The temperature recorder project uses a microcontroller PIC12F683 as main processor, a 32kBytes Serial EEPROM which can store up to 32,000 measurements and a thermistor as temperature sensor. The temperature is measured and stored at user programmable intervals with range from 1 second to 256 seconds. The time interval is set by programming it and the start time into the EEPROM.
Andrew M. Bishop, the designer said most of the time the PIC will be asleep and the EEPROM IC is inactive. This gives a very low current consumption of approximately 50 uA or about 1 mAh per day. The circuit diagram is very simple with only the ADC interface (one resistor), I2C interface (2 resistors), EEPROM IC, ICSP (socket, 1 diode and 1 resistor), oscillator (crystal and 2 capacitors).
Project Documentation and Schematic