switch between two power supplies

[talhauzair]

hello,

I have two DC power sources primary and secondary, i need circuit which should simply turn my primary power off when it gets lowere than some given voltage and turn on secondary power, and again turn on primary when it gets higher than same given voltage.
same type of circuit is installed in ups also

please help

i want to install this circuit in my solar system as solar power will be my primary source and dc adopter will be my secondary source.

 

[D.A.(Tony)Stewart]

those requirements may be defined too simple for optimum storage of solar power and discharge when power is interrupted, but basically one diode in each circuit aso known as " diode OR" logic, passes the higher voltage to the common cathode.

 

[talhauzair]

hello.

Thanks you for you reply i am not very good at electronics please help me through any schematics or witch exact components name required

 

[Surender Reddy]

Make voltage divider for your power supply, and connect the output to the adc pin of any micro controller, and code the uc as per your requirement.

 

[chuckey]

Simplest solution as per Sunnyskyguy's response. If you are using low voltage, silicon diode will drop .8V, while germanium drop .3V, so are the best to go for.
The most sophisticated solution is to have a diode derived " Aux line". This then powers an opamp which accurately compares the two power sources and uses a relay to switch from one to another (no voltage drop). Do not think of using a micro processor in this application it offers no advantages over wired up logic and starting from scratch, is very expensive.
Frank