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 <mailto: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 <mailto: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 <mailto:w2hx@w2hx.com> > Cc: John Heritage <john.heritage@gmail.com <mailto:john.heritage@gmail.com> >; vcf-midatlantic <vcf- midatlantic@lists.vcfed.org <mailto: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 <mailto: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 <mailto: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 <mailto:telmnstr@757.org> > Cc: John Heritage <john.heritage@gmail.com <mailto:john.heritage@gmail.com> >; John Heritage via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org <mailto: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 <mailto: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