[vcf-midatlantic] OT - 120v to 240v step up recommendations

John Heritage john.heritage at gmail.com
Sun May 2 12:55:36 UTC 2021


Ok so you recommend just getting a step up transformer and be done with it ?

Any brands you recommend that are UL or similar? (Or anyone else
recommend?) .  The models on amazon almost all seem to have at least a
percentage of very scary reviews..

On Sun, May 2, 2021, 8:03 AM <dave.g4ugm at gmail.com> wrote:

> John,
>
> I like to keep equipment original so would not be tempted to mess. In
> addition is the new supply accurate. I run my NTSC CoCo off a transformer
> and its fine.
>
>
>
> The AC does permeate a little past the transformer, so the diodes and
> smoothing capacitor will usually see 100Hz or 120Hz ripple. (a full wave
> bridge rectifier acts as a frequency doubler.)
>
> In theory there could be components tuned to this frequency, but even so
> they would usually not have a high enough “Q” for you to notice or to
> affect the operation.
>
>
>
> Dave
>
>
>
> *From:* John Heritage <john.heritage at gmail.com>
> *Sent:* 02 May 2021 12:14
> *To:* dave.g4ugm at gmail.com
> *Cc:* vcf-midatlantic <vcf-midatlantic at lists.vcfed.org>; W2HX <
> w2hx at w2hx.com>
> *Subject:* Re: [vcf-midatlantic] OT - 120v to 240v step up recommendations
>
>
>
> Thanks Dave, Dave,  and everyone - I reality do appreciate the comments
> and thoughts.
>
>
>
> The computer in question is the Commodore Amiga 500 (Rev 5A / NTSC) and is
> definitely working fine with my other (120VAC at 60Hz to DC output) power
> supply.   So I'm assuming the only 'risk' item here for 60 hz input would
> be the (AC to DC) power supply created by the engineer and not anything on
> the computer itself.
>
>
>
> In this case I'm planning to run here in the US (= 60 hz AC) so worst case
> it would be a '50 hz transformer running at 60hz'.
>
>
>
> Does the frequency of the mains carry over to the DC side somehow?   One
> other option the guy mentioned was wiring a 12V/5A DC power supply directly
> to the DC to DC converter within the new Amiga power supply, bypassing the
> AC to DC conversion.  This would have the benefit of being a smaller, more
> power efficient (less conversions) and slightly cheaper solution.
>
>
>
> Thanks!
>
>
>
> On Sun, May 2, 2021 at 4:38 AM <dave.g4ugm at gmail.com> wrote:
>
> Even if the grid frequency is "not used for anything" it can still matter.
> Some older, larger computers used resonant transformers and these simply
> won't work.
> Going from the UK/EU 50Hz world to the US 60Hz world is not usually a
> problem. In general transformers are slightly more efficient at 60hz.
> Going the other way can be a problem and US transformers can run warm and
> over heat.
>
> Dave
> G4UGM
>
> > -----Original Message-----
> > From: vcf-midatlantic <vcf-midatlantic-bounces at lists.vcfed.org> On
> Behalf
> > Of John Heritage via vcf-midatlantic
> > Sent: 02 May 2021 00:45
> > To: W2HX <w2hx at w2hx.com>
> > Cc: John Heritage <john.heritage at gmail.com>; vcf-midatlantic <vcf-
> > midatlantic at lists.vcfed.org>
> > Subject: Re: [vcf-midatlantic] OT - 120v to 240v step up recommendations
> >
> > Per the guy who designed it (iComp.De - he makes tons of
> > amiga/commodore custom electronics) - the input frequency doesn't matter:
> >
> > does 60 hz / 240V power vs 50 hz / 240V power matter for this power
> supply
> > if I go the transformer route?
> >
> > It shouldn't - it's a simple rectifier design where grid frequency is
> not used for
> > anything.
> >
> > On Wed, Apr 28, 2021 at 8:13 PM W2HX <w2hx at w2hx.com> wrote:
> >
> > > Are you sure the PS in the amiga is expecting 60 Hertz power? It might
> > > be expecting 50 Hz depending on where it is from. This is a bigger
> > > problem that a transformer won't solve
> > >
> > > -----Original Message-----
> > > From: vcf-midatlantic <vcf-midatlantic-bounces at lists.vcfed.org> On
> > > Behalf Of John Heritage via vcf-midatlantic
> > > Sent: Wednesday, April 28, 2021 4:57 PM
> > > To: Ethan O'Toole <telmnstr at 757.org>
> > > Cc: John Heritage <john.heritage at gmail.com>; John Heritage via
> > > vcf-midatlantic <vcf-midatlantic at lists.vcfed.org>
> > > Subject: Re: [vcf-midatlantic] OT - 120v to 240v step up
> > > recommendations
> > >
> > > Yep - that's exactly what i'm looking for advice on -- I think
> > > transformers are pretty standard/minimalist, but just looking for some
> > > links or models of 'ready to use' step up transformers that will plug
> > > into my US 120V outlet and give me a 240V UK or EU style plug output..
> > >
> > > thanks!
> > >
> > > On Wed, Apr 28, 2021 at 4:49 PM Ethan O'Toole <telmnstr at 757.org>
> wrote:
> > >
> > > > > Hey folks
> > > > > I have a new Amiga PSU coming on from icomp that is 240V only.
> > > > > I'm
> > > > looking
> > > > > for recommendations for a 120 to 240V step up transformer rated
> > > > > for at least 100W (so it doesnt have to work hard).  Preferably
> silent.
> > > Etc.
> > > > > Also what should I avoid in this space ?
> > > >
> > > > I mean you can get a transformer that will take 110 and put out 220
> > > > before the Amiga PSU.
> > > >
> > > > The Amiga runs on voltages that you could find on any ATX power
> supply.
> > > > You could make a cable that would go from the funky square DIN to a
> > > > PC motherboard ATX connector and use any old ATX Flex PSU.
> > > >
> > > >                         - Ethan
> > > >
> > > >
> > >
>
>


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