Quote Originally Posted by Melanie View Post
Actually my point was that in the first schematic the H11L1 is providing isolation from the supply to the 555, in the second it is provided by the Transformer - which makes it kind of pointless having it still in circuit. Also that Transformer is 12-0-12... is there a reason you want to run your Trigger circuit at 24v?

Blindly copying other peoples schematics is one thing... but modifying them without actually knowing what they do is another (kinda like all the cut & paste that goes on in this forum I suppose)...
I am developing a remote control system using microcontroller, my project is not only control fan regulators, its also control lamps etc. So I add more than 10 relays for switching lamps. My all relays are using 12v. So the 12volt transformer is using for other purpose also like relays etc not only for above mentioned schemetic.