If you are looking for a cheap and accurate temperature sensor, use the LM35 silicon temperature sensor. It’s good for general temperature sensing like ambient temperature monitoring, incubator temperature sensing, overheat protection and even on fire alarms. The LM35 is a voltage output temperature sensor which has a response of 10 millivolts per degree centigrade and it is accurate within 0.5 degree centigrade. It can operate at -55 C to +150 C and it accepts supply voltages from 4 volts up to 30 volts. The current cost of the LM35 in Philippines is about 100 pesos. Ease of use and simple circuitry is a good feature of the LM35 since all you need to do is power up the unit and just connect the output pin to a digital tester or a microcontroller and you have an instant digital thermometer.