GroupdDIY 511 Racks: round 5.5 available

[sahib]

Time for an update.

Second batch of 100 is under production. Connectors are in stock.

The design of the mechanics of the psu is completed and I am building the final prototype this weekend and will be testing it. It is almost there.

Stay tuned.

 

[jsteiger]

What's your plan for the heat sink?  ;D  Got any pics?  8)

 

[Dubka]

Great news!
1 full kit please.
Martin

 

[sahib]

What's your plan for the heat sink?  ;D  Got any pics?   8)

You have the picture don't you? 

 

[jsteiger]

You have the picture don't you? 

Why yes I do!

Nothing like a big-ole heat sink!  ;D

 

[Echo North]

I want that.  ;D

Nice.

Mike

 

[Brolik]

me too! pleasepleaseplease!!!

 

[Dubka]

Ha!!

Kind of ridiculous AND cool at the same time.  Can't wait.. 

Plus this means I get to sell my API Lunchbox!

Anyone want to buy one?

Thought not...

 

[sahib]

If you meant the size of the heatsink it is not really ridiculous. You have no idea how hot it is down there. I expect the surface temperature on the L bracket to be around 45-50 degrees C under full load. Transformer will also run at around 55 degrees C under full load. This is normal by the way as Volker has already checked it with the manufacturer. However, I made the boss of the acetal mounting plate (white thingy under the transformer) to go under the transformer to create a gap so that it actually hangs over with bottom part of the winding exposed, releasing heat in the air.

 

[Dubka]

Oh yeah, I didn't mean it in a bad way at all.  It's just massive!

 

[sahib]

Sorry, I didn't get it. No probs. Whole aim is to run it as cool as possible within the budget. Obviosuly we can stick a big door stopper there and it won't go beyond 30 degrees but it is unnecessary and costly.

 

[Ptownkid]

That is one serious heat sink!!!

 

[dandeurloo]

amazing! 

 

[Denyle Guitars]

Why the L bracket? Is that just to keep the heatsink away from the pcb?

FWIW, I found a large 12x9 heatsink on ebay and quartered it on the bandsaw. My plan was to mount them on the sides of a 2u case.

 

[sahib]

The L bracket is there for ease of assembly and servicing.

The other option can be that you can have a single heatsink but the regulator pairs are seperated by the L bracket. In which case L bracket allows a good seperation between the regulator pairs so that when one pair is working harder and dissipating greater heat, it does not heat up the other regulators unnecessarily.

However, I chose to use seperate heatsinks with a view that both regulator pairs will work under full load. In terms of cost there is a little increase in labour but it is worth in the long run.

 

[sahib]

I have finished the heatsinks for the rectifiers and I am populating the pcb at the moment. I am going home just now and will continue tomorrow. 

 

[jsteiger]

I have finished the heatsinks for the rectifiers and I am populating the pcb at the moment. I am going home just now and will continue tomorrow. 

Oh My Cemal.  That is frickin' awesome!! I have been looking around for a stock heat sink but have been striking out for that bridge rectifier package. I am so impressed by what you have done here!! 

Best, Jeff

 

[sahib]

Just to keep you happy Jeff, just to keep you happy. 8)

 

[jsteiger]

Just to keep you happy Jeff, just to keep you happy. 8)

Thanks Cemal! But it's more about those rectifiers. If we keep those 4 hard working guys happy (and cooler)...I in turn I will be happy!

 

[jdbakker]

Cemal,

It's hard to tell from the picture alone, but isn't the thermal resistance of this combination dominated by the L-profile? This looks like a bit of a waste of a fine (and probably expensive) heatsink. If nothing else, it may be useful to replace the L-profile with a T-profile to improve the thermal coupling.

JDB.
[constructions like this one usually show a strong thermal gradient across the horizontal part of the L-profile, particularly since as shown the die of the regulators is almost at the edge of the profile]