Re: Remote Power Supply Connection

"Iain Churches" <IainNG@[EMAIL PROTECTED]
> wrote in message 
news:zX9Xj.1633$_03.491@[EMAIL PROTECTED]
>
>
> "Ian Iveson" <IanIveson.home@[EMAIL PROTECTED]
> wrote in message
> news:crMWj.5272$1q4.981@[EMAIL PROTECTED]
>> Trevor Wilson wrote:
>>
>>>>
>
>> Also, transferring the filter caps to the amp would mean that both plug
>> and socket would be live at the time of parting. I have seen it said
that
>> a diode in the amp solves this problem, but I wouldn't entrust my life
to
>> that solution.
>
> You have to use a method (something like a sensing loop
> with a relay) to shut of the DC from the connectors if the
> cable is disconnected at either end.  If a round connector
> is chosen, it must be one one with a deep screw collar or
> bayonet latch, so there is no access to the pins while the
> connector is still making contact. That is why an octal plug
> socket cannot be used, although Patrick seems to have
> found an innovative way to make that combination safe.
>
> Common sense would dictate the fitting and removal of
> the DC umbilical only when the amplifier and PSU have
> bveen switched off for some time.
>
> A power diode, as an additional safety measure works
> well. These are well-proven techniques from rack-mounted
> broadcast equipment in the tube era.  But it is also im****tant
> to comply with modern safety standards.
>
> Iain


The simplest way of ensuring the maximum safety is to have a sensing pin 
that switches the power on both sides and to make that pin shorter than
the 
power pins. For increased safety, you apply a short delay before pulling
the 
relays in , but drop than instantly if the safety loop is opened.

Keith

PS it is also nice to have the earth pin a little longer than the rest, 
although with a tube amp it propbablt isn't really needed.