Future PSU designs

Repairs & upgrades.
Velociraptor
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Re: Future PSU designs

Post by Velociraptor » Mon Sep 09, 2019 9:01 pm

exxos wrote:
Mon Sep 09, 2019 8:57 pm
i'm still waiting for the transformers to come.. there are some 110V ones still in stock (assuming you are talking about the 230V ones ?) you can configure them to 230V anyway.
Is it much work for me to change the 110V over to 230V? If it isn't I'll buy one before the Exxos Curtain falls across Europe.

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Re: Future PSU designs

Post by exxos » Mon Sep 09, 2019 9:28 pm

Velociraptor wrote:
Mon Sep 09, 2019 9:01 pm
Is it much work for me to change the 110V over to 230V? If it isn't I'll buy one before the Exxos Curtain falls across Europe.
Nope.. just wire the same as 230v... the 2 transformer wires left over you just solder them together (purple and grey I think )

EDIT: yep...

exxosfalcpsu.jpg
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Velociraptor
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Re: Future PSU designs

Post by Velociraptor » Mon Sep 09, 2019 9:52 pm

Ok I'm a little confused by that. There's two wires, orange and blue - do I just solder them together?

As for your shop problems, are you sure you're working to the correct deadline? As far as I'm aware the FCA has confirmed an 18 month delay on SCA part of PSD2 which should mean you have 18 months to implement it.

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Re: Future PSU designs

Post by exxos » Mon Sep 09, 2019 10:01 pm

Velociraptor wrote:
Mon Sep 09, 2019 9:52 pm
Ok I'm a little confused by that. There's two wires, orange and blue - do I just solder them together?
Thats the mains in wires.. see viewtopic.php?f=9&t=1510
Velociraptor wrote:
Mon Sep 09, 2019 9:52 pm
As for your shop problems, are you sure you're working to the correct deadline? As far as I'm aware the FCA has confirmed an 18 month delay on SCA part of PSD2 which should mean you have 18 months to implement it.
I don't know of any delays, been to busy to look. Supposed to come into effect on the 14th friday. But my new store is getting to beta testing now anyway.
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Re: Future PSU designs

Post by Velociraptor » Mon Sep 09, 2019 10:23 pm

https://www.fca.org.uk/news/press-relea ... entication

You do need to do the work at some point, so at least you've got it done. However if you're still not satisfied with it then you don't need to close the store at least.

I don't understand what you mean about the power supply though. The link you provided means nothing to me either. I've looked over both of your posts and the post you linked to and it's completely baffling. Perhaps if I had the PSU in front of me it would make sense.

Edit : trying to puzzle it out it seems that 2 wires require to go to the power switch. That makes sense of course.

Are the pictures showing a PSU as well as some kind of mounting assembly that includes the power socket and switch? And the mounting assembly is not being changed?

https://www.exxoshost.co.uk/atari/last/ ... htm#PSUFIT

That link is helpful and I'm confident I can carry out all of the steps on it, and I'm crossing my fingers there's no roms beneath the PSU.

However I've still no idea at all what you mean about changing the 120 to work at 240.

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Re: Future PSU designs

Post by Velociraptor » Tue Sep 10, 2019 12:17 am

I'll leave it until I've moved house. I'd otherwise need to get it in the next day or two and be pushed for time.

I'm sure the ST will survive another month until I'm ready for it.

Good luck with getting the store working right.

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Re: Future PSU designs

Post by exxos » Tue Sep 10, 2019 11:41 am

Velociraptor wrote:
Mon Sep 09, 2019 10:23 pm
I don't understand what you mean about the power supply though. The link you provided means nothing to me either. I've looked over both of your posts and the post you linked to and it's completely baffling. Perhaps if I had the PSU in front of me it would make sense.
The 230V PSU's I supply with the grey & purple wires soldered together.. the 110V ones are not, so you just solder them yourself. The brown and blue wires go to the switch , that's it.
Velociraptor wrote:
Mon Sep 09, 2019 10:23 pm
Are the pictures showing a PSU as well as some kind of mounting assembly that includes the power socket and switch? And the mounting assembly is not being changed?
You just take the old PSU, remove the PCB and 2 wires to the switch, bolt on the new psu board, solder brown and blue to the switch, done!

Of course the 110V ones needs grey and purple wires soldering together to configure for 230V as well.
Velociraptor wrote:
Mon Sep 09, 2019 10:23 pm
https://www.exxoshost.co.uk/atari/last/ ... htm#PSUFIT

That link is helpful and I'm confident I can carry out all of the steps on it, and I'm crossing my fingers there's no roms beneath the PSU.
Those are for the old style PSU.. So there is no drilling holes etc on the new design, other than the 4 screws holding the pcb on (like the old one) that's all you have to do.
Velociraptor wrote:
Mon Sep 09, 2019 10:23 pm
However I've still no idea at all what you mean about changing the 120 to work at 240.
Have a look at this thread... viewtopic.php?f=9&t=1994

There are just dual primary transformers.. like in parallel for 110V, or series for 230V... this diagram shows a example of this..

027_02.gif
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Re: Future PSU designs

Post by exxos » Sun Sep 22, 2019 1:27 am

I keep trying to think up ways to make the PSUs cheaper. I've been thinking that on the STF type machines, 12 is only used on the rgb port. Its not needed otherwise, unless someone has a really old floppy drive which uses 12v. I half recall 12v may be used on something else in the falcon but can't remember ..

I was sure I saw some fully intergrated 5v to 12v STEPUP ICS but can't really find ones which do not need a inductor. If I need a chip and inductor I might as well leave the circuit as it is now.

Then I thought, if I just ran the 12v direct from the rectifier , likely from a 9vac transformer, then it would output about 12v anyway. It could still power floppy drives I think, just it wouldn't be regulated . a smaller transformer could be used, but I'm not sure they would be much cheaper than the one I'm using now.

I'm really thinking towards a PSU for the remake boards. There not much use in having 12v if nothing really uses it. There is no need for a 3amps regulated rail just to go to the rgb port.

I'm not suggesting this will become the norm, I will still produce the PSUs I do now. Just thinking of a "LC" type version as well. It would likely just be a transformer swap and a link wire for the 12 rail. So it wouldn't really create any extra work I think.

I suspect the end price could be about £10 cheaper. Not huge but if there is enough interest I may do a small batch...
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Re: Future PSU designs

Post by exxos » Mon Sep 23, 2019 12:08 pm

I've been looking at ways to generate the 12V. Though to use a smaller transformer, it means the voltage has to be sacrificed. Which means a ideal DC voltage of about 10-15V. generating 12V from 15V is what happens currently and its pushing it a bit. Though the 12V regulator can take a lot higher input voltage.

Problem is, under load , the DC voltage drops. So its possible the DC could be higher or lower than 12V. Which would need a buck/boost IC to basically convert 10-15V DC to 12V.. which is just silly. It ups costs to much.

I did consider using 2 rectifiers as the transformer is dual secondary, but again, its upping costs.

The only way which seems likely to work, is to use a 5V to 12V boost converter. The 5V IC having a constant output voltage makes easier work to step up to 12V. It will add more noise to the 5V rail, but this is a "LC" version so sacrifices have to be made. Though its not going to be to bad anyway. This will allow a transformer half the size to be used (cheaper) and with extra board space, I may be able to fit a voltage selector on it for 110V/230V.

Its just a matter of *if* there is a low cost step up voltage solution out there. Its going to need a inductor and diode, so I need to cost the current 12V circuit up vs a setup up solution. If there isn't any huge saving in price, then its probably not worth bothering going down that route.

EDIT:

Seems the best part is a texas step-up part which only really needs a external inductor. It can push up to 1Amp. The only machines which may use 12V really are the STE and Falcon (i've not checked) Though I can't imagine more than 100mA is needed. The only thing which may need some beef on the 12V is the old floppy drive which may well need 250mA or thereabouts. I will order a demo board soon to play around with it.

Its not a huge cost saving circuit wise, but those 100uF 35V ceramics are expensive. So if I can move to lower voltage ceramics then it will save costs there, plus the smaller transformer. Problem is time with it all. It would become a new project :( So while the idea is possible, it will probably have to wait until next year now.
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
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