Apply 8 bit microcomputer of microchip to the temperature detecting board. And the power supply is the AAA battery. The display is LCD(backlight) or 7 segments LED a. Apply 8 bit microcomputer of NEC or Toshiba to main controller b. Apply 8 bit microcomputer of microchip to the temperature detecting board. And the power supply is the AAA battery. c. The precision of temperature control