How to measure temperature?


The LM35 is a general purpose temperature sensor which can be used to measure temperature from -30..100C.

It can directly be soldered to the connectors of the USB-DUX or USB-DUX sigma boards. To seal it just use some heatshrink and/or epoxy.

USB-DUX sigma

The USB-DUX sigma board uses a standard 44 pin HD connector. The input range of the USB-DUX sigma board (+/-1.35V) matches perfectly the output voltage range of the LM35.

GND is available on many pins on the HD connector (check out the pinout) so that you can choose the ones which are easiest to solder to. R5 should be soldered close to the D connector (e.g. inside of the backshell) which acts as a termination and prevents oscillations. To be able to measure negative temperatures connect a 100K resistor between pins 16 and 31 (-5V).

ComponentFarnell/onecall order code
44pin HD connector for the USB-DUX sigma1071810
Backshell for the connector470107


The USBDUX-D board uses a standard 25 pin D connector.

Circuit diagram

R1 is needed for a longer cable (>10cm) between the USB-DUX D and the LM35.

ComponentFarnell/onecall order code
25pin D connector for the USB-DUX D1084674
Backshell for the connector470107