aleph 3 bias and heating problem - Page 2

panos29 · 4th December 2001, 09:37 PM

o.k, message received well and clear :-)
How can i post an image of my amp? is this possible over here?

cp642 · 4th December 2001, 09:50 PM

Panos, check the link below, check out Adding Images
http://www.diyaudio.com/forums/index.php?action=bbcode

hifi · 4th December 2001, 10:18 PM

this might not be my place but i believe NP have ansvered that question a number of times and the answer have always been 55c for the mosfets. (ie heatsinks the mosfets will run hotter)

btw u can use this formula

Temp = Peffekt(lamdacase + lamdajunction + lamda heatsinktoair)

and se the different temps the junction temp shouldent go over 100c and the limit for the mosfets is 150c then they die....a crude and violent death...or something ;-)

there is a older thread where this is better explained!

/micke

jduncan · 4th December 2001, 11:06 PM

you have to be very careful in that last formula though to understand the difference between one, say, 200W point source of heat on a 20" length of heatsink and 10 20W heat sources spread out with 2" spacing on the 20" length of heatsink. These yield very different results so make sure you are actually calculating the correct data here.

Also make sure that you calculate power dissipation in each source (mosfet) correctly.

hifi · 5th December 2001, 01:35 AM

yes!....i concur...i was only showing the basic formula to make a reference to the earlier thread...

/mike

panos29 · 5th December 2001, 04:48 PM

Following the link bellow u can see 3 pics of my alepph 3 clone, if anybody needs pcb i can also sent copy pics of it too.
Thanks again to all who answered or red my posts.
Panos

http://briefcase.yahoo.com/bc/panos2...c=bc%26.view=t

jduncan · 5th December 2001, 05:58 PM

the link didn't work for me

cp642 · 5th December 2001, 06:16 PM

yeah...me too

panos29 · 5th December 2001, 06:19 PM

I hate that when it happens! it works fine to me and ! really cannot explain why! Anyway I just posted this to the gallery at passlabs too.
My appologies to all of u to whom the link is not working.

Panos

panos29 · 5th December 2001, 06:23 PM

Let me try once more

http://briefcase.yahoo.com/bc/panos2...c=bc%26.view=t

5th December 2001, 04:48 PM	#16
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	Some pics of my amp for everyone Following the link bellow u can see 3 pics of my alepph 3 clone, if anybody needs pcb i can also sent copy pics of it too. Thanks again to all who answered or red my posts. Panos http://briefcase.yahoo.com/bc/panos2...c=bc%26.view=t

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4th December 2001, 09:37 PM	#11
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	o.k, message received well and clear :-) How can i post an image of my amp? is this possible over here?

4th December 2001, 09:50 PM	#12
cp642 diyAudio Member Join Date: Aug 2001	Panos, check the link below, check out Adding Images http://www.diyaudio.com/forums/index.php?action=bbcode

4th December 2001, 10:18 PM	#13
hifi diyAudio Member Join Date: Mar 2001 Location: sweden	this might not be my place but i believe NP have ansvered that question a number of times and the answer have always been 55c for the mosfets. (ie heatsinks the mosfets will run hotter) btw u can use this formula Temp = Peffekt(lamdacase + lamdajunction + lamda heatsinktoair) and se the different temps the junction temp shouldent go over 100c and the limit for the mosfets is 150c then they die....a crude and violent death...or something ;-) there is a older thread where this is better explained! /micke

4th December 2001, 11:06 PM	#14
jduncan diyAudio Member Join Date: Nov 2001 Location: Boston, MA, USA	you have to be very careful in that last formula though to understand the difference between one, say, 200W point source of heat on a 20" length of heatsink and 10 20W heat sources spread out with 2" spacing on the 20" length of heatsink. These yield very different results so make sure you are actually calculating the correct data here. Also make sure that you calculate power dissipation in each source (mosfet) correctly.

5th December 2001, 01:35 AM	#15
hifi diyAudio Member Join Date: Mar 2001 Location: sweden	yes!....i concur...i was only showing the basic formula to make a reference to the earlier thread... /mike

5th December 2001, 05:58 PM	#17
jduncan diyAudio Member Join Date: Nov 2001 Location: Boston, MA, USA	the link didn't work for me

5th December 2001, 06:16 PM	#18
cp642 diyAudio Member Join Date: Aug 2001	yeah...me too

5th December 2001, 06:19 PM	#19
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	I hate that when it happens! it works fine to me and ! really cannot explain why! Anyway I just posted this to the gallery at passlabs too. My appologies to all of u to whom the link is not working. Panos

5th December 2001, 06:23 PM	#20
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	Let me try once more http://briefcase.yahoo.com/bc/panos2...c=bc%26.view=t