power supply design

[mithila.panicker]

I would like to design a power supply that can provide output voltage of 0-30V and can get a linear range of current upto 0.1mA .The input to it is an ac in either sine wave ,triangular or square wave form. Can anyone help me out?

 

[Dragon Tamer]

here are a couple of circuits you can use to build an adjustable power supply up to 30V DC. although it is my nonprofessional opinion that it would probably be easier to build 2 separate power supplies that have a maximum output of something like 15V and connect them in parallel.

 

[Dalaran]

I think he'd want to connect two 15V supplies in series to get 30V.

 

[Dragon Tamer]

yea you're right, my bad

 

[mneary]

The input to the 723 based power supplies need a DC input voltage that's not less than about 37V (so it can maintain regulation) and not more than 40V, the LM723's rating. The transformer must be between 26VAC and 28VAC from no load to full load. That's a pretty narrow range.

For your desired 100µA output, you don't need the pass transistor, and the LM723 can be connected as shown in the National Semiconductor data sheet, page 6 figure 2. If it's configured without a pass transistor, the input can be 33 to 40VDC, yielding a relaxed transformer spec of 25VAC to 28VAC.