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joeatari

A8 Custom Power Supply?

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When considering all the power bricks needed when powering an A8 computer, drives, printers etc. I'm wondering if anyone ever built (or considered building) a custom unified power supply?

 

My idea is to build one device that would power the computer and multiple floppy drives (maybe other devices) without all the many power bricks. I'm developing a crazy amount of power bricks on my floor!

 

Just curious what all the BBS veterans, etc. will say.

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I'm thinking about the same, or one DC and one AC supply. But the there's something like ground loop which has to be taken under consideration.

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I tried.... Bad things happen when you try to power 2 1050's from 1 9VAC brick with a splitter. Ground loop results in things like if one drive is switched on, the other drive will switch on as well, even if it is switched off. Its powering the other drive via ground loop through the SIO cable, which can burn out the wire in the cable...

 

Maybe the only 'good' way to do it is to modify all the AC equipment (ie disk drives) to run directly from DC... but I am no electrical expert..

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I've used old PC power supplies before. +5 for XL/XE and +12 for Indus, etc. You have to be careful though. Fuse each cable. The 9VAC devices are more of a problem although you could bypass the internal power supply in some of them and run them on +12v and +5v. Good USB chargers are pretty good for running a single computer....and a lot more compact than any of the Atari bricks.

Edited by JR>

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I tried.... Bad things happen when you try to power 2 1050's from 1 9VAC brick with a splitter. Ground loop results in things like if one drive is switched on, the other drive will switch on as well, even if it is switched off. Its powering the other drive via ground loop through the SIO cable, which can burn out the wire in the cable...

 

Maybe the only 'good' way to do it is to modify all the AC equipment (ie disk drives) to run directly from DC... but I am no electrical expert..

AC/DC differences alone won't make the difference here. If it's possible to have multiple devices connected individually with their own PSUs and have no ill-effects, it will be possible to power them from a single PSU. It might need some additional consideration, like separately switched outputs, but it will be possible with a small amount of work. Worst case scenario, an AC supply with multiple isolated outputs is pretty trivial to build.

 

I've used old PC power supplies before. +5 for XL/XE and +12 for Indus, etc. You have to be careful though. Fuse each cable. The 9VAC devices are more of a problem although you could bypass the internal power supply in some of them and run them on +12v and +5v. Good USB chargers are pretty good for running a single computer....and a lot more compact than any of the Atari bricks.

 

Yeah, I'm using a couple of official raspberry Pi power supplies for my Atari 800XLs, Working great!

 

PC PSUs are massive overkill for 8-bit stuff. Especially newer ATX PSUs, which might be dangerous to use with such low loads as they're built to expect a minimum load of dozens of watts. There are plenty of cheap industrial PSU modules by the likes of Artesyn, Mean Well etc. that would be better suited to lower loads, as well as being smaller.

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The safest and best bet you could make would be on a multi-tap transformer that offers several 9V AC outputs. I don’t think you could need to worry as much about ground loops and connecting various floating 9V AC sources together. Such a wonder may impossible to find.

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The Atari 9VAC bricks are pretty darn reliable. Just plug them all into a surge protector with a single switch. :P

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The safest and best bet you could make would be on a multi-tap transformer that offers several 9V AC outputs. I don’t think you could need to worry as much about ground loops and connecting various floating 9V AC sources together. Such a wonder may impossible to find.

Yep... But if you're building a custom PSU into an enclosure anyway, why not just fit as many discrete transformers as you like? Twin secondary 9V transformers are available off the shelf (for example, 2x9V 1.5A secondaries), so for 4 isolated outputs you only need 2 transformers. Add a Mean Well module (for example, 5V 4A & 12V 2A), and there you go - high quality 5V and 12V DC outputs, and multiple, isolated 9V outputs.

Edited by Daedalus2097
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Yep... But if you're building a custom PSU into an enclosure anyway, why not just fit as many discrete transformers as you like? Twin secondary 9V transformers are available off the shelf (for example, 2x9V 1.5A secondaries), so for 4 isolated outputs you only need 2 transformers. Add a Mean Well module (for example, 5V 4A & 12V 2A), and there you go - high quality 5V and 12V DC outputs, and multiple, isolated 9V outputs.

 

Are there heat concerns or other considerations if I was going to put 4 or 5 of these in one box?

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Are there heat concerns or other considerations if I was going to put 4 or 5 of these in one box?

Not especially, no. I would have the box ventilated as any PSU of a similar power (add the various power ratings together to get an overall figure), but those transformers themselves don't generate a lot of heat unless they're being pushed hard. I would keep all the outputs in phase, just in case some of them end up connected in parallel, but I expect that's not generally possible.

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This got me thinking again about one box power supply solution for multiple AC and DC devices. My idea is to use a metal enclosure, similar to Nu-Brick 64 Power Supply, and fit it with one or two dual 9V transformers (for two or four separate AC outputs) and one 5V DC power supply. I want it to be a modular PS with detachable power cords. This would eliminate even further unnecessary cable clutter, you would use only cables for the devices you want to power at the given time. It would also allow for a custom length of those cords and give you more freedom of what plugs you want to use (for example 2.1x5.5 or 2.5x5.5 barrel).

 

I have a problem finding a suitable connector on the power supply side. I want something that has 4 pins and has a threaded nut for better mechanical stability. 4 pins would allow me to have the same 5V DC connected to all outputs (for example pins 1 and 2), you could connect a DC device to any of the outputs. Pins 3 and 4 would be connected to 9v AC transformer, each output to a separate winding. Right now I'm considering M12 connector https://nianyeong.en.taiwantrade.com/product/wp-m12-f-4pin-d-coded-rear-lock-solder-type-lock-pg9-1786727.htmlbut they can get expensive. Does anyone have any other recommendations?

 

Single transformer version would have 2 AC outputs (shared with 5V DC) and 1 DC only, two transformer version would have 4 AC and 1 DC. How about adding one USB-A socket for additional 5V DC output (for SDrive Max)?

 

I want to make it user proof if I will ever want to sell it.

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I've been thinking along these same ines. I was thining of seeing if I could build it into a wide flat case, similar to those under monitor switch boxes we all used to have.

 

post-50483-0-84233100-1557870188_thumb.jpg

 

It could even have push buttons on the front to turn each thing on and off. Then, it could sit under your monitor and have one power cord going in and have outlets for 110 (or 220 depending on where you live) and then separately-keyed outputs for AC vs DC.

 

Create a few diferent cords with color-coding and clear marking, (Red plug with AC on the side, white plug with DC on the side, maybe?)

 

So, front has multile light-up push buttons. One for master, and one each for the 110/220 outlets and AC and DC outlets on the back.

The back just has cord in (maybe a master power switch and circuit-breaker) and then all the outlets.

 

I'm sure it wouldn't cost more than $100 to biuld one. :P

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For a modular PSU, you could use something similar to PC modular supplies - a set of Molex Mini-fit Jr connectors flush mounted on the front (clicky for example). These are cheaper than heavy duty threaded DINs, and have locking lugs to hold them secure, though they need to be board mounted so a little creative bracketing might be needed inside the case.

 

If I was going to do it, I wouldn't use one of the AC supplies for the 5V rail, since that could load it down quite a bit. I'd fit a separate mains-powered module that can also supply 12V (and maybe -12V too for Amiga use). I like the idea of having a standard connector for everything - maybe a 6-pin Molex - and only populate the pins needed for the particular supply you're using.

 

Including a couple of USB sockets is never a bad idea - so many things can use them.

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Molex would be the easiest choice, but it would look bad on the power supply used outside of the case. You would end up with exposed wires.

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