Future PSU designs

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exxos
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Re: Future PSU designs

Post by exxos » Mon May 14, 2018 7:54 pm

2 months gone so fast since last update!

So 2 boards pasted up, most parts on.. and now in the cooker!

p2.jpg
p2.jpg (98.21 KiB) Viewed 606 times
IMG_2647.JPG
IMG_2647.JPG (216.35 KiB) Viewed 602 times

To be continued...
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dhedberg
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Re: Future PSU designs

Post by dhedberg » Tue May 15, 2018 11:45 am

Sexy! Like the color of the PCB! :-)
Daniel, New Beat - http://newbeat.atari.org. Like demos? Have a look at our new Falcon030 demo MORE.

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Re: Future PSU designs

Post by exxos » Tue May 15, 2018 11:48 am

dhedberg wrote:
Tue May 15, 2018 11:45 am
Sexy! Like the color of the PCB! :-)
Prototype colour ;) Actually not sure what colour to make the finals yet..
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Future PSU designs

Post by exxos » Tue May 15, 2018 11:54 am

Some scopes on the output under dummy load..

5V loaded with 2.2R ( 2.27 Amps)
10mV ripple and noise (0.01 Volts) Probably about 5mV ripple alone.
5v______.png
5v______.png (3.79 KiB) Viewed 582 times

5V loaded with 1R (5 Amps)
6mV ripple & Noise ( 0.006 Volts)
5v2_____.png
5v2_____.png (3.84 KiB) Viewed 577 times


12V loaded with 10R (1.2 amps)
18mV ripple and noise (0.018 Volts) Probably about 10mV ripple alone.
12v_____.png
12v_____.png (4.05 KiB) Viewed 582 times

So I am pleased with that. Not bad at all considering this design doesn't have a ripple filter at all 8-) Results should be better with more uF on the lines, so good motherboard caps should help squash it down some more, not like its really needed though.

Next I need to do some tweaks to the PCB and get a new prototype done..

EDIT1:

On order.. more waiting I guess now...

310.jpg
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4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Steve
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Re: Future PSU designs

Post by Steve » Tue May 15, 2018 6:31 pm

I like Guss assmans idea of making the voltage selection user-solderable, to make sure mistakes aren't made on the user end.

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Re: Future PSU designs

Post by exxos » Tue May 15, 2018 7:07 pm

Steve wrote:
Tue May 15, 2018 6:31 pm
I like Guss assmans idea of making the voltage selection user-solderable, to make sure mistakes aren't made on the user end.
Problem is, people get confused easily over what wires to solder where as it is :roll: Though I probably will sell these without primaries connected as it saves me having to keep stocks up of 2 different versions then.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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guus.assmann
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Future PSU designs

Post by guus.assmann » Wed May 16, 2018 8:28 pm

Hello Exxos,

If I see it right, there's 3 primary windings needed. Or maybe it can be done with 2.
3 windings: 115V, 115V and 10V.
All series = 240V, 2 x 115V series for 230V, 2 x 115V parallel, obvious.
Or maybe you can get away with 2 windings of 120V.

Now if you have those windings made such that one end of all windings have only one color.
The other end of the 115 or 120V winding has 2 very contrasting colors (as bars) and the 10V winding has a different setup.
Why the contrast? A (large) percentage of men are color blind. :shock:
This way, I think it's hard to make a mistake..... and if you can go for 2 x 120V windings, the error chance is smaller still.

BR/
Guus

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Re: Future PSU designs

Post by exxos » Wed May 16, 2018 9:34 pm

The colours are wired into the transformer.. that's nothing I can change.. the colours are printed on the side on the transformer from factory for how to wire the voltages up, I will do a couple images on how to wire up anyway.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Future PSU designs

Post by exxos » Thu May 17, 2018 9:58 pm

I loaded 5V rail with about a 1R resistor, so the current draw was about 5.2amps.. The ST typically pulls about 2amps, so this is a somewhat unfair test.. But I wanted to see whether thermal hotspots were on the PCB.

The load resistor was certainly very hot..
IMG_2721.JPG
IMG_2721.JPG (65.68 KiB) Viewed 509 times

So onto the PCB..
IMG_2723.JPG
IMG_2723.JPG (65.09 KiB) Viewed 509 times
Of course the back of the chip will be the hottest , and actually the temperature was going down, I did not let the probe cool after testing the resistor. But again, this is not the final PCB as I will use thicker copper on the final so the heat dissipation will be a lot better in the final board. I have however added in a lot of via's to even out the thermal performance on the top and the bottom of the PCB. Also small holes will allow a bit of air ventilation should help keep things cooler.

So I am onto the next revision of the PCB.. Which will likely be more final version..
top.png
top.png (153.84 KiB) Viewed 509 times
I also realise one of the ceramic caps is actually getting rather hot as it is thermally coupled to the 5 V regulator. Oddly the demo board was built this way, but in any case, I have cut a slit around the capacitor to isolated thermally from the regulator and just coupled it to the gnd layer on the bottom with a few via's. So it is still electrically connected, but thermally it is a lot more isolated now. I did not like the idea of capacitor getting hot like that, though for the most part it is really unavoidable as the capacitors have to be close to the chips as possible. I have also ordered the proper IR thermal meter, so I can see if there is any hot spots on the PCB.

It will probably be a couple weeks before the previous revision arrives so I can test the other changes I made.. So this current revision PCB will likely not get produced a couple months yet. I will likely build up a few boards for sale as initial prototypes at a lower price, so I can recover some of the costs involved so far as it is starting to ramp up a fair bit :roll: so if anyone wants to get their hands on "pre-release" PSU at a lower cost than let me know..
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Future PSU designs

Post by exxos » Tue Jun 05, 2018 7:40 pm

Rev2 PSU boards arrived :) Now to find some time to build a couple for testing..

psurv2.jpg
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4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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