hi there, this is my first post here.

I am trying to figure a way to use analog to digital converter IC (adc0808) with an input signal that is not TTL compatible. The datasheet shows that the input signal must be TTL while my signal is 12V.

Can anyone think of an accurate way of conversion? Thanks alot in advance.

 

The only thing that comes to mind is a line receiver such as a 26LS32. They come four to a package, you can set the threshold, and the outputs can be tri-stated.

 

http://chaokhun.kmitl.ac.th/~kswichit/ap275/ap275.htm

Modern version of the 26LS32
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1852

 

An op amp with a gain of ~0.416.