CMOS gate with floating input

You can not depend on a floating output with no control. I have attached an appnote on oscilators.

Thanks for your quick reply. Actually my requirement is not an oscillator. I need to detect a wire cut ( open wire) in a circuit. I have a microcontroller board which will get an external input of 12v. I need to detect whether the 12v source is on or off or the wire has been tampered. To distuingish between off and wire cut i have used a cmos gate. The cmos gate will give ( CD4093) low when 12v present and high when 12 is off and give oscillation when the input becomes open.

Do you have any other idea to fullfill this requirement?

Take another CMOS gate, conect its output to the 12V input you are sensing but with a series resistor of 4K7. Toggle the input of the additional CMOS gate, if the output of the 12V sensing gate also toggles, the cable is cut. 

Thanks for your reply. Actually i could not understand your idea. is it possible to put your idea into  a simple schematic form which will help me to understand easily.

Something like this

You are welcome!

Glad to hear that it worked