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. Mike Sent from: My extremely complicated, hand held electronic device.
On May 2, 2021, at 3:09 PM, Ian Primus via vcf-midatlantic <vcf-midatlantic@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@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@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@gmail.com> *Sent:* 02 May 2021 12:14 *To:* dave.g4ugm@gmail.com *Cc:* vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>; W2HX < w2hx@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@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@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@lists.vcfed.org> On Behalf Of John Heritage via vcf-midatlantic Sent: 02 May 2021 00:45 To: W2HX <w2hx@w2hx.com> Cc: John Heritage <john.heritage@gmail.com>; vcf-midatlantic <vcf- midatlantic@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@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@lists.vcfed.org> On Behalf Of John Heritage via vcf-midatlantic Sent: Wednesday, April 28, 2021 4:57 PM To: Ethan O'Toole <telmnstr@757.org> Cc: John Heritage <john.heritage@gmail.com>; John Heritage via vcf-midatlantic <vcf-midatlantic@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@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