turning an unregulated PSU into a regulated PSU

[rob_gould]

Hi all,

I wanted to buy a 9V 5W regulated PSU from here to power a very simple project I'm building.

http://www.jprelec.co.uk/store.asp/c=1633/Power-Supplies-PCB-Encapsulated

Unfortunately the reg version of the PSU is out of stock and the lead time is over a month.

So, my question is can I buy the same spec PSU but put an appropriately sized voltage regulator between the PSU and my circuit to make it regulated? 7809 is the part I was thinking of. Or would I need to use a bigger PSU, 12V say, and then regulate down to 9V?

In case it makes any difference, the circuit is a very simple monophonic synth and guitar delay pedal circuit all in one box. The delay pedal circuit contains a 7805 but the bread boarded synth circuit doesn't have a regulator...

Cheers

Rob

 

[JohnRoberts]

Yes, 12v unregulated should work to make 9v regulated. Look at the data sheet for regulator to find drop out voltage. Add this drop out voltage to the nominal output and that will tell you the minimum input voltage. Unregulated supply will have ripple so bottom of the ripple trough needs to be above drop out voltage.

JR

 

[rob_gould]

Just the ticket - many thanks JR