer to Set the “reminding Temperature”.
Pour some water that you think its temperature is ok for your drinking into the cup, and adjust the potentiometer to the threshold to make the buzzer just begin to shout/silent . So its further working, when the sensor detects the temperature of the liquid in the cup is higher than the set value , buzzer not ring; When the temperature starts below the set value, the buzzer will begin to
Reminds you the coffer is OK~
If you think the buzzer too loud and affect you and your colleague, you can change the position of the cover on the buzzer to adjust the loudness.