Temperature sensor to measure surface temperature compatible with Raspberry Pi

Question

Hello All,

I am looking for a temperature sensor that I can use to monitor the temperature of a surface with a raspberry pi. With no A/D on board the choices seem limited added to this is the need to find something that I can connect to a surface easily is not helping. Any ideas or suggestions would be greatly appreciated.

I was thinking of using a thermopile facing the surface but I cant seem to finf one that as a simple to use output (unclear data sheets aren't helping)

Thanks

Kas

shabaz · Answer

Hi Kas,

bwelsby and I did some fairly extensive (at the time) tests on the Pi 3, we used a thermistor and also examined the in-built measurement.

The information is dotted in multiple posts and comments though:

See here Raspberry Pi 3 Dynamic Current Consumption, Power and Temperature Tests

and Raspberry Pi temperature and cooling testing Part 1 initial tests.

Raspberry Pi 3 temperature and cooling testing Part 2 with a HAT tests.

Raspberry Pi 3 Cooling / Heat Sink Ideas

As you say, there is no ADC so that makes it a bit awkward. An option is to attach one (SPI or I2C for example) or use a multimeter and pen/paper, if you're capturing data over slower periods. The thermistor was a bead, so I drilled a hole for it (in heatsink).

An alternative could be an RTD device (e.g. PT100), they are also tiny and some have a flat surface, so you could tape it onto the chip.

You could use a larger semiconductor device (e.g. TO-92 package) but they have a slow thermal response.

shabaz · Answer

Just re-reading, I may have misunderstood your requirement. If you're measuring the temperature of a different surface (i.e. not the Pi) then similar comments may apply, or you may need a different method (e.g. thermocouple) depending on the expected temperature of the target surface. One example method is here, connected to the Pi: Temperature Measurement for Lab and Science Projects

shabaz · Answer

Hi Kas, For low thermal mass perhaps a very small SMD sized silicon sensor, or a thermocouple or thermistor or RTD as you say with small size. If you want to use on of the latter devices, then you'll need an ADC, and you could use the same ADC as in the project mentioned earlier, since they are available on a PCB at low cost from ebay, it is the ADS1118. Here is an example one: ADS1118 16-bit AD Converter ADC SPI Communication Module Development Board | eBay RTDs are available as small flat devices, so could be taped onto a wall for example. Another approach could be non-contact IR thermal sensing.

beacon_dave · Answer

How about a DS18B20 one wire type digital sensor ? Product Link Product Link https://www.element14.com/community/community/stem-academy/blog/2014/12/13/raspberry-pi--ds18b20-temperature-sensor

dougw · Answer

There are many I2C sensors that could be used: TMP102 MCP9808 Si705x or spi sensors LM74 MAX6662 DS1722 TC77 etc

Temperature sensor to measure surface temperature compatible with Raspberry Pi

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