"Thermo" Project

This digital thermometer is one of the most popular projects I have ever done. I have heard from quite a few people who have built it and some that have even used it as a basis as a thermostat for their barns and for monitoring incubator temperatures for hatching chicks. These applications would seem to require better accuracy than I would have throught the circuit is capable of, but I have not been served with any papers yet.

The thermistor used for this application can be found very easily in "Radio Shack", but this is an issue for people who live outside of North America. In the Bill of Materials, I have noted the parameters of the thermistor so that you can find one of your own for use in this application.

Click Here to look at the application's source code.

The circuit used for this application is:

The bill of materials for this application is:

Part Description

U1 PIC12F84-04/P

U2 78L05

Y1 4 MHz Ceramic Resonator or Parallel Cut Crystal

R1, R12, R13 10K, 1/4 Watt Resistors

Q1, Q2, Q3 2N7000 N-Channel MOSFET Transistors in TO-92 Package

R2 - R9 220W, 1/4 Watt Resistors

R10 100W, 1/4 Watt Resistor

R10 10K, -3.85% NTC Thermistor ("Radio Shack" part number 281-110)

C1 10 uF, 35 Volt Electrolytic Capacitor

C2, C5 0.1 uF, 16 Volt Tantalum Capacitor

C3, C4 27 - 33 pF, Capacitors

J1 9 Volt Battery Clip

SW1, SW2 2x1 Male IDC Connector

Miscellaneous Breadboard Prototyping System, Wiring