Design Dual DC Power Supply: 0-20V, 0-1.5A, User Selectable

[Julian Wong]

Hi,i really need help on how to design a dual channel DC power supply that fulfills the following specifications :

1) Operation - User selection between independent adjustment for positive and negative output voltage, and series tracking mode (slave channel tracks the master channel)

2) Output voltage amplitude : 0-20V± 5%

3) Current limit : 0 - 1.5A± 10%

4) Powered Directly from main supply

5) Indications of power on, constant voltage and constant current mode

I really hope you guys will be able to help me and provide me with a schematic to achieve the above specifications..thanks in advance =)

 

[Julian Wong]

I have found the schematic from this link http://www.aaroncake.net/circuits/supply3.asp
but i would like to know how to make the circuit to produce an output voltage of 0-20V instead of just 0-15v?can anyone give me any helpful suggestions?

 

[jim hardy]

that schematic should produce from 1.2 to 27 volts.

check datasheet for your regulator.
http://www.ti.com/lit/ds/symlink/lm117.pdf

EDIT make that "that schematic should produce from 1.2 to about 19 volts.

what limits it to 19V is volts available from transformer.
15 X sqr(2) = 21 volts, less drop across bridge.

use a higher voltage transformer, something like this:
http://www.allelectronics.com/make-a-store/item/TX-398/POWER-TRANSFORMER-39.8V/22.5V-2.25A/1.html [Broken]

and you should do fine.

 

[Julian Wong]

wow..thanks a lot..appreciate it =)