http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-07T21:45:57-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t715.html 2009-01-07T21:45:57-08:00 I am getting a sine wave from an band pass filter and using a schmit trggr ckt, i am shaping it as a square wave, i want it to feed to MCU. I am using 89c51 for operating a 12v relay( by generating PWM).Now the problem is that i have to level shift the schmit trigger o/p (1.22v- 1.88v) to a digital pulse (h1gh or l0w) so as to use it to MCU i/p. how can i do this?can u plz help me?Vth+ | |----| |----|1.88vvth- |__| |__| |1.22v _________0v . . .o/p reqd: .__________________1 |_________0_ http://www.8051projects.net/forum-t715.html 2009-01-07T21:45:57-08:00 Ajay use diode clamping circuit.. for level shifting. google it for more information of clamping circuits..