Re: weird cables question

From: Groepaz (
Date: 2004-01-15 13:05:56

On Thursday 15 January 2004 11:27, Spiro Trikaliotis wrote:

> > mmmh... are there really still these cheap 3wire thingies sold? i would
> > assume them having atleast rts/cts aswell, maybe also dcd/dtd.
> Yes, they are. Sometimes, the handshake wires are connected locally on
> each side.

kindof brave to call it nullmodem cable then though :) dcd/dtd is correct to
be bridged, but a missing rts/cts connection is pretty much ridiculous - 
this wont ever work right except when both end are faster than the actual
transfer is. (which is true for connecting two modern pc's i guess, but you'll
run into all kinds of problems with anything else, not even starting with
a c64 :))

> If you connect both C64 into different outlets, connected to different
> phases, then I won't be sure that there will be no damage.

not a real problem since the voltage is stabilized in the PSU... it is a (BIG!)
problem on the other hand with the 9V AC :) (connect them at wrong phase and
*boom* :=P)

> In a company I once worked, I remember people talking about something like
> this, resulting in a cross current of some Ampere in an installation. This
> was not very good. ;-)

no several ampere on the 5v line of a c64 would definetly not be very good :=D

however this problem can be eliminated by throwing in some diodes - and in this
case i am not even sure if the powersupplies themselves, or the c64 board
wouldnt silently supply these :)

> I'm not an electronics engineer, but from my understanding, this is even
> more critical if you have PE and N connected in your house installation,
> which is the case in many old houses.

uhmz well... THAT doesnt make a big difference at all :O) PE and N is
connected anyway, doesnt matter where (in your house or in the powerplant).
its just no more done in new installations because of other security measures.

if the metal case of a certain item is grounded chances are that on a physical
failure of some kind -broken PEN line for example- the metal case will have
high voltage potential -due to contact with L- but the fuse wont blow if the
thing is standing on good isolated ground. "nice" surprise whenever someone
touches the thingy :o) with a seperate PE line this is much less likely to

infact the seperated PE and N cables yield to another (not existant with
the old installations) problem - voltage difference between PE and N - but
thats less worse than the above problem :)


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