Microdisc PSU

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
Igotafro
Officer Cadet
Posts: 47
Joined: Tue Feb 05, 2008 3:42 pm

Microdisc PSU

Post by Igotafro »

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.
User avatar
kenneth
Squad Leader
Posts: 515
Joined: Fri Nov 26, 2010 9:11 pm
Location: France PdD
Contact:

Re: Microdisc PSU

Post by kenneth »

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.
User avatar
Silicebit.
Flight Lieutenant
Posts: 313
Joined: Thu Jan 12, 2006 10:18 pm
Location: Madrid, Spain
Contact:

Re: Microdisc PSU

Post by Silicebit. »

Then... The transformer inside of microdisc psu has three output windings? One for Oric computer, one for 5V microdisc and one for 12V microdisc?
Oric user since 1984. YouTube
Igotafro
Officer Cadet
Posts: 47
Joined: Tue Feb 05, 2008 3:42 pm

Re: Microdisc PSU

Post by Igotafro »

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 :)
Attachments
schematic.jpg
schematic.jpg (144.49 KiB) Viewed 9618 times
User avatar
Silicebit.
Flight Lieutenant
Posts: 313
Joined: Thu Jan 12, 2006 10:18 pm
Location: Madrid, Spain
Contact:

Re: Microdisc PSU

Post by Silicebit. »

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.
Oric user since 1984. YouTube
Post Reply