Building a symmetrical psu B1 buffer - Page 171

Salas · 11th July 2010, 07:09 PM

Next step is 600mA per side then 2A, for enough perceivable niceness. But 200-250mA is the main chunk. Then up it goes diminishing returns.

P.S. Post in 1024x748 links from now on (don't forget to kill the .th in the link else its thumbnails), the server takes refresh to auto resize, and big photos hinder browsing for people on laptops. I am gonna fix the above pics.

udailey · 11th July 2010, 07:10 PM

Got those big sinks ready?

Salas · 11th July 2010, 07:13 PM

Hey, you can have your buffer, and the feeling (plus electricity bill) of running an F5 with one move!

wushuliu · 11th July 2010, 07:17 PM

How do I check Vout w/ my DMM? Forgot about that part...

Salas · 11th July 2010, 07:22 PM

You mean the reg's Vout? You can touch the 3rd pin of the Mosfets nearer to the relay with one probe, the other probe earthed. Or the left most pin of the left audio 2SK then the right most pin of its mate.

wushuliu · 11th July 2010, 07:30 PM

Quote:

Originally Posted by Salas

You mean the reg's Vout? You can touch the 3rd pin of the Mosfet nearer to the relay with one probe, the other probe earthed.

Yes, thanks Salas!

So would any other changes be required to try 600mA aside from larger sinks?

Salas · 11th July 2010, 07:32 PM

Just big size sinks. Under 1C/W per pair. You check voltage across Rset and you divide by Rset's value. If it gives 0.6A, then that is what you got.

pchw · 11th July 2010, 08:05 PM

From my experiment, the most noticeable improvement was from 60ma to around 120ma. After that, the only thing that I could feel going up was the temp. So, I settled on 140ma. I also found keeping the FETS too cold didn't sound as good as keeping them at 40C and upward. Mine are at 45C inside the (old external SCSI HD) case.

regiregi22 · 11th July 2010, 08:10 PM

Quote:

Originally Posted by wushuliu

Yes, thanks Salas!

So would any other changes be required to try 600mA aside from larger sinks?

I would place bigger resistors. Imagine you are using 10ohm resistors. That's about 250ma, so 0,625w aprox. We use 5w resistors for long term accuracy.
If you use 500ma with a 5ohm resistor, that's about 1.25W. So I will use something bigger than 5w if possible.

wushuliu · 11th July 2010, 08:25 PM

Quote:

Originally Posted by regiregi22

I would place bigger resistors. Imagine you are using 10ohm resistors. That's about 250ma, so 0,625w aprox. We use 5w resistors for long term accuracy.
If you use 500ma with a 5ohm resistor, that's about 1.25W. So I will use something bigger than 5w if possible.

Thanks Reg. I'll stick w/ the 10 ohm then. Doesn't sound like there would be much to gain from going lower.

11th July 2010, 07:10 PM	#1702
udailey Passive Aggressive diyAudio Member Join Date: Mar 2008	Got those big sinks ready? __________________ You can purchase LDRs anytime to build a standard LDR attenuator or to build my new LDR Attenuator "A Lighter Note". Email me. diyldr@gmail.com

11th July 2010, 08:05 PM	#1708
pchw diyAudio Member Join Date: Apr 2006 Location: Fremont, California	From my experiment, the most noticeable improvement was from 60ma to around 120ma. After that, the only thing that I could feel going up was the temp. So, I settled on 140ma. I also found keeping the FETS too cold didn't sound as good as keeping them at 40C and upward. Mine are at 45C inside the (old external SCSI HD) case. __________________ - Fred -

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11th July 2010, 07:09 PM	#1701
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Next step is 600mA per side then 2A, for enough perceivable niceness. But 200-250mA is the main chunk. Then up it goes diminishing returns. P.S. Post in 1024x748 links from now on (don't forget to kill the .th in the link else its thumbnails), the server takes refresh to auto resize, and big photos hinder browsing for people on laptops. I am gonna fix the above pics.

11th July 2010, 07:13 PM	#1703
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Hey, you can have your buffer, and the feeling (plus electricity bill) of running an F5 with one move!

11th July 2010, 07:17 PM	#1704
wushuliu diyAudio Member Join Date: May 2008 Location: Los Angeles	How do I check Vout w/ my DMM? Forgot about that part...

11th July 2010, 07:22 PM	#1705
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	You mean the reg's Vout? You can touch the 3rd pin of the Mosfets nearer to the relay with one probe, the other probe earthed. Or the left most pin of the left audio 2SK then the right most pin of its mate.

11th July 2010, 07:32 PM	#1707
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Just big size sinks. Under 1C/W per pair. You check voltage across Rset and you divide by Rset's value. If it gives 0.6A, then that is what you got.