From: David Wood (jbevren_at_starbase.globalpc.net)
Date: 2004-01-12 12:47:19
The primary reason for separate windings, as far as I know, is to get isolation between the +5 ground and the 9vac. The SX-64 user port is known for not working with certain devices because it's not isloated like the breadbox psu is. -David On Mon, 12 Jan 2004 Gianmario.Scotti@nokia.com wrote: > I actually knew that the transformer in the original C-64 PSU has a transformer with two windings, but I am not sure that's really necessary. I think a single winding would be adequate, given enough VA of the transformer. If that's not the case, I'd like to hear why. > > In any case, it's really trivial to use two windings instead of one, in the design I presented. It doesn't increase complexity at all. When I get home I'll prepare another schematic, to work with commodore's original transformer. > > > cheers! > > > mario > > > > > -----Original Message----- > From: email@example.com > [mailto:firstname.lastname@example.org]On Behalf Of ext Hársfalvi Levente > Sent: 12. January 2004 11:50 > To: email@example.com > Subject: Re: C64 power supply replacement > > > Hi!, > > > Gianmario.Scotti@nokia.com wrote: > > > A transformer doesn't have separate taps for 9 V AC *AND* regulated 5 V :o) > > And I did put a fuse in the 9 V AC line in the schematic. > > The transformer in the C64 PSU has two independent secondary circuits, 9V AC > each. One of these circuits is rectified and regulated (5V DC), the other is > just brought to the C64 (only a fuse is used). > > See these schematics: > > http://www.funet.fi/pub/cbm/schematics/computers/c64/c64-powersupply.gif > http://www.funet.fi/pub/cbm/schematics/computers/c64/c64extps.gif > > As you see, the two outputs (5V dc, 9V ac) are fully "independent" in the > original PSU design. They aren't grounded together in the PSU. > > > Regards, > > L. > > > > Message was sent through the cbm-hackers mailing list > > > Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing list
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