Yes, 12.7V would be nominal for a properly designed adapter. Maybe the wide range of voltages I’ve seen coming from these things is their way to compensate for poorly designed, poorly manufactured cheap transformers they put in these things? The 5V regulator in the Poly-800 doesn’t seem to have any trouble filtering the noise from a cheap switching adapter, but I suppose you would want to keep the adapter far away from something like a wireless mike receiver.
Don B.
From:
korgpolyex@yahoogroups.com [mailto:
korgpolyex@yahoogroups.com ] On Behalf Of Gordon JC Pearce
Sent: Saturday, December 22, 2012
2:20 PM
To: korgpolyex@yahoogroups.com
Subject: Re: [korgpolyex] Re: New
Power Adaptor for Poly 800 and question about multi mods (Hawk)
On 22/12/12 19:08, backshall1 wrote:
> really needs more than 300ma then the voltage will drop below 9 volts. A
Mmm, not quite. An unregulated supply typically puts out √2Vnominal so
> large transformer type adapter that is rated for 1000ma might measure as
> high as 20V with no load on it, and only drop to 15 volts with only a
> 300ma load on it.
for a 9V unregulated supply you'd expect to see about 12.7V offload,
regardless of the output current.
> On the other hand, if you are using a newer switching-type adapter, it
The output is generally electrically quieter, too, although they can
> is probably much smaller since it does not need a big transformer in it,
> and it will put out a regulated 9V at any current level from 0-1000ma,
crowbar some nasty noise onto the mains supply. RFI can be a problem
with cheap ones, too.
> so there is no problem using one rated for 1000ma. A/C adapters rarely
... or weight ;-)
> have markings on them to show whether they are switching supplies or
> not. You can usually tell from the size.
--
Gordonjcp MM0YEQ