Help with Bipolar supply

[tom42107]

I was wondering if this was possible. I've made a few 6.3 and 12.6vdc regulators with a LM317 and they have worked well. I now want to modify a bipolar supply I built to include a 6.3vdc regulator. Just wasn't sure how it would affect the rest of the supply. Still learning.

Tom

 

[Emerson Prado]

I assume you transformer is connected in the right side, into the rectifier bridge. The only effect I can think of is the regulated supply would draw current from the main one, so this should be able to stand that. Of course, any noise introduced by one supply's load will affect the other.
Best regards,
Emerson

 

[KatieandDad]

I concur.

You will be adding extra load to one side of the +/- supply but as long as it can handle the extra current it will work.

In true audiophile fashion though, if appreciable current is being drawn through the extra circuitry you will unbalance the +/- supply.

In English. If the unloaded +/- supply gives you +/- 12V; unregulated the +/- 12V will drop slightly as you apply a load.

If you load one side (in this case the +ve) then the unregulated +/- may become +10V and -12V.

This wont seriously affect most circuits but you might prefer to regulate all the supplies to keep them constant.

 

[Osvaldo de Banfield]

I can suggest you to add a small cap (10uF) from adj pin of LM317 and earth, and two diodes, one of them from input to output (Cathode to input) (for protection from reverse voltages, if the input cap discharges quicklier than output, and one more from out to adj, cathode to out (Idem) See the National or ST data sheets at digchip.com or any other source. There, you can find more tries to do.

 

[tom42107]

Thanks for the tips. Very helpful.

Tom