12 Volt DC to 9 Volt DC?

[ARKPAT]

Just leave out the R1 and R2 resistors on a LM-7809 devise ( same place as LM-317 )and take the ADJUST line to Ground. It will work the same for LM-7805,LM-7812......etc.......fixed voltage circuits. Or you can use the table and the schematic shown above and use R1=100 ohms and R2=620 ohms to have a fixed voltage regulator circuit. Change the 17+ to 12+ and the 13.6 to +9 on the output side of the circuit.



Pat

Sorry; I do not have a capture program to modify the schematic above.

Check the application PDF file for circuits ( sorry, but you curious people here is the designer information stuff ).

[bgeddes]

I tried to post a schematic, it did not work.

Above post is correct.

[ARKPAT]

I had the same problem in posting this one but used the IMG with html in them as instructed in the post messages. But I do not have a screen capture program to modify the circuit.





Pat

[bg]

Somebody let me know if this isn't correct.

[bgeddes]

If you are coming off a battery, skip the 22,000uf cap, it is in the other circuit to smooth the AC off the transformer.

Other than that, it's right. What kind of amperage on the 9v side?

[ARKPAT]

I hope this comes out ok. Playing with Paint program.



Pat

[bgeddes]

That's it ARKPAT!! The 1uF might need adjustment based on current draw but that circuit should work for general purposes.

Note to builders: Don't go crazy looking for exact capacitors, their value is has a lot of 'fudge factor'. For the capacitor on the output side, make sure it is rated for at least 9 volts, (if I built it I would make sure it is rated for 12v, because things happen).

[bg]

I updated mine to be correct - I don't deal with circuits enough to have a vast knowledge of them - though I did wonder why there was a third capacitor involved.