[iyonix-support] Re: Some Guidance Required Please

  • From: charles <charles@xxxxxxxxxxxxxxxxxxxxxxx>
  • To: iyonix-support@xxxxxxxxxxxxx
  • Date: Tue, 03 May 2011 23:57:35 +0100

In article <5247c9cd51.Andrew-Pin@xxxxxxxxxxxx>,
   Andrew Pinder <Andrew.Pinder@xxxxxxxxxxxxx> wrote:
> In message <f830bdcd51.davehigton@xxxxxxxxxxxxx>
>  on 3 May 2011 Dave Higton <davehigton@xxxxxxxxxxxxx> wrote:

> > In message <51cbb06213julie@xxxxxxxxxxxxxxxxxxxxxxx>
> >           Julie <julie@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

> >> I have never been able to understand why the voltage is this critical.
> >> Neither does my OH. We are both electronics engineers. Back in the
> >> good old days, TTL would tolerate 4.75 - 5.25V, 7V absolute max.
> >> CMOS could run anywhere between 3V and 18V. (I know that many of the
> >> more recent ICs run at 3.3V.) Why is the Iyonix so sensitive?

> > JB has given the real answer: the Iyonix isn't particularly
> > sensitive, but its PSU ages and malfunctions.

> I realise that designing and producing the Iyonix was a major 
> achievement by a small firm and that there must have been complex 
> trade-offs but:

> 1 Acorn hardware tended to last a long time.  So it was likely that 
> buyers would expect the Iyonix to carry on performing even with its 
> PSU ageing.  Of course, if Castle had been able to produce completely 
> new models every 12 months this wouldn't have been an issue.

> 2 Given that PSUs ageing will happen in largely predictable ways,

i don't think they do.  My Iyonix, one of the very early ones had a power
suppply failure at about 15 months.  The replacement one (from Castle) has
worked perfectly since then.


> a design that could cope with the ripple on the 5V line going out of
> spec would be more robust and hence more durable than one that can't.

since Castle were reliant on off-the shelf components, this is rather an
impossible request.

-- 
From KT24 

Using a RISC OS computer running v5.16 

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