[SOLVED] [moved] I want to allow voltages in a particular interval

[dhasvan]

In my circuit there is a voltage source which is providing -12V, -3V and +6V but I do not know which will be. Without knowing I want to design a circuit with diodes which will allow current for every specific voltage value. i.e if the source is -12V it will go from one rail, if it is -3V it'll go to another and so on. I thought of a system with zener diodes however I could not set it for the intervals. I can make it happen for the values smaller than -6V or larger than +6V but when I have to choose intervals it fails. I mean i could not make one rail to let votages for 0<x<-6. Is this possible, if so, how? Thank you for your time and answers.

 

[BradtheRad]

There is a way to arrange transistors to trigger one another on/off, depending on the supply voltage. (The diagram illustrates the concept, although you'll have to experiment with it.)



Or a simple method is a bunch of window comparators. This allows you to set a variety of different ranges. The concept requires a single control unit. Perhaps a 3914 IC (10 level).

 

[dhasvan]

Thank you for your response. I have to do it without using transistors or other modules. Is it possible to do it with just using OP-AMPS and diodes. I couldn't figure it out. Thank you for your time.

 

[dhasvan]

I did it with comparators like you said thank you for the idea.

 

[andre_luis]

As Brad said above, what you need is called Window Detector.
A theoretical model can be seen here: https://en.wikipedia.org/wiki/Window_detector

 

[dhasvan]

Thank you for your response. I did a similar thing but with this i will probably make my circuit efficient. Thank you again.