# Measure 0-10V using Arduino

A thermocouple amplifier outputs a voltage range of 1.2V to 8.8V for the temperature range -260C till 1380C when using a K-type thermocouple.

The formula used to determinte the measured temperature is Ttc = ((Vout - 2.05) * 0.005)°C I am thinking of using two 1K ohm to divide the output voltage by 2 so as to fit within Arduino's max input voltage of 5V.] Question: For maximum accuracy when determining the temperature, is 1K ohm resistors suitable, or should we increase/decrease their resistance?

• What is the output impedance of the amplifier? – Ignacio Vazquez-Abrams Nov 8 '13 at 22:24
• I'm not able to find the output impedance from the datasheet, updated original post with link to product. – Nyxynyx Nov 8 '13 at 22:27
• 8.8V / 2 kOhms = 4.4 mA. Can your amplifier handle a 4.4 mA load? On the other end what maximum source impedance does the arduino need analog inputs to be driven with? It will be 500 Ohms with your proposed setup. – Olin Lathrop Nov 8 '13 at 22:45
• Page 10 of the amplifier used in the circuit shows the figure: "Output Voltage Swing vs. Load Resistance" and "Output Voltage Swing vs. Output Current" which shows that, for output resistances below 3k Ohms or currents above 1mA the output swing will start to reduce, and this will translate to a direct error to your measurement. – deadude Nov 9 '13 at 0:05