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my_ref revC group buy (Mauro Penasa LM3886 design)

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marc brown

marc brown

Member
Joined 2007
AndrewT said:
The buffer belongs at the source not at the receiver.

It is normal to specify a transformer for a regulated supply where
Vac= reg Vdc, i.e for 18Vdc use an 18Vac transformer. It would do no harm to use a 20Vac or 21Vac transformer.

A 3VA 30Vac transformer has an AC output current maximum of 100mA. It will run at it's maximum temperature if you take this much out in continuous duty.

When you use a capacitor input filter the output from the filter is almost exactly half the AC rating of the transformer.

I suggest that the transformer run at <=50% of maximum rating for continuous duty.
So the 3VA 100mA transformer should have a maximum continuous DC current of <=25mA.
Is 3VA big enough?
Click to expand...


So, what size transformer should I be looking for? Would something like this 12+12V 25VA toroid from Antek be ok? auction link
 
schro20

schro20

Member
Joined 2008
multires.caltech.edu/
kitting update

Just wanted to give everyone a quick update.

At this point all but 3 people are paid up (and those are just some technical snags that are being addressed). So we are good on the income side. On the expense side we have just about everything in. Today a big box from Digikey came. Yesterday was Mouser day. I am waiting on two more packages with components. One being another set of caps and the other being another big shipment from OnlineComponents. The latter is only expected to arrive next week because they are collecting individual parts from different warehouses.

I am labeling resistors while watching TV. Made a little gadget to do 30 at a time. I might try for the championships next year! :)

Uriah is putting together a READ ME for the package.

Anyway, things are moving along. I hope to have all the labeling and such done this weekend and then it's basically just holding our breath until the last components are here.

I'll post some pictures to wet your appetites this weekend.

peter
 
troystg

troystg

Member
Joined 2004
"I am labeling resistors while watching TV. Made a little gadget to do 30 at a time. I might try for the championships next year! "

After two different component kits GB's for the Krell KSA-50 clone (Jan's and Al's) I feel your pain and don't envy you at ALL.

Thank you so much for doing it again.

Big thanks to Mauro for the design, and Twisted Pair for allowing the second GB.
 
mightym

mightym

Member
Joined 2008
Since I ordered in on the Traffo GB, I'm now planning Mono Bloc's with my kit.

My question is just how much heatsinking will be required?

On Apex Jr.'s site front page, he shows a gold finished heatsink aprox 6x9x2

If I ordered one and cut it in two to create two aprox 6x4.5x2 would they work for the mono bloc's

The balance of the cases will be wood.

I hope this isn't too dumb a question...

John
 
schro20

schro20

Member
Joined 2008
multires.caltech.edu/
resistance is futile!

Just a quick update. All the resistors (4000 of them...) are labeled and neatly packaged into individual packs for the kit. I think I am done with the worst part. Leaves mostly the small ceramic caps in need of labeling. I figure I will leave anything unlabeled which is obvious and easy to identify.

Photos at http://picasaweb.google.com/schro20/RevCKitting

Big thanks for Cici for helping!

Peter
 
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