AMP1-B & PS317-P

[Rafax-es]

hi,

I've attached the PS317-P at the amp pcb. R1=120ohm & R2=360ohm.

http://picasaweb.google.es/rsantct/A...42347608092818

When I apply +30V to the PS317-P input , it runs ok 5.09V, but the LM317L chip gets very hot (!)

is this normal?, any experience?





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[Scratchy]

The input voltage is too high for this little TO-92 package.
Assuming a 25V drop with 80ma current, means you will be dissipating 2W of heat.
This is operating at the extreme limits of this VR according to the datasheet.

I wound 20 turns of wire around my toroids to use as a 8VAC supply for the 5V regulator.


This also keep the 5V ground isolated from the PS ground as per this post:
http://41hz.com/Forums/topic.asp?TOPIC_ID=22

***It's so easy, everyone should be doing it***

[Rafax-es]

ok, I understand now.. the to-92 gets hot even without load (!)

is great idea to wind some extra turns around the transformer to get an isolated supply!

thanks again!


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[Scratchy]

You must rectify the voltage from the isolated supply, as this Voltage regulator is for DC to DC only. I used a 1N4002 diode as a half wave rectifier with a 1000uF capacitor for input into the PS317. I also added a 100uF capacitor on the AMP1-B where the 5V input connects to the board.

***It's so easy, everyone should be doing it***

[Rafax-es]

ok, thanks, uF are always useful for good voltage quality.

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[Rafax-es]

hi, it's all ready, see the new pcb with dummy loads and rail fuses. Not still powered on, but coming soon...

http://picasaweb.google.es/rsantct/A...52992198698802


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[Scratchy]

Very nice Rafax-es, it certainly looks like you have done this before.
I also suggest you put a 60W light bulb in series with the 240V input to limit current while testing.
I had to build a soft-start circuit for mine, as it would blow fuses due to the in-rush current at power up.

***It's so easy, everyone should be doing it***

[Rafax-es]

seems to be it runs ok

http://picasaweb.google.es/rsantct/A...04209085811010
http://picasaweb.google.es/rsantct/A...04207504850562

and it sounds... ... ... terrific!!!

now I plan to make some extra winds on the toroidal trafo to get an isolated low supply for +5V, coming soon.





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