RE: Homevision inputs and ground

["Keith Doxey" <ukha@xxxxxxx>]

You shouldnt have any problems for sensors an long as the 0V of
whatever
device you are connecting to HomeVision is either floating ( not grounded
)
or connected to a true ground.

Ground loops tend only to be noticeable on Audio and Video signals.
Audio
will have an audible hum whereas Video will either be unstable or have
a
lighter or darker band moving up or down the screen.

What you must NOT do is connect POWER from more than 1 source to
HomeVision.
It is OK to feed sensors from HV's 5V rail or a dedicated PSU but if
you
were to additionally join up the +5V rail from several devices to HV's
+5V
then the PSU with the highest output ( typically all PSU's will vary by
a
few millivolts ) would then be powering all devices. Also turning off a
piece of equipment would result in it still being powered by another
PSU.

Keith

www.diyha.co.uk
www.kat5.tv


-----Original Message-----
From: Paul S. Gale [mailto:groups@xxxxxxx]
Sent: 04 February 2003 16:04
To: ukha_d@xxxxxxx
Subject: [ukha_d] Homevision inputs and ground


I'm about to connect by garage door opener to HomeVision. I'm tapping
off the +5V output from two microswitches which are triggered when the
door is open and closed respectively (a neat way of sensing I though).



HV needs a common ground and +5V signal applied to an input port. The
question is - if, in the future, I want to monitor something else
similar that has it's own ground or 0V, will I run into problems
connecting all the grounds together? (what's a ground loop so often
spoken about by Keith D?)



Paul.





[Non-text portions of this message have been removed]


http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx 
Subscribe:  ukha_d-subscribe@xxxxxxx 
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx 
List owner:  ukha_d-owner@xxxxxxx
List of UKHA Groups here - http://groups.yahoo.com/group/UKHA_Grouplists/

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


[Non-text portions of this message have been removed]



http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx 
Subscribe:  ukha_d-subscribe@xxxxxxx 
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx 
List owner:  ukha_d-owner@xxxxxxx
List of UKHA Groups here - http://groups.yahoo.com/group/UKHA_Grouplists/

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.