Moderate yourself when giving a talk

Recently I had the chance to record a small series of video trainings for future Android developers. During the recordings I encountered the problem that I slight problems with restricting my speaking time to certain limits. Restricting the time of each lesson ist pretty important since the average time span a human can fully concentrate is also very limited. But in some lessons I just kept on speaking. I started to explain interesting but unecessary details and instead of about 12 minutes some lessons were suddenly half an hour long.
So I started searching for an app to solve my problem.. Countdown timers semmed impractical since I didn't want to stop the lesson abruptly but have the ability to see how much time has passed and if I'm over a certain warning level.

First I started using the stopwatch on my Galaxy S3. But the numbers were too small and I didn't had any optical notification. So I started writing my own app. It is a minimal timer which just shows the passed time, keeps the screen on and gives you some optical feedback if you speak too long. It is simple and elegant and as soon as I have catchy name and a logo you can get the app in the playstore.