Battery backup with charger Ckt

[yagtoby]

My electronic circuit (CMOS IC based) draws maximum 20 mA and needs minimum 6V. The circuit application requirement calls for a continuous operation. As of now it is running through step-down AC (240V) to DC (6V) circuit. I tried the circuit with Ni-CD & Ni MH batteries and they last only for a few days. I am looking for a battery backup circuit which can drive the circuit during AC power – off conditions and auto battery charging and cut-off during AC power-on conditions.
From the net, the circuit **broken link removed** appears to meet my requirement. The MOSFETchip being surface mount type, somehow I feel difficulty in handling them and its availabilty is doubtful for me. Could somebody suggest me :
- Any other simpler circuit meeting my requirement.

thanks in advance.

 

[ericgibbs]

My electronic circuit (CMOS IC based) draws maximum 20 mA and needs minimum 6V. The circuit application requirement calls for a continuous operation. As of now it is running through step-down AC (240V) to DC (6V) circuit. I tried the circuit with Ni-CD & Ni MH batteries and they last only for a few days. I am looking for a battery backup circuit which can drive the circuit during AC power – off conditions and auto battery charging and cut-off during AC power-on conditions.
From the net, the circuit **broken link removed** appears to meet my requirement. The MOSFETchip being surface mount type, somehow I feel difficulty in handling them and its availabilty is doubtful for me. Could somebody suggest me :
- Any other simpler circuit meeting my requirement.

thanks in advance.

hi,
Have a look at this forum link.
https://www.electro-tech-online.com/threads/battery-charger-design.30011/?highlight=battery+charger

The link you have posted seems to be a complex circuit for what you have in mind.