It is to keep the Coffee warm and also to make the coffee while travelling... It is powered by IDT wireless charger
Schematic file, Gerber File
Zip Archive - 55.60 kB - 05/10/2016 at 17:11
I uploaded video in Youtube and ashared its link in project
Connect 5.2 ohm resistor to 5 volt power supply.
so that I=V\R, I = 5/5.2 =0.961 amps
Total power = V*I = 5*0.961 = 4.8 watts (u will get 45 C)
After connecting 5.2 ohm to 5 volt supply u can feel warm around the resistor. USE 2 watts Resistor... I used 1/2 watts and burnt it.
If you want to produce more heat then use 2 amp power bank and change the resistor to 2.7 Ohms (power = 10watts).
For uniform heating of coffee cup, I used two resistor on each sides.
So connect two 10 ohm Resistors in parallel to make 5 ohm like shown in the image.
Attach the Resistor to the Coffee Cup and apply Thermal Paste.
Open the Power bank carefully you will find battery and DC-DC converter. You can also use the powerbank directly without opening it, but I did this to reduce the size.
Now test the Coffee cup by connecting two ends of the Resistor wires to Powerbank output through USB cable. You can feel the increase in temperature and connect IDT wireless Receiver to the Powerbank input. Now the battery can be charged using Wireless receiver. Now add a transistor switch (TIP 29) in between the powerbank output and resistors I.e cut the usb cable +vcc wire and attach collector of transistor to one end and emitter to other end of the cable so that the heater can be controlled by transistor base voltage.
Prepare the case for coffee cup, I used a Flask and attach the wireless receiver to the bottom of the case.
Stick the wireless Receiver to the bottom of the case and Connect powerbank to it.