Why cap is across the resistor in the circuit

[siddharthtaunk]

I would like to know why is the capacitor 1uF 400V is accross the resistor 470KOhm

https://obrazki.elektroda.pl/9884347100_1385465667.jpg



when the resitor is there for current limiting what is the cap doing there

 

[godfreyl]

Re: Why cap accross resistor in the circuit

At 50Hz, the impedance of the cap is much lower than the impedance of the resistor, so it is actually the cap that limits the current.

Now, why is the 470K resistor added across the capacitor? The resistor is there to discharge the capacitor when the power is switched off.

Without it, the capacitor may stay charged to a few hundred volts after the power is switched off. Anyone who touched the pins on the mains plug after it was unplugged could get a nasty shock.

 

[siddharthtaunk]

Re: Why cap accross resistor in the circuit

At 50Hz, the impedance of the cap is much lower than the impedance of the resistor, so it is actually the cap that limits the current.

Now, why is the 470K resistor added across the capacitor? The resistor is there to discharge the capacitor when the power is switched off.

Without it, the capacitor may stay charged to a few hundred volts after the power is switched off. Anyone who touched the pins on the mains plug after it was unplugged could get a nasty shock.

How to calculate the values for the same?
Thanks

 

[fun2design83]

Re: Why cap accross resistor in the circuit

cap is short circuited while u feed 50Hz input, and the resistor is just to discharge the charge accumulated on the cap in the absence of input AC voltage. what do u mean about the values? which values?