Well, firstly, the 81 psu has a different plug on the end, ie a jack,
whereas the Spectrum one has one of those inside out connectors with the
hole in the middle.

Now assuming you can get the polarity right and the connectors right....

First of all you suggest the 81 psu is quite a high current one, but as i
recall, the 81 was supplied with a pretty lame psu, and if you bought a zx
printer, they supplied the higher current psu so it would work.

Unfortunately for you, the psus are not regulated internally, so if you plug
in the eu one, if as you say it is indeed rated at a lower input voltage, it
will output a higher voltage too. This may be OK, but as the Speccy has a
slight tendency (irony) to overheat in any case, it may get slightly warmer,
but you should be fine if you use it in the fridge...:-)

Seriously, I'd get myself a regulated supply which will run on a range of
voltages. They are not that expensive.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: briang1@blueyonder.co.uk
__________________________________________________ __________________________________________________ __________


wrote in message
news:7a0ffb0e-41e9-4bb3-82a1-2f236b0ce8de@e23g2000prf.googlegroups.com...
> Hello,
> I have a couple of questions about ZX Power Supply Compatibility.
> I own a ZX Spectrum from Italy and a ZX81 from UK, both with original
> ZX Power Supply: the first is marked EURO 1400 and turns 220V ac @50Hz
> into 9V dc @ 1.4A, the second is marked UK1200 and turns 240V ac @50Hz
> into 9V dc @ 1.2 A.
> Provided that I am in Italy, are the two power supplies compatible, so
> that i can use my EURO1400 supply with both the ZXs? Or I better use
> each with its original supply, even if the ZX81 UK1200 supply is
> designed for UK mains?
> Thank you very much in advance for your help!
>
> Edoardo
> Italy

On 13 Dic, 09:21, "Brian Gaff" wrote:
> Well, firstly, the 81 psu has a different plug on the end, ie a jack,
> whereas the Spectrum one has one of those inside out connectors with the
> hole in the middle.
>
> Now assuming you can get the polarity right and the connectors right....
>
> First of all you suggest the 81 psu is quite a high current one, but as i
> recall, the 81 was supplied with a pretty lame psu, and if you bought a zx
> printer, they supplied the higher current psu so it would work.
>
> Unfortunately for you, the psus are not regulated internally, so if you plug
> in the eu one, if as you say it is indeed rated at a lower input voltage, it
> will output a higher voltage too. This may be OK, but as the Speccy has a
> slight tendency (irony) to overheat in any case, it may get slightly warmer,
> but you should be fine if you use it in the fridge...:-)
>
> Seriously, I'd get myself a regulated supply which will run on a range of
> voltages. They are not that expensive.
>
> Brian
>
> --
> Brian Gaff....Note, this account does not accept Bcc: email.
> graphics are great, but the blind can't hear them
> Email: bria...@blueyonder.co.uk
> __________________________________________________ _________________________-___________________________________
>
> wrote in message
>
> news:7a0ffb0e-41e9-4bb3-82a1-2f236b0ce8de@e23g2000prf.googlegroups.com...
>
>
>
> > Hello,
> > I have a couple of questions about ZX Power Supply Compatibility.
> > I own a ZX Spectrum from Italy and a ZX81 from UK, both with original
> > ZX Power Supply: the first is marked EURO 1400 and turns 220V ac @50Hz
> > into 9V dc @ 1.4A, the second is marked UK1200 and turns 240V ac @50Hz
> > into 9V dc @ 1.2 A.
> > Provided that I am in Italy, are the two power supplies compatible, so
> > that i can use my EURO1400 supply with both the ZXs? Or I better use
> > each with its original supply, even if the ZX81 UK1200 supply is
> > designed for UK mains?
> > Thank you very much in advance for your help!
>
> > Edoardo
> > Italy- Nascondi testo tra virgolette -
>
> - Mostra testo tra virgolette -

On 13 Dic, 09:21, "Brian Gaff" wrote:
> Well, firstly, the 81 psu has a different plug on the end, ie a jack,
> whereas the Spectrum one has one of those inside out connectors with the
> hole in the middle.
>
> Now assuming you can get the polarity right and the connectors right....
>
> First of all you suggest the 81 psu is quite a high current one, but as i
> recall, the 81 was supplied with a pretty lame psu, and if you bought a zx
> printer, they supplied the higher current psu so it would work.
>
> Unfortunately for you, the psus are not regulated internally, so if you plug
> in the eu one, if as you say it is indeed rated at a lower input voltage, it
> will output a higher voltage too. This may be OK, but as the Speccy has a
> slight tendency (irony) to overheat in any case, it may get slightly warmer,
> but you should be fine if you use it in the fridge...:-)
>
> Seriously, I'd get myself a regulated supply which will run on a range of
> voltages. They are not that expensive.
>
> Brian
>
> --
> Brian Gaff....Note, this account does not accept Bcc: email.
> graphics are great, but the blind can't hear them
> Email: bria...@blueyonder.co.uk
> __________________________________________________ _________________________-___________________________________
>
> wrote in message
>
> news:7a0ffb0e-41e9-4bb3-82a1-2f236b0ce8de@e23g2000prf.googlegroups.com...
>
>
>
> > Hello,
> > I have a couple of questions about ZX Power Supply Compatibility.
> > I own a ZX Spectrum from Italy and a ZX81 from UK, both with original
> > ZX Power Supply: the first is marked EURO 1400 and turns 220V ac @50Hz
> > into 9V dc @ 1.4A, the second is marked UK1200 and turns 240V ac @50Hz
> > into 9V dc @ 1.2 A.
> > Provided that I am in Italy, are the two power supplies compatible, so
> > that i can use my EURO1400 supply with both the ZXs? Or I better use
> > each with its original supply, even if the ZX81 UK1200 supply is
> > designed for UK mains?
> > Thank you very much in advance for your help!
>
> > Edoardo
> > Italy- Nascondi testo tra virgolette -
>
> - Mostra testo tra virgolette -

Hi Brian,
thank you for replying. I actually did not notice the end plug... I
suppose getting a general purpose regulated supply is really the best
solution.

Edoardo

On 13 Dic, 09:29, ingpi...@inwind.it wrote:
> On 13 Dic, 09:21, "Brian Gaff" wrote:
>
>
>
>
>
> > Well, firstly, the 81 psu has a different plug on the end, ie a jack,
> > whereas the Spectrum one has one of those inside out connectors with the
> > hole in the middle.
>
> > Now assuming you can get the polarity right and the connectors right....
>
> > First of all you suggest the 81 psu is quite a high current one, but as i
> > recall, the 81 was supplied with a pretty lame psu, and if you bought a zx
> > printer, they supplied the higher current psu so it would work.
>
> > Unfortunately for you, the psus are not regulated internally, so if you plug
> > in the eu one, if as you say it is indeed rated at a lower input voltage, it
> > will output a higher voltage too. This may be OK, but as the Speccy has a
> > slight tendency (irony) to overheat in any case, it may get slightly warmer,
> > but you should be fine if you use it in the fridge...:-)
>
> > Seriously, I'd get myself a regulated supply which will run on a range of
> > voltages. They are not that expensive.
>
> > Brian
>
> > --
> > Brian Gaff....Note, this account does not accept Bcc: email.
> > graphics are great, but the blind can't hear them
> > Email: bria...@blueyonder.co.uk
> > __________________________________________________ _________________________--___________________________________
>
> > wrote in message
>
> >news:7a0ffb0e-41e9-4bb3-82a1-2f236b0ce8de@e23g2000prf.googlegroups.com...
>
> > > Hello,
> > > I have a couple of questions about ZX Power Supply Compatibility.
> > > I own a ZX Spectrum from Italy and a ZX81 from UK, both with original
> > > ZX Power Supply: the first is marked EURO 1400 and turns 220V ac @50Hz
> > > into 9V dc @ 1.4A, the second is marked UK1200 and turns 240V ac @50Hz
> > > into 9V dc @ 1.2 A.
> > > Provided that I am in Italy, are the two power supplies compatible, so
> > > that i can use my EURO1400 supply with both the ZXs? Or I better use
> > > each with its original supply, even if the ZX81 UK1200 supply is
> > > designed for UK mains?
> > > Thank you very much in advance for your help!
>
> > > Edoardo
> > > Italy- Nascondi testo tra virgolette -
>
> > - Mostra testo tra virgolette -
>
> Hi Brian,
> thank you for replying. I actually did not notice the end plug... I
> suppose getting a general purpose regulated supply is really the best
> solution.
>
> Edoardo

Hi Edoardo,

As for the ZX PSU, I am trying to use an used ATX PC PSU. It's
switching, gives more power than you could dream of, and it's
shielded.

More than else, it's got two interesting voltages: +5V and +12V. I
will try to replace the internal 7805 voltage regulator with a direct
connection with the +5V of the PSU, and of course use the +12 V output
to obtain a +9V useful for the rest of the ZX Spectrum. I just don't
know if might be useful to connect some extra capacitor, but I don't
think it's that critical (there shouldn't be a great lag between the
+9V and +5V using the ATX PSU).

With it, I think I might power up just ANY kind of addon I want to,
from Interface 1 to ZX Printer, to DiscIple and so on, without any
worry. And powering up the ZX Spectrum would be as easy as tapping the
ON button; plus, the ZX Spectrum would heat up far less, just wiping
out the 7805.

I will report ASAP.

Mentore

Mentore ha scritto:

> As for the ZX PSU, I am trying to use an used ATX PC PSU. It's
> switching, gives more power than you could dream of, and it's
> shielded.
>
> More than else, it's got two interesting voltages: +5V and +12V. I
> will try to replace the internal 7805 voltage regulator with a direct
> connection with the +5V of the PSU, and of course use the +12 V output
> to obtain a +9V useful for the rest of the ZX Spectrum.

Beware that most switching PSU need a certain level of loading or the
regulation would not be reliable,
probably the spectrum won't draw enough current to satisfy this
requirement.

Cheers,
fatpig

On 13 Dic, 17:28, fatpig wrote:
> Mentore ha scritto:
>
> > As for the ZX PSU, I am trying to use an used ATX PC PSU. It's
> > switching, gives more power than you could dream of, and it's
> > shielded.
>
> > More than else, it's got two interesting voltages: +5V and +12V. I
> > will try to replace the internal 7805 voltage regulator with a direct
> > connection with the +5V of the PSU, and of course use the +12 V output
> > to obtain a +9V useful for the rest of the ZX Spectrum.
>
> Beware that most switching PSU need a certain level of loading or the
> regulation would not be reliable,
> probably the spectrum won't draw enough current to satisfy this
> requirement.

Didn't know this problem. Could you point me somewhere to read more?

Thanks.
Mentore

> > Beware that most switching PSU need a certain level of loading or the
> > regulation would not be reliable,
> > probably the spectrum won't draw enough current to satisfy this
> > requirement.
>
> Didn't know this problem. Could you point me somewhere to read more?

If you just want to check the existence of the requirement search the
power supply manufacturers data sheets by seraching for "atx psu
minimum load" or "switching regulator minimum load" you will find
quickly several references. Unfortunately this information is not
available for the cheap psu but as a
rule of thumb you must draw at least about 15% of the maximum current
from both +5v and +12V outputs to have the psu working reliably.

If you know some electronics here is a link to a short explanation:
http://www.smpstech.com/mtblog/minim...pply_load.html

and a little more detailed analisys:
http://www.rason.org/Projects/swregdes/swregdes.htm