Capacitor application for battery charging

Thread Starter


Joined Apr 20, 2013
hi, everyone i need your help....
I am working on a project and i have a fluctuating dc power source varies from 0-30 volt. and I am using a high microfarad capacitor to store this energy. I am thinking about making a circuit which let me charge this capacitor to 12 volt and discharge it to 5 volt. and doing this process again and again. used for battery charging
please help me to make circuit switch which automatically remains on after 5volt to charge capactor to 12v and gets off. and another switch between battery and cappacitor which remains on after capacitor charged to 12v and dicharges till 5volt and gets off.


Joined Mar 14, 2008
What is a "fluctuating dc power source"? :confused:

What is the purpose of charging the capacitor to 12V and then discharging it to 5V? There is no advantage to doing that. You will not gain efficiency.


Joined Aug 23, 2012
I'm not sure what is your purpose, but it seems that you can using Op Amp LM324 or
comparators LM339 or LM393 and the transistor or MOSFET to solve your problem.