RE: Sensing my garage door

["Paul" <p-gale@xxxxxxx>]

Thanks Frank - to the rescue again!



The open/close lines are a simple switch closure type so I guess fairly
easy for HV to $B!F(Bclose$B!G(B the switch (or do I need a relay?).



The other lines are a bit more difficult. I$B!G(Bve simply taken a line
from gnd on the garage door opener and directly from the microswitch
terminals. These show +5V respectively when the door is open and closed.
Obviously if I take these signals and connect them through the input of the
opto - I would short-circuit the door opener (not good).



What I need to know is how to $B!F(Bsense$B!G(B the 5V signals without
interfering with the garage door circuit.



Thanks,



Paul.



-----Original Message-----
From: Frank Mc Alinden [mailto:armagh@xxxxxxx]
Sent: 05 April 2003 10:58
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Sensing my garage door



Hi Paul


> Two lines for the open/close operation - simple!

I take it these are command signals from Homevision ..is that correct ? and
is the logic normally low go high (+5V) or high  go low.......

I will do a schematic and get it off to you on the above assumption

Frank

----- Original Message -----
From: "Paul" <p-gale@xxxxxxx>
To: <ukha_d@xxxxxxx>
Cc: "Frank Mc Alinden" <armagh@xxxxxxx>
Sent: Saturday, April 05, 2003 7:30 PM
Subject: [ukha_d] Sensing my garage door


> One for the electronics experts:
>
>
>
> In an attempt to remotely control and sense the condition of my garage
> door, I've run several signals back from my garage door opener as
> follows:
>
>
>
> Two lines for the open/close operation - simple!
>
> Three lines taken from the position micro switches - Gnd, +5V when
open,
> +5V when closed.
>
>
>
> I'm trying to feed the microswitch signals into an opto-isolated
simple
> circuit and then into HomeVision so that I can tell when the door is
> open/closed. The trouble is, I don't want to affect the garage door
> opener in any way (and break it!).
>
>
>
> I've currently got one of the gnd and +5V signals fed into the input
of
> the opto with a 1K resistor in series. Is this enough? How can I
> maintain the +5V potential of the garage door circuit (and effectively
> not effect it) but at the same time sense the voltage (very high value
> resistor instead of the 1K???). Does that make sense?
>
>
>
> If anyone can help (Frank?), I can sketch the setup if my explanation
is
> not clear.
>
>
>
> TIA  :-)
>
>
>
> Paul.
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
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http://www.automatedhome.co.uk/article.php?story_id=1110
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