DC power packs are switch mode supplies but those with unregulated AC output which are commonly available have a transformer. On 19/06/2022 9:58 am, ocleide_at_earthlink.net wrote: > That surprises me.....it seems like the most "commonly available" wall-warts these days use switching power supply circuitry..........maybe it differs by country? > > -----Original Message----- > From: Clockmeister <clockmeister_at_internode.on.net> > Sent: Saturday, June 18, 2022 8:51 PM > To: cbm-hackers_at_musoftware.de; tokafondo@tokafondo.name > Subject: Re: LM31T as AC voltage regulator for Commodore computers PSU > > 9VAC transformers are commonly available brand new in plug-packs > (wall-warts) or as individual components from most electronics suppliers. > > > > On 19/06/2022 5:17 am, tokafondo_at_tokafondo.name wrote: >> I will only say that this is an actual Commodore (and retro computers) >> desert. And most 9V adapters I've ever seen are from xDSL routers, AP >> and modems, long ago discarded. >> >> >> >> 18 de junio de 2022 22:12, "Mike Stein" <mhs.stein_at_gmail.com >> <mailto:mhs.stein_at_gmail.com?to=%22Mike%20Stein%22%20<mhs.stein@gmail.com>>> >> escribió: >> >> Well, he's in Spain and you're in Italy; maybe you treasure the >> old traditional ways more than he ;-) >> I don't know offhand how constant the 9V load of a C64 is but I >> would think that a carefully selected resistor with maybe a couple >> of Zeners to clamp any overvoltage might do the trick. >> m >> On Sat, Jun 18, 2022 at 2:27 PM Francesco Messineo >> <francesco.messineo_at_gmail.com >> <mailto:francesco.messineo_at_gmail.com>> wrote: >> >> On Sat, Jun 18, 2022 at 5:42 PM <tokafondo_at_tokafondo.name >> <mailto:tokafondo_at_tokafondo.name>> wrote: >> > >> > TI's version of the LM317T's datasheet has something >> interesting to see in its page 15. >> > >> > It can be seen only in TI's datasheet, and not others AFAIK. >> > >> > They show how to use two LM317T IC in a way that from a >> 12VAC source, take it down to 6VAC. I'm sure that with >> changing the values of the resistors needed, 9VAC can be got, >> instead of the 6VAC of the example. >> >> it is actually AC in the sense that there will be alternating >> polarity >> voltages, however that circuit will clamp the waveform voltage >> to 9V >> (or whatever you chose) as long as the input voltage is >> greater than >> the set voltage. So you'll get a kind of "flat-top" waveform. >> I'd say it's not ideal (it adds high frequency harmonics, both >> LM317 >> need to be heatsinked...) >> I have never had any difficulty in finding 9VAC transformers. >> >> Frank IZ8DWF >> >> >> > > >Received on 2022-06-19 07:00:09
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