Well I ordered 3 of the units Inertia suggested as the cost was pretty cheap. They were delivered from the UK and only took 3 days .
The aim of this Little project as I think has been mentioned before is.
At show we attend we have the Have a go boats to try to interest the public, and hopefully the young to take up the hobby, if not know , then later. We find that this is very popular . Another of our group has built a stand to take 3 transmitters so that they are not being swung around every where , these will be powered by 1 12v Car Battery. A standard egg timer was going to be used, however I stupidly suggested that we could come up with something more technological and after a set amount of time would turn off the power so that they all get a chance to play as we do find some public do hog them, I was given the task to sort it..
The instructions...there were none provided, and the wiring diagram did not really explain it to me, so I went on youtube and found a similar device and was able to back engineer it.
Here is a video of it working
https://www.youtube.com/watch?v=QGaIqNm0_kA&feature=youtu.be