I need help analyzing it. Firstly, I haven't quite understood the operation of the precision full wave rectifier in the circuit. When I simulate it on Multisim, I don't get a full wave rectified output across the diodes. Is it a full wave rectifier? This is the designer's explanation of the circuit http://amasci.com/viselect/vistxt.html
Secondly, what is the function of the transistor 2N3904 in the circuit? Thirdly, it's output goes to a series of NAND gates, whose function I am unable to figure out.
I will greatly appreciate any help you guys can provide me.
Thanks.