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

[Ian Primus]

While a shit in frequency is certainly something that *can* cause
problems, it's not going to be something that will be a problem
running equipment designed for 50hz on 60hz power, as the higher
frequency simply won't saturate the transformer core. Same reason you
can use old radios meant for 25hz power just fine on 60hz. The 25hz
transformers are absolutely huge to compensate for this and to avoid
saturating on such a low frequency - totally unnecessary for 60hz, but
they work just fine, and run cool too!

The only time a problem might crop up is running 60hz equipment in
50hz countries, but... the difference is fairly minor, and the
transformer would have to be really on the ragged edge of saturation
to begin with to not function correctly with the change. Definitely
something to consider, however. But that's not the problem we're
dealing with here, because he's using stuff at a higher frequency than
it was designed for, not lower.

-Ian

On Sun, May 2, 2021 at 8:00 PM W2HX via vcf-midatlantic
<vcf-midatlantic at lists.vcfed.org> wrote:
>
> > 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.
>
> Unfortunately not entirely true, but the power supply gods have smiled upon you. So the op has a switch mode supply and all is well he will not have to worry. In fact, depending on the specs, he may not even need a step up transformer at all if the supply has a broad input range.
>
> The problem with frequency (however small it may be) is that it can cause the core in the main transformer to saturate. This can have various nasty effects like heating and also could induce RFI on the output of the PS. Of course, this all depends on how well the transformer is made. A marginally spec'd unit could exhibit this problem. A better-spec'd unit may not.
>
> So there is something more than a zero percent reason to worry about it, but clearly less than 100%.
>
> 73 Eugene W2HX
>
>
> -----Original Message-----
> From: vcf-midatlantic <vcf-midatlantic-bounces at lists.vcfed.org> On Behalf Of Chris Fala via vcf-midatlantic
> Sent: Sunday, May 2, 2021 4:06 PM
> To: vcf-midatlantic <vcf-midatlantic at lists.vcfed.org>
> Cc: Chris Fala <chrisjpf33 at gmail.com>
> Subject: Re: [vcf-midatlantic] OT - 120v to 240v step up recommendations
>
> Exactly!
>
>
>
>
> On Sun, May 2, 2021 at 3:10 PM Ian Primus via vcf-midatlantic < vcf-midatlantic at lists.vcfed.org> wrote:
>
> > 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
> > > > > > >
> > > > > > >
> > > > > >
> > > >
> > > >
> >