Digital transducers

A digital transducer comprising:

• a container;
• two disparate materials in said container defining an interface therebetween, said interface being movable through said container responsive to a force applied to one of said materials;
• a plurality of means spaced along said container for sensing said interface, each of said sensing means responding to the presence of one of said materials;
• means coupled to all of said sensing means for electrically suppressing outputs from all of said sensing means responding to said one material except that one sensing means which responds to said one material and is nearest said interface, said output suppressing means comprising a plurality of active circuit elements, each having first and second terminals and another terminal for controlling current flow between said first and second terminals, one of said first and second terminals of each circuit element being coupled to the output of one of said sensing means, said control terminal of each said circuit element being coupled to the next adjacent circuit element at said one terminal of said first and second terminals which is coupled to the output of the corresponding sensing means;
• and means interposed between said control terminal and said one terminal of said next adjacent circuit element for allowing current flow therebetween only in one direction.