Re: Remote Power Supply Connection

"Iain Churches" <IainNG@[EMAIL PROTECTED]
> wrote in message 
news:ZZBYj.3870$_03.245@[EMAIL PROTECTED]
>
>
> "Trevor Wilson" <trevor@[EMAIL PROTECTED]
> wrote in message
> news:69fijqF336p9iU1@[EMAIL PROTECTED]
>>
>>
>> "keithr" <keithr@[EMAIL PROTECTED]
> wrote in message
>> news:4832585c$1@[EMAIL PROTECTED]
>>>
>>> "Trevor Wilson" <trevor@[EMAIL PROTECTED]
> wrote in message
>>> news:69c1qjF320bo4U1@[EMAIL PROTECTED]
>>>>
>>>>
>>>> -- 
>>>> Trevor Wilson
>>>> www.rageaudio.com.au
>>>> "keithr" <keithr@[EMAIL PROTECTED]
> wrote in message
>>>> news:4830ce5f$1@[EMAIL PROTECTED]
>>>>>
>>>>> "Trevor Wilson" <trevor@[EMAIL PROTECTED]
> wrote in
message
>>>>> news:69bqsaF321ke3U1@[EMAIL PROTECTED]
>>>>>>> Lets face it the whole safety thing can be fixed. You put the
>>>>>>> connectors at each end under covers. The covers can only be lifted

>>>>>>> by
>>>>>>> removing a screw (or two), under the cover is a micro switch. Long
>>>>>>> before anybody can access the actual connectors, the power is
>>>>>>> switched off by the microswitch. I have seen this on a number of
>>>>>>> pieces of professional equipment, for the safety of both the 
>>>>>>> operator
>>>>>>> and the equipment itself.
>>>>>>
>>>>>> **Except that such a solution only works with AC. DC power requires
>>>>>> that capacitors be discharged as well (I need not remind you that
>>>>>> microswitches are spectacularly unsuited for high Voltage DC).
>>>>>>
>>>>>> AC power cables make far more sense. Using DC is dumb.
>>>>>
>>>>> Use some sense Trevor, you do not switch the power with the
>>>>> micro-switch, you use it to energise a relay or relays.
>>>>
>>>> **I *am* using sense. Find me a relay which can switch (say) 500
Volts
>>>> DC. I'll wait.
>>>>
>>>>>
>>>>> Let me spell it out for you - you supply an unswitched low voltage 
>>>>> from
>>>>> the power supply to the amp. That pulls in a relay that connects the

>>>>> B+
>>>>> input pin(s) to the B+ line in the amp. This voltage is fed back
>>>>> through the cable to a similar switch in the power supply. When both
>>>>> switches are made (optionally after a delay) a relay is pulled in in
>>>>> the power supply which applies B+ to the cable. If either
micro-witch
>>>>> is opened then power is dropped isntantly to both relays. Simple
>>>>> enough?
>>>>
>>>> **It SOUNDS simple. Find me a realy rated for (say) 500 Volts DC.
I'll
>>>> wait.
>>>
>>> If that is a problem then you can switch the mains to the B+
transformer
>>> and short the B+ both in the supply and the amp to ground through a
>>> suitable resistor using a couple more relays (at the earthy end of the
>>> resistor of course). Of course in that case you would need a separate 
>>> low
>>> voltage transformer and you'd need to get the sequencing between the
>>> shorting relays and the mains relay right.
>>
>> **You COULD go to such heroic lengths. Or you could just use AC in the
>> first place. You would save yourself a bunch of money, time and
increase
>> safety.
>>
> You would also totally defeat the object of the exercise.....
> to keep AC (except for the signal) out of the amp chassis.

**I fully understand the rationale of keeping the power transformer off
the 
amplifier chassis. OTOH, it makes zero sense in using DC connections
between 
two chassis, rather than employing some (very cheap) ****elding around the 
rectifiers and associated wiring. The safety aspect of using DC is a
serious 
one, which most seem to have neglected.

-- 
Trevor Wilson
www.rageaudio.com.au