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

Sentrytv sentrytv at yahoo.com
Sun May 2 19:30:49 UTC 2021

After looking at the picture on the website 
It looks like the power supply is actually a standard switch mode power supply brick which should be able to handle from something like 80 V to 240 V most of them do if I am correct,  if not please correct me.


Sent from:
My extremely complicated, hand held electronic device.

> On May 2, 2021, at 3:09 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

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