Sushil,

This particular discussion is between you and me for last many posts, so let's use this thread and not use a new one.

As far as bridge is concerned, it has 2 puposes.

1) It will rectify ac to dc, if you use ac adapter/transformer.
2) If you use DC as input to the programmer, no matter what the polarity is, the output of the bridge will always have same polarity.

If you directly apply 12 Vac to the input of programmer, it should function.

The programmer you mentioned (on ATMEL application note) has some limitations, I made it a few years ago. It uses software delays and thus the timings vary from PC to PC. Also it has DOS based control software and can program only one type of the device.Some other limitations are

a) There is nothing like buffer.
b) You can't read a device and save its contents as HEX file.
c) The Program has been written in Microsoft C, so it is difficult to modify since most people have Turbo C or Borland C.

Soon I will add 24Cxx series EEPROMS to Mr. ASim Khan's Programmer. So this programmer will have the added advantage over ATMEL's.

Regards

IA