FREDS HOT

[li_gangyi]

cool poem...but I'm still wondering why the FRed's wun work...got no problems with mine...and they dun run hot...

 

[jleaman]

The hum is now fixed. BUT the heat is not. They are currently sitting on a big heat sink and still get warm.. if Fred's are going to get this hot im not going to use them. It seems to me that they will need a bigger heat sink than the actual amplifier.

NONSENSE

 

[jleaman]

here is the schematic that peter daniel gave me to use...

 

[Kermit]

B1060’s? Is that MBR1060 diodes? 10Amp, 60Volts? What’s your transformer secondary? Could it be that you are running them at too high voltage? There really shouldn’t be any need for such a big sink. I recommend you try some mbr20200 if your mind is set on schottky rectifiers. Or since you already have 8 of them try using 4 for each secondary, reducing the voltage and current the diodes have to deal with.
Out of curiosity, the hum you had, was that from the speakers or from the transformer? When I replaced the standard bridge rectifiers in my amp with mur3060 and rc snubbers I experienced a huge improvement in transformer noise. With just the standard bridge I could hear the transformer humming from a few feet away, but with the mur3060’s I hardly hear any transformer hum, even with my ear right up against the transformer.

 

[tbla]

please - for your one sake - get some mur860, from onsemi.....🙂

 

[jleaman]

the main rails are 45 0 45 and the transformer never hums or gets warm.

It is fairly Quiet.

i dont have any money right now to get mur860's.. all my money just went into my new APPLE 17" POWER BOOK : O )

 

[Kermit]

Well, there’s your problem.. that’s waayy to much for those diodes. As a rule of thumb use a diode that has a PIV of at least twice the worst case peak AC voltage.

 

[Kermit]

Btw, onsemi has a very generous samples policy 😉

 

[grataku]

all my money just went into my new APPLE 17" POWER BOOK : O )

I think that's the real problem! 😉

 

[tbla]

ok, the one nearest by will send you some mur860........😉

 

[jleaman]

I really dont want to see this part of my post be ruened. BUT i have to say it..


apple is better than pc.


Now back to the Topic.

 

[li_gangyi]

Hey~!! You could get free MUR860s here...
www.on-semi.com
Fill up the registration from and search for the part...hit the samples buttong and checkout...
get 50...of those for free...

 

[jleaman]

when i click on yur link i get this


http://in.netster.com/Index.asp?Site=b24tc2VtaS5jb20=

and tons of popup's

 

[jleaman]

Ok here is another redo of the freds there on a bigger heat sink.

 

[usekgb]

when i click on yur link i get this


http://in.netster.com/Index.asp?Site=b24tc2VtaS5jb20=

and tons of popup's

It's actually this: ON-Semi

Cheers,
Zach

 

[jleaman]

GRR after filling in all that stupid information and hit submit it fails GRRRR

 

[li_gangyi]

ermz...sorry for the wrong link...but anyways...it works on mine...I mean the samples program...

 

[usekgb]

I just put my request in today. I got some MOSFET's while I was at it. Thanks for the tip on the samples.

Cheers,
Zach

 

[li_gangyi]

Yeah...the samples are a real help when u are kinda cash strapped...I managed to build an entire amp under SGD$50 with the samples program...

 

[TNT]

Well, there’s your problem.. that’s waayy to much for those diodes. As a rule of thumb use a diode that has a PIV of at least twice the worst case peak AC voltage.

Peak voltage where and how ?

Could You elaborate a little on this as I'm tryinmg to do some dimensioning of discrete rectifier diodes ?

Best Regards /