Re: Remote Power Supply Connection

-- 
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 you can open either cover, pull the cable and stick it in your mouth 
> fast enough to beat the relays, then you deserve what you get. It also 
> prevents arcing from trying to pull the cable under power.
>
> I have seen this sytem used in a number of pieces of professional 
> equipment. If the gear uses serious amounts of DC power, you have no 
> alternative to a separate power supply and transferring DC over a cable.

**There already IS an alternative. A good one - Use AC. Switching AC is 
easy. Using AC on connectors is easy. Using high Voltage DC is just dumb. 
I'll wait while you find that relay.


-- 
Trevor Wilson
www.rageaudio.com.au