variable power source design - help needed

[sindrix]

variable power source

i have to design a circut that will produce 5v, 9v, 12v, 24v,and 30v. basically a varible voltage source any ideas where to start

 

[hameeds01]

Re: variable power source

whatz ur current requirement ??

 

[apurvmittal]

ya..
once u knw the current requirement..u can start with a
1) rectifier 2)filter 3)voltage regulator

Rectifier : since u r designing a power supply, ur input will be the ac power. Inorder to convert the ac power to dc power, u must use a full wave bridge rectifier. This recgtifier requires a center tap transformer. since ur maximum supply is 30V,u can use a separate transformer for 24V and 30 V outputs. This will reduce the heating of power supply as then power wont be wasted in case u wrk with lower voltages. The rectifier uses 4 diodes and u will get circuit easily frm internet. the voltage ratings for the commercial diodes are normally much above the drops across them for voltages u r wrking on..

 

[nashwan]

hi
wat the input for ur power supply its power line using transformer or batt?
wats current u need ?
u talk abt 5v,9v,12v,24v and 30v and then say variable voltage source

u mean here ur power supply with 5 outlet....... 5v,9v,12v,24v,30v
or its just variable from 5v to 30v using pot
or its variable in step from 5v,9v,12v,24v,to 30v using selectore switch

if its 5 outlet u can start with chip like MC7805,MC7809,MC7812,MC7824,for 30v can use LM317
if its just variable with pot u can use LM317, 1.5A or LM338, 5A
if its variable in step u can use LM317 or LM338 with selectore switch type
single pole 5 through to multiply output voltage