# Artifacts in Temperature and Relative Humidity readings when powered via USB/5V **URL:** \ **Category:** Airnote\ **Created:** [May 12, 2022, 12:50pm UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824 "2022-05-12T12:50:46Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![AlberTO](https://avatars.discourse-cdn.com/v4/letter/a/ea5d25/32.png) [@AlberTO](https://discuss.blues.com/u/AlberTO)\ **Post date:** [May 12, 2022, 12:50pm UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/1 "2022-05-12T12:50:46Z")
There is a problem when my device is powered via an external 5 V USB source: a lot of pulse-like artifacts appear in the temperature measurements and therefore also in the relative humidity readings, making these traces unusable. An example is shown in the attached screenshot ![02_Artifacts after external 5 V connection_Annot](https://us1.discourse-cdn.com/flex020/uploads/blues/original/1X/6561589a93953b9110c7ad06bec4305aee0abb7c.png) The issue appeared after approx. 2 hours from the connection of the external supply. In the same time also the supply voltage trace changed: initially it settled to about 4.9 V, with some negative dips down to approx. 4.7 V (asociated to short charging periods that I cannot explain, because I expect here to see a constant voltage coming from the USB port). Then, after 1 h and 50 minutes the supply voltage trace reverses to a floor of about 4.7 V with a series of short positive pulses going up to about 4.9 V. Here long charging periods are indicated. Starting from this moment the Temperature (and thus relative Humidity) traces show a lot of pulse-like artifacts. What is happening? is there something I can do? Thank you very much and best regards. Alberto ---
**Author:** ![robouden](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/robouden/32/336_2.png) [@robouden](https://discuss.blues.com/u/robouden)\ **Post date:** [July 2, 2023, 3:41am UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/2 "2023-07-02T03:41:24Z")
Alberto, Sorry for the late reply. Thank you for the detailed information. I will look into the issue in more details. Regards, Rob Oudendijk. ---
**Author:** ![robouden](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/robouden/32/336_2.png) [@robouden](https://discuss.blues.com/u/robouden)\ **Post date:** [July 2, 2023, 10:41am UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/3 "2023-07-02T10:41:57Z")
Alberto, What USB power do you supply? Can you supply it with battery powered USB? Regards, Rob Oudendijk ---
**Author:** ![AlberTO](https://avatars.discourse-cdn.com/v4/letter/a/ea5d25/32.png) [@AlberTO](https://discuss.blues.com/u/AlberTO)\ **Post date:** [July 2, 2023, 8:44pm UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/4 "2023-07-02T20:44:24Z")
Hi Rob, this was an old problem. My Airnote has been substituted and now it’s OK. Thank you very much and best regards. Alberto ---
**Author:** ![robouden](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/robouden/32/336_2.png) [@robouden](https://discuss.blues.com/u/robouden)\ **Post date:** [July 2, 2023, 10:34pm UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/5 "2023-07-02T22:34:41Z")
Alberto, You use the same power supply for the new Airnote? Regards, rob ---
**Author:** ![AlberTO](https://avatars.discourse-cdn.com/v4/letter/a/ea5d25/32.png) [@AlberTO](https://discuss.blues.com/u/AlberTO)\ **Post date:** [July 3, 2023, 6:58am UTC](https://discuss.blues.com/t/artifacts-in-temperature-and-relative-humidity-readings-when-powered-via-usb-5v/824/6 "2023-07-03T06:58:35Z")
Yes Rob, it’s always the same power supply, a Samsung EP-TA20EWE (5V/2A) Regards, Alberto