User manual

Therefore, we should not go any higher than 100 kΩ with the input

voltage divider to still get useful measuring results. For more

precise results, you may perform the calculation for a loaded

voltage divider and include the resistance of the ADC in R2.

Also consider that the tolerance adds up in a serial circuit.

If you are using two resistors with 5 % tolerance each for the

circuit shown, the total tolerance is already at 10 %.

The values of the E12-series have turned out to be ideal. They

are available in every electronic shop and are part of the

standard series. When building meters, however, the tolerances

of the components should be kept as low as possible for the most

precise measuring results.

Advice

The following link will take your to an online tool with which

you can calculate voltage divid-

ers: http://www.peacesoftware.de/

einigewerte/spannungsteiler.html

TEMPERATURE DISPLAY

IN DEGREES CELSIUS

AND FAHRENHEIT

This experiment shows how you can use a cost-efficient temperature

resistor like the NTC (Negative Temperature Coefficient Ther-

mistor) used here to program a simple LCD-thermometer.

An NTC is a resistor that changes its resistance depending on

its temperature. The NTC is called a hot conductor. This means

that its resistance reduces when the temperature increases.

The circuit diagram shows the setup in more detail. This is

another variable voltage divider, consisting of a 10-kΩ-fixed

resistor and the variable NTC-resistor. As the temperature

drops, the resistance of the NTC increases and so does the voltage

at the analogue input A0.

001 // Integrating LCD-Library

002 #include <LiquidCrystal.h>