Loss of Power protection system ???? Any ideas???

[Brettski]

Hi guys,

Need to design a circuit to do the following :

When a loss of power 220VAC happens, a timer must activate for x seconds (from 10s - 360s) then activate a relay for 3s which drives a 12VDC Coil at 1.5A.

Here is what I have (correct I hope!)

220Vac - 12DC 0.3A Battery Charger
7Ah Sealed Battery
I have a CD4541BE connected to a 4700uF Cap which keeps a charge long enough for the timing circuit but the timer only activates my relay not latching off.

The circuit works but I cannot think of a way to turn off the relay??

Thanks...

PS The battery charging circuit is to make sure when the power goes back on the battery is trickle charged...

 

[Roff]

Hi guys,

Need to design a circuit to do the following :

When a loss of power 220VAC happens, a timer must activate for x seconds (from 10s - 360s) then activate a relay for 3s which drives a 12VDC Coil at 1.5A.

Here is what I have (correct I hope!)

220Vac - 12DC 0.3A Battery Charger
7Ah Sealed Battery
I have a CD4541BE connected to a 4700uF Cap which keeps a charge long enough for the timing circuit but the timer only activates my relay not latching off.

The circuit works but I cannot think of a way to turn off the relay??

Thanks...

PS The battery charging circuit is to make sure when the power goes back on the battery is trickle charged...

I don't know about the other guys on this forum, but I personally have difficulty mentally converting a functional description and a handful of parts into a meaningful schematic. Can you post one?