Can combinations of zener diodes be used to activate a certain circuit if input voltage is between 30 Vdc to 20 Vdc and to activate other circuit if it were between 20 to 10 vdc? If it can be, I hope to use it for limiting difference between Vin and Vout for LM350.
sureshparanjape

 

This can be done, but you must provide more info, circuits, calculations, and specification.

 

A Window Comparator?

Is this for DC only?

 

The usual, very little information provided for a question with many possible answers.

 

Thanks to all helping hands.
If I don't get all my thoughts just they should be, it is because I am just a beginner in electronics. I have only one aim - to enjoy joy of learning electronics hard way- that is working on a circuit.
So I first have picked pip this circuit based on LM350. Reading the comments of experts and beginners(like myself), I have formed an opinion, may be very wrong, that LM350 could get heated if difference between Vin and Vout is "large". I have a transformer,12-0-12, which gives rectified DC voltage 34 or 17. I am therefore of using two identical circuits, which uses one LM350. I wish to use one circuit if the output requirement is between 15 and 30 and other if output requirement is between 1.2 to 15.
If I may further add that how does one decide what kind of load, a given circuit, would give the power source; must be by some rough calculations. I imagine one can do it by finding all parallel circuits, determining current requirement for each and so on. Thanks again. sureshparanjape

 

It seems like you may have better results if you use TWO voltage regulators...one for each range of voltage you are trying to obtain!

LM317 will work fine for up to 15V - I would begin there, and design your power supply for low voltage. Then find an equivalent regulator rated for over 30V, and build the second one!

Search on here for "regulated power supply", or LM317...there are many projects that were built with that IC....easy to use!

 

Keep in mind how much current you will draw from your circuits, as well...and you will need a heat sink on the LM317 to dissipate heat...