Thank you for your reply. I would like to know the difference between stepping down voltage ( bridge rectifier ) thn Bridge rectifier and Rectify AC thn DC - DC step down conversion ??
The two really are not related.
You don't need a bridge rectifier for a DC to DC converter, you need a DC power source.
These are the proper arrangements;
AC power in to Step down Transformer, bridge rectifier, Filter, DC out.
DC in to DC - DC converter, DC out.
You can use a DC - DC converter after a DC power supply to change the voltage if you want.
Thank you . Actually my input is 12 V AC . I want to convert into 3 V DC . may be i should use Rectifier + DC DC converter , since my input is low . am i correct ??
Depends on cost and efficiency needs as well as power demands.
A traditional full wave power supply may be cheaper, and easier to get higher currents out of.
A DC/DC converter is more efficient but harder to get higher currents out of.
A traditional full wave power supply is easy to make your self.
A DC/DC converter can be complicated with harder to find parts.
What voltage and current do you need out of your 12 volt AC supply?
my supply is variable voltage between 6 - 12 V AC , different frequency but less than 200 Hz , current 10 - 100 nA and I want to convert it in to DC 3V , cost is not an issue .
Thank you . Actually my input is 12 V AC . I want to convert into 3 V DC . may be i should use Rectifier + DC DC converter , since my input is low . am i correct ??
Thank you its really helpful . I am looking for both because i have doubt weather to implement DC - DC buck converter or use Step down transformer ? your solution is perfect , Ty
No exactly the opposite. Any active ciruitry such as switching regulator needs about a thousand times more power to operate than what you have available. You need a completely passive solution with as little leakage as possible. Stick with a single low leakage diode as a rectifier, and a second zener diode to clamp the voltage. Fedd the result into a very low leakage capacitor.
I have no idea what are you trying to power, but I dont think your source will be able to power anything. Can you give more details about what is that mysterious power source and what you are trying to do with it?