increase storage time of current

[Rajashri.Shevale]

hii...
I am developing a circuit that will run on AC Supply and after AC is off , it will automatically switch on dc battery. For that i am using DPDT relay. But i am getting a minor problem while doing this...
when it is switching from AC to DC , my circuit is going off for microseconds and then it switches on DC.
So what should i do , to run my circuit contineously without getting off??:roll:

 

[xenos]

Use larger electrolytic capacitor to allow some milisec without power (till relay makes contact), or use a schottky diode in series with the battery (given that the DC produced by AC supply is greater that Vbat).

When AC exists, AC supply power the cirquit, otherwise the battery thru the diode.

 

[ark5230]

What is the average load current drawn from the supply.
of it is not too high there could be many solutions.

 

[Rajashri.Shevale]

my circuit is taking average current 2.5A

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i have tried with high electrolytic capacitors(2200uF,63V)in parallel configuration but still it didn't work.

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i am not getting how shottky diode will helpful in this situation? can you plz elaborate....

 

[ark5230]

Current requirements being high, the slow switching time will demand too high a capacitance.
The best possible alternate I can see could be using a triac or SCR for the purpose of switching. These are fast enough and capable of handling much higher currents.