Lm317 Reg

[geowhitt]

Hi i have just started building a power supply for my Naim 62 pre amp.
I did want to use a hicap but the cost has gone stupid so i am building one.
I have a transformer a case and i have also bought some lm317 regs, were i am stuck is knowing what resisters to use to set the volt out put, i was looking for 25v.
If anyone know which resisters to use please let me know,or anyone selling a hi cap.
Many thanks.
George.

 

[Calvin]

Hi,

load down the datasheet of the LM317. Everything from the formulas up to circuit examples is written in there!
http://www.alldatasheet.com/

jauu
Calvin

 

[justblair]

Google is your friend on this...

Online calculator

This is one of several online calculators that will do the math for you..

The R1 tends to be set at 240R. I cant remember the criteria for selecting this value, I think its either in the datasheet or design application notes. Basicly though 120R to 240R work ok.

I am sure there is an online calculator that allows you to set your target voltage and derive R2, but I only searched for lm317 online calculator and chose the first one. If you take a little longer you might find it.