Re: Remote Power Supply Connection



"Trevor Wilson" <trevor@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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"keithr" <keithr@xxxxxxxxxxxxxx> wrote in message
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"Trevor Wilson" <trevor@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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--
Trevor Wilson
www.rageaudio.com.au
"keithr" <keithr@xxxxxxxxxxxxxx> wrote in message
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"Trevor Wilson" <trevor@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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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.

Iain



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