I have one project I'd like to do someday: I have the boards and transformer from a Sumo Andromeda II (v3), that a fellow forum member gave up on. He used the case for some other project, though. I see one maybe suitable case on eBay, but it's over $400 after shipping. Wondering what more affordable ideas there are for 19" cases with heat sink for 200WPC of class AB power.
One idea I had was to order some decent looking heatsink pieces from Ali Express. They're reasonable height and thickness, but way too short. I could weld four or five of them together, though (TIG). Aluminum plate pieces and other hardware is not too expensive from McMaster. But that leaves the question of vents for the top and bottom. Are there any more reasonable options for decent cases?
One idea I had was to order some decent looking heatsink pieces from Ali Express. They're reasonable height and thickness, but way too short. I could weld four or five of them together, though (TIG). Aluminum plate pieces and other hardware is not too expensive from McMaster. But that leaves the question of vents for the top and bottom. Are there any more reasonable options for decent cases?
Look for a cheap blown-up audio amp, like a Hafler, etc. Local would be least, since no shipping.
Yes, I've seen these. Nice, and convenient, but probably 10X the price of welding together some Aliexpress ones, and I still don't know what to do about the top and bottom of the case.
You can get away with very small heatsinks in most AB amps, there’s aluminum everywhere find some scrap and roll…a plate with 4 cpu heatsinks attached? 20 aluminum cans flattened fanned and bolted? (Think twister but thicker, careful they are usually coated) broken AVR usually have enough to use, many incorporate fans might be a problem…stacked and bolted aluminum bar and plate is easy and cheap. Scrap led heatsinks etc…2 or 3 sizes of aluminum c-channel bolted together like Russian nesting dolls?
In no particular order.
* you don´t need to TIG weld them, which in any case will NOT guarantee flatness at all, just join them together by bolting to a rectangular aluminum flat plate, full size and of course add a little thermalgrease between them.
Then you have a nice flat surface to mount your power transistors.
That alone will save $$$$$
* that frees you to use any commercial rack sized chassis, where you can pick a lowish cost one.
* I see heatsinks era external, chassis sides, so no need for vents for them.
If you want to vent chassis inside, which is fine, multiple drill top and bottom panels with a proper drill or make multiple coin sized holes with a stepped drill which to boot leaves clean edges behind or cut rectangular vents with a nibbler, there´s many ways to skin a cat.
* that working with home shop tools; maybe you have access to a friendly metal shop which can punch a few proper sized holes and charge little or perhaps a sixpack or two.
I did that at the beginning, always "forgetting" a couple good wine bottles on the desktop, later recognized that the MAIN bottleneck for makers is not the Electronics part (that one is "easy") but the "mechanical" one, so I always invested in machinery, custom dies, etc.
Recovered every single Dollar MULTIPLE times and that allows me to quote "impossible" prices, plus offering short times and peace of mind.
IF needed I can make a custom rack cabinet in about 2 hours, go figure, and paint and silkscreen it in another 2, like on the Mastercard ad: "there´s some things money can´t pay" 😉 .
Those are not that pricy.
In my opinion they are reasonable.
And it's one item you certainly don't want to compromise on.
That "Ali" site is questionable stuff.
There's another thing re shipping over things from China that have had me wondering, of some odd reason as soon as one pile up items to the shopping list on Ali such as heavy metal stuff like bigger alu cases, heatsinks, transformers etc., the shipping price seems to go up not linearly with the weight but rather exponentially, of course with smaller items one can make several single orders to get the lowest shipping price, which is nuts, but if one item weighs more than a kilogram or two or wherever that magic weight threshold sits where the shipping price suddenly jumps up considerably, then it doesn't work just like hey let's cut that heavy transformer in several pieces to get a low shipping price.
I was looking into buying a set of OPT cores in the past but the shipping price of $150 killed the anticipated project so no cigar for Xi, yet, but I have come across recently there are apparently some kind of helper agencies in China that can help with both buying and shipping, I think in my case with the cores is that the seller were inflexible as they use some premium delivery company that hikes up the shipping price a good bit, have to look into it again, or maybe not considering all the semiconductor and tube "crisis" hiking up those prices too.
I was looking into buying a set of OPT cores in the past but the shipping price of $150 killed the anticipated project so no cigar for Xi, yet, but I have come across recently there are apparently some kind of helper agencies in China that can help with both buying and shipping, I think in my case with the cores is that the seller were inflexible as they use some premium delivery company that hikes up the shipping price a good bit, have to look into it again, or maybe not considering all the semiconductor and tube "crisis" hiking up those prices too.