I've read that kapton & mica are the best insulation between device and heatsink. Tried to find the link, but was unlucky.
it's vice-versa actually
I need:
1. only the buffer
2. buffer + attenuator
the scheme shows both combinations with different colors marked. It would work in that way, though I'm not sure if that is the correct way of wiring
Don't know, you should look up their thermal resistance. If its below 1C/W they will be better than Silpads. Best is Keratherm Red if there was a difficult situation, but we have allowances here still.
If you are only running Shunt Reg at <~500mA you should be OK. Above that and your MOS-FETs are going to get VERY hot. Mine run nice and cool at 300mA, above that they start to cook.
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it's vice-versa actually
I need:
1. only the buffer
2. buffer + attenuator
Then you should use a switch shorting the attenuator or not.
I m running it at 1,2A and the temperature after 2 hours was about 50C on the case of the fets.
And that was with just the plate and the heatsinks just left on top of it. Not screwed on it, no thermal paste and no bottom heatsinks.
It s the aluminum plate that makes a significant difference.
I just hope the extra measures will be enough to compensate for closing the box
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More work today... Took me more than I expected... that damn thermal paste is all over the place
The chassis is glued together and finished with 120 grit sandpaper (It feels way smoother than it sounds...). I also put a layer of oil/wax and the wood got a nice dark color. The damn photo again is not doing it justice. I plan to do an additional layer tomorrow and after it dries I will put everything together.
You can also see the side vents and the spikes. I intent to make some smaller plates for them.
The heatsinks were properly screwed in place along with the Caddocks that are now below the pcb screwed to the plate themselves.
I also removed all wiring to replace it with pure silver and I added a white led which will show on the front panel.
The chassis is glued together and finished with 120 grit sandpaper (It feels way smoother than it sounds...). I also put a layer of oil/wax and the wood got a nice dark color. The damn photo again is not doing it justice. I plan to do an additional layer tomorrow and after it dries I will put everything together.
You can also see the side vents and the spikes. I intent to make some smaller plates for them.
The heatsinks were properly screwed in place along with the Caddocks that are now below the pcb screwed to the plate themselves.
I also removed all wiring to replace it with pure silver and I added a white led which will show on the front panel.
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Depends on the eyes !
Sorry I didn t build one more aluminum faceplate with heatsink sides
found some info in the net. It's 0.71 1 W/(m.K) for Mica and 0.6 for Kapton or even 0.12, though not sure if these are the right values for my tape...
thanks!
I have few pics of mine as well. I've run it for half of an hour with 3R css resistors. What could I say, it was about 60c on this tiny toroid (just confirmed what Andrew said dozen of pages ago), 80c on CSS Rs, 75c on mosfets, 60c on MUR860s, 55c on the sinks. I'll get some M2 bolts to attach mosfets properly on this week and continue with preliminary burnings tests
Last pic shows the layout, please let me know if it's decent enough?! toroid will be replaced with something <80mm width & <55mm height (probably should be some custom narrow 80VA or 65VA r-core transformer).
Yet another thing to clarify
As my goal is >=1A (I need >65VA transformer), would it be good to add additional solid 10mm aluminum plates to the heatsinks (as on pic 2) or perhaps to add a solid 10x160x250mm plate to the bottom? What I want is to win some several hundreds mA more to burn it even harder dimkasta
very nice chassis!
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After you will have the Mosfets properly bolted on sinks and final CCS current of choice, we will know the temperatures on sinks and Mosfet cases you will measure. From there we will be able to judge if they will be safe conditions in the long run or you will need to upgrade thermals either for pads or for extra metal.
thanks! is it safe to keep them above 60c? Anyway I was planning to attach them to the chassis.
it's 2.02 &1.85vdc with 2 x 6R per rail. So it's >600mA now. Not sure how much more could I get from the trafo as it's already on the edge to my understanding
I'll assemble the bottom lid and heatsinks and make the proper measurements. Will see then how far could I go.