Lightning shutter trigger - additional pictures

After a first thunderstorm, a second one allowed my son to take additional pictures. This time, he hunted the storm with a friend of him, who had bought a commercially available trigger some time ago. This was a good opportunity to compare my trigger with a commercially available model. Consequently, I was eagerly waiting for my son to be back from his hunt. 

And here is his feedback: distant flashes were not detected by my trigger, while they were detected by the other one...

Actually, I hesitated quite a lot during the design phase: should I amplify the signal coming from the photodetector, or use it as it was? I decided upon the second alternative, mainly for simplicity and cost reasons. Now, it seems that if I want to be as good as some commercially available models, I should add an amplification stage...

Anyway, for now, here are some of the pictures my son took on this second hunting day:

Camera: Olympus E-420 - Exposure time: 1/160, aperture: 11.0, focal: 14.0 mm - time: around 6:00 PM.

Location: near Draguignan, south-east of France.

Below are some additional pictures, without lightning flash, but with some interesting cloud shapes:

A few more pictures.