I did navigate on how to choose a proper capacitor, whereby i did learn that the capacitor voltage to be chosen must be equal to the voltage supply or higher, in terms of charging voltage. I also came across, that a resistor in series is also a good practise as to reduce the high current initially to the capacitor. Can anyone confirm if im right?
The led (with the 330 ohm resistor) can be connected to a pin of the Arduino.You don't need a transistor driver for that.
The 1N4749 has no use at that point, please remove it.
I don't know the HJ A42, what is that ?