Help Solve a Clamper Problem - No Homework Involved!

[PainterGuy]

hi everyone,

please help me with this clamper problem and please also note that it has nothing to do with home work. if i understand this problem i can understand the overall function of any clamper (at least this what i think ). please take a look on link "1". it has also my questions there. we start from where the capacitor s fully charged. i have drawn that point on the diagram (well i can be wrong, so take caution ). i wouldn't repeat my question here because i believe you will understand them better there on the diagram.

one question i will ask here: what is R doing there? i mean what is its function?

1- this is the modified diagram: http://img860.imageshack.us/img860/359/ex28modified.jpg
2- this is the original one: http://img833.imageshack.us/img833/7397/ex28original.jpg

i will be very much grateful if you will help me out with this problem. please don't confuse me.

cheers

 

[PainterGuy]

i didn't know it will take that much time to receive help here, a place full of geniuses and good people!

 

[chahat]

Hi.. i think this could be a bit useful for getting the answer to the use of resistance in the circuit..A Clamper circuit uses a capacitor, resistor and a diode to fix an ac waveform to a DC level. This is accomplished by the quick charging of a Capacitor through a diode but the discharge path is through a large resistor. Due to RC time contants, the capictor is not geven enough time to discharge befor the next charge arrives thus acting as a voltage doubler. TC= Time Constant = Resistance in Ohms times the Capacitance in Faraday that is measured in seconds. It takes 5 Tc's to fully charge. By adding a DC Bias, we are now able to set a new clamping point other that the 0 Volt reference.