Salas hotrodded blue DCB1 build - Page 148 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th November 2011, 09:46 AM   #1471
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Igor,
Salas has done a dissipation calculation for a 150mm tall heatsink.
Your heatsink is a lot smaller. maybe 1.9C/W @ deltaT=70Cdegrees.
Your transformer rated at 50VA 15Vac is effectively rated @ 3.3Aac.
This allows 600mAdc to use just 37% of full rating. It will run cool.

Expect about 22Vdc to 23Vdc at the input to the CCS when set to 600mAdc.

The worst case power dissipation (output shorted) is 0.6 * 22 * 1.06 = ~14W
DeltaT = ~14 * 1.9 * 1.3 = ~35Cdegrees.
Ts ~ 40+35 = ~75degC.
Tc ~ 75+ 1*14 = ~90degC.
De-rate a 120W 150degC device for Tc@90degC and you get [150-90] / [150-25] * 120 = ~58W.
Your worst case dissipation of 14W shows the device can survive due it's de-rated power capability being very much greater (@58W)

You will need to check the actual DC input voltage at the CCS to double check the actual dissipations. Sum the CCS and Shunt dissipations and apply that power @ nominal mains voltage to determine deltaT for the sink during normal operation. It will be very hot, so internal location is probably best. The rest of the circuit will be exposed to all this internal temperature.
__________________
regards Andrew T.

Last edited by AndrewT; 19th November 2011 at 09:49 AM.
  Reply With Quote
Old 19th November 2011, 12:38 PM   #1472
diyAudio Member
 
Join Date: Jul 2004
Location: North Carolina
Andrew,

Thank you for the thorough response including calculations. It is very easy to understand when the measurements are there and some objectivity is thrown in .

I will also include this link, which was a good descriptor for me, to attend to these heatsink calculations, as they come up often with solid state builds.

Best,
Anand.
  Reply With Quote
Old 19th November 2011, 04:18 PM   #1473
diyAudio Member
 
Join Date: Dec 2008
Location: Ljubljana, Slovenia
Andrew, thank you for calculation.

I messed up things a little. I have 10R resistors and thought those are for 600mA but this morning I went through this thread and found out that 10R is for 200mA hot-rod.
In this case, those heatsinks would be suitable if I'm not mistaken?

Once again, thank you for calculation.
  Reply With Quote
Old 20th November 2011, 05:47 AM   #1474
cersepn is offline cersepn  United States
diyAudio Member
 
Join Date: Feb 2010
Spent a couple of hours with the dcb1 yesterday and everything was good. But today i tried playing some music again and turns out one of the channels died...again. Only this time i didn't unplug any live rca and during yesterday's session there wasn't any loud boom or weird noises like that.

I measured the offset and the absolute values are good, but then i realized something weird - the faulty channel's offset is negative. Maybe it was negative all this while and i didn't realize it. Could that have been the problem?
  Reply With Quote
Old 20th November 2011, 07:20 AM   #1475
diyAudio Member
 
Join Date: Oct 2009
Quote:
Originally Posted by AndrewT View Post
Your transformer rated at 50VA 15Vac is effectively rated @ 3.3Aac. This allows 600mAdc to use just 37% of full rating. It will run cool.
Andrew, your math assumes a single secondary.
A 50VA Transformer with 15Vac + 15Vac will effective be rated @ 1.6Aac.
It will run warm.
  Reply With Quote
Old 20th November 2011, 09:47 AM   #1476
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I am glad someone is awake.
It never dawned on me that Igor could have dual secondary transformer but state 15Vac as the rated output.

If John is correct then the transformer will be run @ ~ double that 37% for the whole transformer. The one loaded winding will be run at ~74% of maximum continuous rating.
Solutions:
a.) reduce the CCS current
b.) parallel the 15Vac windings
c.) Accept that one secondary runs a bit warm and check the surface temperature of the transformer once up and running.
__________________
regards Andrew T.
  Reply With Quote
Old 23rd November 2011, 09:28 PM   #1477
Nick77 is offline Nick77  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Austin Tx
Is this the prettist Christmas Tree you ever did see?
Measured 9.7 and 9.8, waiting for more parts on Friday. Cant wait to listen.

Thanks all..........



Click the image to open in full size.
  Reply With Quote
Old 23rd November 2011, 10:09 PM   #1478
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
  Reply With Quote
Old 24th November 2011, 09:15 AM   #1479
diyAudio Member
 
Join Date: Oct 2009
Quote:
Originally Posted by Nick77 View Post
Is this the prettist Christmas Tree you ever did see?
Measured 9.7 and 9.8, waiting for more parts on Friday. Cant wait to listen.

Thanks all..........
Nice job done Nick,
You have some nice components on that board

Just make sure it’s not on for long without adequate sinking.
  Reply With Quote
Old 24th November 2011, 09:22 AM   #1480
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
John,
Did you ever finish your balanced b1?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
dcb1 buffer with shunt reg. merlin2069er Swap Meet 0 3rd August 2010 05:25 PM
F2 and DCB1 parts selection - please advice! DQ Pass Labs 6 25th November 2009 03:20 PM
Y B Blue - how blue LED improves the CD playback Peter Daniel Digital Source 176 25th September 2003 07:40 AM


New To Site? Need Help?

All times are GMT. The time now is 06:17 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2