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

Herb Johnson hjohnson at retrotechnology.info
Sun May 2 16:04:20 UTC 2021

OK, John, this discussion thread got my attention for some reason, 
although I'm not an Amiga 500 owner, maybe because I'm a decreed 
electrical engineer. But pardon me, your subject line really is 
distracting. Your real subject-line is "power supplies for Amiga 500" 
which is certainly on-topic.

The real issue from reading your posts, is this. YOu have an Amiga 500 
with some additions and accessories, which you want to power. Amiga 
500's operate from an external AC to DC power supply, with a DC cable to 
the Amiga (this not being known to some of us). You are about to 
receive, an iCOMP brand power supply - but it's European with a 240V 
Euro style plug. Your question was/is: how do I run this in the USA?

Turns out: you said you can contact the iCOMP producer - they have a WEb 
site, they have a forum - and you already asked them if the power supply 
cares about 60Hz versus 50Hz AC power. They said "no".

So: you can ask them, about use of any common, AC step-up transformers 
to convert US AC power and AC outlets, to Euro AC power and AC outlets. 
But read on, you have other questions to ask (by my best guesses, I'm 
not an Amiga owner).

Ask them about the "wattage", that being how those transformers and 
their power supply are rated. "wattage" is simply AC voltage (110, 240) 
times the desired current in Amps. If your Amiga consumes say 100 watts 
power, it needs about 1 Amp of 110V AC current through a transformer; or 
1/2 Amp of 240V AC current (roughly). This is a *rating*, so you want 
transformers   that can "deliver" more than 100 watts; not all of that 
will be necessary, that's OK.  "100 watts" is an example, I don't know 
what you need.

My own experience (and as posted) is that these step-up transformers are 
relatively cheap and common, available from eBay, Amazon, other online 
vendors; and from any shops that cater to foreign visitors to the United 
States. I see these in thrift stores sometimes (in New Jersey). They 
don't care about 50Hz or 60Hz, and your iCOMP vendor says his supplies 
also don't care. That's not totally correct but that's probably OK.

The remaining issue is: does the iCOMP power supply, have sufficient DC 
power for your A500? (whatever other issues it may have as something you 
just bought). I ask because I did some homework, went to the iCOMP Web 
site, saw they had a forum, and saw this post:


The post says more or less: someone bought some new model of ICOMP's 
"CA-PSU", two units; they worked both in one Amiga 500 they have, but 
neither worked with an Amiga 1200 they have; they measure DC volts out 
at 4.85 on the failing units; but "My A500 PSU is pretty solid at 5.1V" 
(apparently a 3rd power supply).

Hint: when DC power supplies can't deliver enough power, their voltage 
drops. just over 5 volts is what you want; under 5V is not desirable.

So: this is where "wattage" comes in to play. With DC power, Plan A is 
you figure it out by measuring each DC voltage, each times the DC 
current consumed, and then add those wattages up. It's easy to measure 
DC current with a voltmeter; a little harder to measure current because 
you have to run power through your voltmeter (ammeter) to do so.

But "plan B", would be to ask other Amiga 500 owners, if this 
wattage-stuff is a problem, what their Amiga 500's consume or their 
power-supply ratings, if they use this specific brand/model year supply 
(maybe in Europe?), ask icomp.de, etc.

And so: pardon me, but your real post, is about "getting good power to 
your Amiga 500" - with whatever configuration you have, if it works or 
not right now - and whether this iCOMP unit combined with some AC 
step-up transformer will do the job or not. Of course  it's your thread 
and your situation. Good luck.

Regards, Herb Johnson

Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT comcast DOT net

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