I'm not sure how to use the schematic function with stack exchange so I'll be posting these pictures. I wanted to repurpose the circuit in a fly zapper to make sparks. I drew a circuit I saw from the board to match the reference circuit I found. I want to know why they have added an extra capcitor and resistor to the circuit.
The capacitor is there to provide additional ripple smoothing.
The resistor is there to discharge the capacitor when the circuit is powered down.
They are commonly referred to as "Bleed Resistors".
Usually they are for user safety. The capacitor could retain enough charge to cause an electric shock for a long time after the circuit is powered down. The resistor is selected to discharge the capacitor to a safe voltage after a few seconds.
The value of the resistor in the diagram (82K) seems rather low considering the voltages and would dissipate a lot of power. What is the value of the capacitor?