Stopping Power Supply to Lasers

I came back to Factorio this week after a good few months away. As I reacquainted myself with my base, and made sure that my power supply was looked after, I stumbled across some of my attempts at making some laser turrets lose power when there was nothing to attack, and get power again when they were being attacked. This seems to have been the best I could put together https://i.imgur.com/e8Mps7D.png

It uses (what I think is) an S/R latch to connect to the main power when the accumulators get drained to a certain point, by the 4 active lasers in the centre. At this point the power switches for lasers on the left, and right get activated. The bugs then get blasted, hopefully.

It doesn't work as well as I would like. Aside from the addition of some walls, and some bots to repair and replace. Does anyone use anything similar that does the job better, or have an suggestions for improvements?