PC Thermometer Using DS1621

The purpose of the project is to create a thermometer that can be plugged on any free serial port without using any programmable components such as microcontrollers.

The thermometer is cheap and gives an accurate temperature reading to 0.5°C with no calibration. Only the sensor IC is needed in the single-sensor version along with a voltage regulator, and a handful of diodes and resistors. The DS1621 temperature sensor is the main component of this circuit. It is a digital temperature sensor that measures the temperature transforming it in a digital value.

The DS1621 is capable to transmit ambient temperature through an inter-integrated circuit bus or I2C by just applying 5V stabilized power. This is a standard transmission scheme for connecting a multitude of ICs together using just two wires, the clock wire and the data wire.

During the construction of the SMT style of PC thermometer, the PCB was prepared by making it spotlessly clean in order to etch and solder well. Special preparation for soldering is needed for the LM2936Z5 voltage regulator. The PCB is designed to fit between the pins of the serial port connector which is the last part to solder.

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