Help me in analyzing the circuit diagram of 12v dc UPS!

[ganeshrnet]

I've designed a 12v DC UPS.. Anyone good at electronics kindly analyze the circuit i've designed in the image tagged,,, If you feel any problem, kindly help. Also please check for the values of the components used..
Is there any quick transistor switch by which I can replace the BC148B and SL100? as all know the ups need to be very quick... Please help..

 

[RetroTechie]

Other than DC resistance of transformer coil, I see nothing to limit voltage or current for the battery. Basically you're just rectifying AC & put that across the battery? I have a feeling most batteries might very much not like that... :evil: What battery type do you plan to use?

Also I don't see why you wouldn't use some sort of diode construct to connect battery to same point that you use for regular DC input (the unregulated 16V across C1). Putting battery on other half of transformer winding (and use transistors to switch over) seems more complicated than necessary... Then use that with AC present DC voltage > battery voltage to trickle charge the battery?

With a center tap available on the transformer, you can use the bridge rectifier a little different, so that you have only 1 diode voltage drop (and distribute currents evenly over halves of the transformer winding - read: higher DC voltage to work with, lower losses in the transformer).