URGENT HELP _PIC16f877

hi there guys. I was taking a look at a microchip application note An236 and was wondering if you could help with the following:

I am going to attach the document on this message. Please take a look at it especially at the circuits included in the appendix especially circuits 5 0f 5 and 3 of 5.

Can someone please explain thses circuits in detail to me, how they work, how to design circuits like this from scratch ie. what to look for, what formulaes to use and finally how you would determine the value of the components used. I especially need help understanding circuit 5 0f 5. Would someone be able to simulate it and explain to me what the waveforms at the different points in this circuit look like and why? What is the purpose of the 5 inverters that are used in this diagram?

View attachment 00236a[1].pdf

Help please.....its really really urgent.........appreciate all the help i can get

sheet 3 of 5 shows and does exactly what it says. A power supply from the mains AC converted to 5 V DC (without the use of a transformer)
I think you should google for op amp circuit tutorials and highpass circuits to undestand what the components do.
here is one..
**broken link removed**
hope that helps while your waiting for more indepth replies.

I've not built the Microchip X10 16F877 app note myself but I do recall seeing posts that the 120kHz filter design was duff.

Why is it Urgent, you can just go buy RS232 to X10 devices.