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Topic: Voltage Controller (Read 2 times) previous topic - next topic

baum

So is a relay actually the easiest?

pwillard

Technically, a Voltage regulator is an OP AMP with a voltage reference.  Look at the design of a legacy LM723.

http://www.national.com/ds/LM/LM723.pdf

I think you are thinking about this too hard. You are describing regulator "drop out", which a regulator like a LM7805 will want to do somewhere between 6 and 7 volts.

Now, if you wanted to do this with a little bit more control... start looking at circuits based on the LM431.  IN the design ideas section of the data sheet, there is "Over Voltage/Under Voltage
Protection Circuit" or a "Voltage Monitor" as good ideas to think about.  http://www.national.com/ds/LM/LM431.pdf

...and "no"  using a relay is not a good idea.  It makes the solution too complicated.  Simply pinching off a PASS TRANSISTOR is probably the best solution.


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