F5 Turbo Circuit Boards

[jacco vermeulen]

Originally Posted by 6L6

they only seem to go to about ~60mm tall.

1.65" wide heatsinks that mount diodes on both sides go up to 2.5" height.
e.g. Wakefield 657 or Ohmite F/R series, ~4.25 C/W natural convection at 25C above ambient.
And even then, trouble is to locate a vendor that still carries taller than 2 inches.

On the other hand, try finding a source for Wakefield 256 :
256,260 Heat Sinks Wakefield Engineering PDFs òåõíè÷åñêàÿ äîêóìåíòàöèÿ 256,260 Heat Sinks îïèñàíèå ñêà÷àòü 256,260_Heat_Sinks.pdf Wakefield Engineering PDFs datasheets datasheet data sheets 256,260 Heat Sinks Wakefield Engineering PDFs
(see pics of my Pumpkin build )

[Bksabath]

Originally Posted by koja

Where are all those people who were attending this thread back in Feb.?

If you are referring to me
I am still hear and watching
To me PSU board has far too many tracks crossing over to many bends and one to many layers.

I may get a chance to go balanced in the next week and after that I will start on proper (45 or more V rails) Turbo.
But that will have proper buss bar on output.....

Still supply board is going to be the same as one I posted early.

And it seems like outboard Rectifiers are much better option.

I am always willing to help if you need it and you can PM.

If you are not referring to me no big deal just Ignore this post

[Zen Mod]

I'm certainly ignoring it

[buzzforb]

So dodo bird has technical question about diode heat dissipation. Am i wrong in my thinking that a single diodes will see 15-20w max in most cases, and this only on extreme passages of music. Add multiple pairs and the likelihood decreases all the more, correct? How am I screwing up this time. I got TeaBag's V3 version almost done, but can't decide how to mount the diodes. It seems to me that mounting them to the main heatsink is just introducing them to unnecessary heat, but they can take it I guess. Just hoping for some of the audio savants to chime in here.

[Rush]

Originally Posted by buzzforb

So dodo bird has technical question about diode heat dissipation. Am i wrong in my thinking that a single diodes will see 15-20w max in most cases, and this only on extreme passages of music. Add multiple pairs and the likelihood decreases all the more, correct? How am I screwing up this time. I got TeaBag's V3 version almost done, but can't decide how to mount the diodes. It seems to me that mounting them to the main heatsink is just introducing them to unnecessary heat, but they can take it I guess. Just hoping for some of the audio savants to chime in here.

Did you say savants?
I'm no savant, but I decided to go head and mount the diodes on the same heatsink as the Mosfets. I don't need more complications, the main heat sink should stablize at some point and that is what you want, thermal stability.
I will place the MOSFETs near the bottom of the heatsink the diodes will naturally be inline above them. If this proves to be a problem, then I will punt the ball.
I have been out of town for two weeks with no opportunity to complete this project. This weekend I hope to have one channel warming up. The chassis is falling behind, so this one channel will be a mess on the workbench (floor in this case, as it exceeds my workbench space, remember the hoarder I am).
Rush

[nrg2009]

Ha ha, guess I'm a hoarder also... i can never build a work bench large enough to hold my project(s)...

[sippy]

I'm one of the 'fraidy cats' - I'll wait for others more knowledgeable / less fraidy than myself to see what's what.
I still follow with interest though

[JojoD818]

Originally Posted by UKToecutter

Power Supply

Hi UKT!

I really like this one, but can we get a rather larger heatsink in there for the diodes? I know pcb real estate is critical but I guess the tradeoff and piece of mind may compensate for that.

What do you think?



Regards,

Jojo

[AndrewT]

At lowish currents the forward voltage is likely to be between 400mVf and 700mVf.
The datasheet will confirm that Vf rises with current.
A current of ~15 to 20Apk will likely require >=1Vf to pass.
For a paralleled pair, that would be 30 to 40Apk to get to your estimate of 15 to 20W dissipation per diode.

[buzzforb]

Originally Posted by AndrewT

At lowish currents the forward voltage is likely to be between 400mVf and 700mVf.
The datasheet will confirm that Vf rises with current.
A current of ~15 to 20Apk will likely requires >=1Vf to pass.
For a paralleled pair, that would be 30 to 40Apk to get to your estimate of 15 to 20W dissipation per diode.

Exactly, Doesnt this mean that the heatinking reequired for the source diodes is really not that great, especially considering the use of mulitple pairs. How many times will an amp be pushing 40Apk into a load, unless it is a subwoofer?