Microdisc PSU

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
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Igotafro
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Microdisc PSU

Post by Igotafro » Mon Sep 24, 2012 12:01 pm

Does anyone have a schematic over the Microdisc power supply? I missing mine and was thinking of making my own. My Microdisc uses a LM323 (which is positive) and the Oric uses a 7905 (which is negative), so I'm a little confused as to how they get a common ground.

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kenneth
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Re: Microdisc PSU

Post by kenneth » Mon Sep 24, 2012 12:47 pm

Hello Igotafo

The oric and the microdisc use a independant transformer for each one (it is not a general power unit like PC) then in a "floating voltage" configuration you can connect these two devices without shortcut circuit problem. (the -5v Oric become 0v Microdisk)
The problem of the 7905 negative regulator is the impossibility to connect a transformer alone (single coil) for the both devices.

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Silicebit.
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Re: Microdisc PSU

Post by Silicebit. » Mon Sep 24, 2012 9:33 pm

Then... The transformer inside of microdisc psu has three output windings? One for Oric computer, one for 5V microdisc and one for 12V microdisc?
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Igotafro
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Re: Microdisc PSU

Post by Igotafro » Tue Sep 25, 2012 3:31 pm

I made a schematic for my PSU plans, see below. I'm not sure exactly what transformers I should use though. The Oric input wants 9V unregulated DC as the schematic says, I guess then U1 should be around 7V or something? I've never designed a PSU before :)
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Silicebit.
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Re: Microdisc PSU

Post by Silicebit. » Tue Sep 25, 2012 6:54 pm

I'm using a 7.5V 1A psu to power my Atmos and it work fine and cold. I recommend use a 7.5V psu instead a 9V psu for 7905/7805 regulators.

Igotafro, I suggest to use a transformer with 7.5Vx2 1A or 1.5A windings to feed 7905 and LM323, and a 15V 1A transformer to feed to 7812.
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