A couple of things I’ve been working on in my spare time.

First up, a fully customised computer PSU with seriously tweaked electronics and a custom case.

I know, I know, construction hasn’t matched the drawings exactly.

The material is 4.5 mm acrylic, with a couple of bits and pieces of 10 mm.

Yes, that’s an XLR connector for the mains power input, along with a fuseholder.

(A computer PSU will only draw 2-3 A.)

The relay provides a switched 240 V output, eg. for water pump and 240 v fans, and also provides a very nice pair of indicator lights (the neons) – red for power applied but PSU in standby, and green for PSU running. It does look good.

The fan on the top (or bottom) is a 92 mm, there will be no fan on the back, just the vent holes. I would have gone for 120 mm, but I only have a 90 mm holesaw.

You might think that the mains line filter is overkill and not needed, but there is a very good reason for it which we’ll see down the track when you see the PCB.

I stuffed this one up, actually, the holes at the front are too big, so I’ll have to re build the outer acrylic box and put it all together again.

No, I’m just ripping the guts out of a PSU and whacking it into a custom case, which we’ll see later.

More to come later.

Also… something else.
A vapour compression refrigerator for a computer CPU.

Compressor is a Matsushita FN66Q11G, just a standard 1/4 HP fridge one scavenged from some hard rubbish fridge.


Now… an evaporator.

I realised that I had an unused cavity magnetron laying around… I’m the kind of guy that has these things laying around, and I thought, well, by rights, it’s essentially a solid cylinder of copper, with little cavities and vanes machined inside it. Maybe, it can be fashioned into a good evaporator.

This evaporator won’t deliver record performance – of course, a custom designed, properly milled evaporator will always deliver better cooling performance.

But this cost me nothing to make, and took about half an hour to have it mostly assembled. I know it seems a little bit ghetto, but it certainly will work – and should work more than adequately well, for a first venture into phase. It can always be replaced with a better performing evaporator in the future. Of course, there’s a flat copper plate brazed on to the bottom, that’s not shown in these pics.

It’s just a matter of removing the magnetron core from the magnetron case / heatsink after you’ve ripped it out of the oven, removing the magnets, cutting the ends off, putting a tube in one end, the flat plate on the other end, and brazing it all together.

Incidentally, immersion in vinegar works fantastically well for cleaning oxidation off copper, and cleaning the silver soldered joints, getting the flux off and stuff… it works even better than the conventional practice of using hydrochloric acid.

Incidentally… (again) it seems like such a waste to be working with macroscopic rods of silver metal… only to waste it on a bit of metallurgy, doesn’t it?
Go down the pages for pics of the evaporator block.

Now, I need to get a condenser from somewhere, and add a condenser and fan, then put the oil back in, lap the base off the evaporator, make up a mount for the evaporator, and put insulation on the suction line, and we should be ready to charge it.

I forgot to put the insulation on the suction line before brazing it together. :(

The capillary tube to the evaporator is kept entirely inside the suction like, as you can see.


240VAC distribution/switching/power supply board

The microcontroller and the low voltage stuff. Some provision to drive some fans, and control them, too.

Having fancy electronics to control the compressor is not essential, but it’s a nice touch, and it lets you build temperature metrology into the system nicely, too.

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