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Old 28th June 2010, 10:15 PM   #561
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That is a very clever design, and I've had my eye on it. But I don't use vinyl any more. However, design features could be useful as a front end of something.

Andy
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Old 29th June 2010, 01:34 PM   #562
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Quote:
Originally Posted by zigzagflux View Post
I've used Wakefield 637-20ABP on multiple designs, including 300B heating with very good, cool results. These can handle 5W dissipation under chassis with some breathing holes above for airflow. PCB mounting is very convenient and compact. Cheap, too.

They also make a 63mm high version, but it's not typically in stock. I also use a skinnier version for TO-220 rectifier and power resistor mounting.

My preference is to stay off the direct-to-chassis mounting of semi's, but to each his own.
Thanks Kurt, that's useful.

The Wakefield Heatsink version is available from Mouser.

Also available in Europe, the Avid Thermally SW50 (8.8K/W) and SW63(6K/W) appear to be mechanically compatible, with a PCB footprint of 12.5mm x 34.5mm, with 2.5mm (.098") pins on 25.4mm (1") centres.

The drawing for the 63mm high version is here:

Standard Board Level Heat Sinks

This design has good power handling, easy PCB integration, low price, wide availability - I better adopt it for the board design!

Does the 50mm or 63mm height give anyone a problem?
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Old 29th June 2010, 01:55 PM   #563
barossi is offline barossi  Germany
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Hi Rod,
for my #26;i am using Caddock MP930 - 10 Ohm on a 2,2K/W heatsink:

Click the image to open in full size.

This is o.k., i would not choose a smaller heatsink :-)

KR Hauke
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Old 29th June 2010, 02:48 PM   #564
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I use 2U rack parts for my chassis, so my chassis height is 88mm. I think visually speaking the best solution for serious heatsinks is the time honoured practice of bolting them on the back plate. They're out of the way and this looks satisfying to me - you can use a fancy front, wood sides etc. I tend to put the connectors and knobs on the top plate since they're easier to plug in and out and you get the whole circuit on one plate.

So for me, it would be something like this, with 75mm height. It comes in various widths.

FISCHER ELEKTRONIK|SK 47/75 SA|HEAT SINK, 75MM, 0.45 - 1.05C | Farnell United Kingdom

Andy
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Old 29th June 2010, 03:04 PM   #565
barossi is offline barossi  Germany
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Hi Andy,

very good idea!
I will try to use the Caddock MP9100 10 Ohm:

http://www.caddock.com/Online_catalo...it/AEN0102.pdf

And a bigger <1 K/W heatsink

KR Hauke
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Old 29th June 2010, 03:07 PM   #566
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Thanks Andy. At 1K/W there will be no question about your semis running cool enough!

This rear-mount solution will work really well for high powered filaments, too - if you were thinking about a GM70 amp.

I'll keep in mind the hole spacing for this mounting style.
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Old 29th June 2010, 03:23 PM   #567
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http://uk.farnell.com/fischer-elektr...55?Ntt=4621955

Cheaper version. Actually my 75mm "height" which is the height of the back plate, is listed as Depth. Height is how far it projects back from the rear wall when mounted vertically on it, as it should be.

Andy

Last edited by andyjevans; 29th June 2010 at 03:27 PM.
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Old 7th July 2010, 10:35 PM   #568
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Just an update on the 10y in filament bias. I got some chokes - 280mH at 2.7A. I'm currently listening to a Thurlby bench supply going through these smoothing chokes into the 10Y.

Sound is exceptionally clear - in complex passages you can hear the discrete sounds of instruments more clearly. That's the predominant effect.

The chokes are moderately big beasts. Will have to work out where to put everything on the chassis for a more definitive build.

I know this is a 26 thread, but all this design would work for the 26 if you substituted a LL1660/5mA for the Hammond 126c I'm using. Hammond do suitable filament chokes as well.

I'm really enjoying all this!

Andy
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Old 8th July 2010, 03:27 PM   #569
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Tried to lay out the design with the PCB-mounted heatsinks AND keep it compatible with bigger chassis mounted types. This did not work out, and since some bigger filaments need bigger sinks, I've stuck to those, and left out the PCB versions.

The Board is ready to go out...

Here's the dimensions and hole positions - how do these work out on your chassis??
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Old 8th July 2010, 04:01 PM   #570
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Looks good to me Rod
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