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

[Ian Primus]

I see a lot of very complicated explanations and responses, and a lot
of very technical "what-if's" attempting to consider every single
angle. After all, electronics is the passion of many, myself included.

But at the end of the day, it's a power supply. For a home computer.
It's been designed to work with ordinary household power - it's not
going to be super picky about tiny differences in voltage, and
basically nothing in this entire realm is going to have a problem with
a difference in frequency. That really only affects AC synchronous
motors like in a record player or something.

A step-up transformer is more than sufficient, just get one that's
beefy enough to handle whatever you intend to run. Being that this is
an Amiga, it doesn't exactly pull a ton of power, so nearly anything
should be fine.

I have a whole bunch of equipment from foreign countries. For
operating 240v hardware, I have a couple of step up transformers. One
is simply the isolation transformer scavenged from an old arcade
machine - one that had multiple input taps. I'm using it backwards,
restrapped as 240v, operating it as a step-up. No idea what the
wattage is, but it was meant to power an arcade monitor, so probably
around 100W or so. Ish. It works fine, I've powered lots of British,
Soviet, and other European machines on this thing,

Another step-up I use is actually a travel converter meant to be used
as a step-down, to power 120V stuff overseas, converting 240V to 120V.
It's an autotransformer, so it does not isolate in any way, and this
is likely how most transformers you see on Amazon are built, because
it's cheaper. I've rewired it backwards so it converts the 120V up to
240V. This also works just fine and I've powered lots of foreign
equipment off of it.

Nearly every product on Amazon has some "scary reviews" thanks to
people that simply don't know how to use it. My favorite being from
some lithium batteries, two different people complained they caused
their devices to catch fire and nearly burn down their house, with
photo evidence. One of these photos shows the batteries, burnt and
swollen, in the compartment of the device. One of which is installed
backwards. So, huh. You take two 10,000mah batteries, and short them
out with each other by installing one battery backwards in a device
that uses two batteries in parallel, and it catches fire? Who knew?
Silly physics. What will it think of next? It should have *known* what
this user intended the batteries to do, and not allowed them to
explode like that. So, yes. You have to take reviews with a grain of
salt. While people may have had horrible experiences, there is a
reasonable chance these experiences were self inflicted.

And yes - precise US line voltage is technically 117V, and I'm pretty
sure the UK is technically 230V, etc, etc. But the line voltage will
vary from area to area, and sag during periods of high usage and on
circuits that are heavily loaded. Any device designed for use in the
home will be tolerant of these sorts of voltage drifts, and the
voltage regulation in the power supply of any given home computer, TV
set, or piece of stereo equipment will be able to handle a reasonable
amount of deviation.

In the end, it really doesn't matter - close enough is close enough -
220, 221, whatever it takes. It's fine. Any given step-up transformer
should have no problem powering an Amiga, and any reasonably designed
power supply is going to work just fine on either 50 or 60hz, and
within any reasonable deviation of it's intended input voltage. Power
in houses is FAR from perfect.

-Ian

On Sun, May 2, 2021 at 8:56 AM John Heritage via vcf-midatlantic
<vcf-midatlantic at lists.vcfed.org> wrote:
>
> 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
> > > > >
> > > > >
> > > >
> >
> >