# Problem with EEG trigger from photodetector recording when importing on Eeglab

**URL:** <https://psychtoolbox.discourse.group/t/problem-with-eeg-trigger-from-photodetector-recording-when-importing-on-eeglab/5716>\
**Category:** Hardware\
**Created:** [May 28, 2025, 9:38am UTC](https://psychtoolbox.discourse.group/t/problem-with-eeg-trigger-from-photodetector-recording-when-importing-on-eeglab/5716 "2025-05-28T09:38:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lpeintur](https://avatars.discourse-cdn.com/v4/letter/l/e8c25b/32.png) [@lpeintur](https://psychtoolbox.discourse.group/u/lpeintur)\
**Post date:** [May 28, 2025, 9:38am UTC](https://psychtoolbox.discourse.group/t/problem-with-eeg-trigger-from-photodetector-recording-when-importing-on-eeglab/5716/1 "2025-05-28T09:38:11Z")

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Hi,

I am preparing my experiment that uses an EEG equipement with dry electorde (wearable sensing) and a photodetector linked to triggerbox to setup trigger.

On the EEG software I can see that the trigger is well detected but when I make a recording and import it to EEglab, the plotview indicates that there is no events.

I am learning on my own and it’s quite difficult, could someone explain if that’s a problem or maybe it’s because as I’m using an analog input for the trigger, it’s not detected as an event in EEglab but the trigger waves has been correctly recorded ?

Thanks in advance,

Léo

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**Author:** ![Ian-Max-Andolina](https://yyz2.discourse-cdn.com/free1/user_avatar/psychtoolbox.discourse.group/ian-max-andolina/32/4_2.png) [@Ian-Max-Andolina](https://psychtoolbox.discourse.group/u/Ian-Max-Andolina)\
**Post date:** [May 28, 2025, 9:39am UTC](https://psychtoolbox.discourse.group/t/problem-with-eeg-trigger-from-photodetector-recording-when-importing-on-eeglab/5716/2 "2025-05-28T09:39:00Z")

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This is not directly related to PTB, so you may not receieve much help here…