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[SOLVED] Auto Swicth Power Supply

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DianWardiana

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Hi,

I have a circuit like this:
auto switch.jpg

My question is there a better and more reliable circuit than the circuit that i use now?

Regards
Dian
 

Are there times you find that D1 is necessary? Or to put it another way, Do you find there are times when current tries to travel back to the main power source?
 

is it safe if i'm not use D1?

regards
Dian
 

Hi,

is it safe if i'm not use D1?
Click to expand...
We don't know.

Is there any other load connected after the switch that may drain out the battery?
Is there the possibility that the switch is ON while the main power supply is OFF...and something is draining out the battery in this case?

*****
You could use schottky diodes if you want to reduce the voltage drop.
You may use "ideal diode" circuits to further reduce voltage drop.

Klaus
 

There is no load connected after switch.
and yes there is the switch is ON while the main power supply is OFF. i have load in the resistor. but actually that's not a resistor.

i'm not problem with drop voltage about 0.5-0.7V. so this circuit is rigth?

Regards
Dian
 

Hi,

Yes. Use the circuit with two diodes. Like in post#1.

***
Do you know that most of the power is consumed by the resistor? More than three times than the blue LED takes.
You could easily safe 70% of your battery capacity (size, cost).
In detail it depends on the LED specifications.

Klaus
 
Hi,

LED and resistor in the circuit is imagery.
Actually i have about 12V 3A in load.

Many thanks for you.

Regards
Dian.
 

Hi,

LED and resistor in the circuit is imagery.
Actually i have about 12V 3A in load.
Click to expand...
Very late information. It really matters if the load is 3V/20mA (60mW) or 12V/3A (36.000mW).
Please give those informations with your first post next time. It saves time - for you and for us.

--> If you ask me - I don´t like this circuit for a 3A application. Just because of the generated heat.

Klaus
 

Hi,

I apologize for the late information submitted. Next time i will give all information in my 1st post.

Regards
Dian.
 

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