Re: Connecting PIR's to an X-10 Controller

[Steve Morgan <steve@xxxxxxx>]

Thanks, Keith.

I had a feeling you'd come up with the answer.

I'm off to Maplin to get the bits later today and I'll phone Laser for a
controller (don't want to wreck any of the existing ones).

I'm going to use opto-isolators, as you've suggested, with status LEDs.
I'll change to resistors for 560R, as I reckon this should give me just
under 16mA open, 22mA closed (I think that makes the power dissipation
just over 0.26w, so I'll use 0.6w, sound OK?). I'll have to do some
closer examination of the controller now, as I've got to make sure I
connect the transistor the right way (I was taking the easy route using
relays!).

I thought I'd put it all in a nice box (including the controller) with a
decent PSU and 5-pin DIN connectors for the sensors. I'll wire to
provide power and allow NO or NC contacts so I've got that bit more
flexibility.

I'll let you know how I get on.

Cheers,
Steve
-----Original Message-----
From: Keith Doxey [mailto:keith.doxey@xxxxxxx]
Sent: Monday, May 31, 1999 10:36 PM
To: 'ukha_d@xxxxxxx'
Subject: [ukha_d] Re: Connecting PIR's to an X-10 Controller


Hi Steve,

Havent tried it but I see no reason why it wouldnt work.
I have interfaced to a number of CD players and videos etc by connecting

Relays, Optoisolators or even just pushbuttons across the existing
switches. From past experience, I would ALWAYS use something that
isolates
the two parts of the circuitry (my preference is opto isolators as you
get
4 in a package and they are totally silent in operation) as long leads
can
sometimes pick up interference that can stop the device from operating.

One thing to be aware of is that the circuitry of the X10 controller is
NOT
ISOLATED FROM THE MAINS so you must use one of the above methods which I

notice you were planning to do anyway.

Using your proposed method, I assume that the relays you add will be
constantly energised until motion is detected. The relays could get
quite
warm in operation. By using Opto-Isolators you could wire them as
follows.

+12volt supply via a 1K resistor to the LED in the isolator then LED to
ground.
Connect the PIR contact ACROSS the LED
Connect the Transistor in the opto across the controller button.

When the PIR is not active (contacts closed) the 12 volt supply flows
through the 1K resistor to ground (LED shorted by contact)
Optotransistor
not operated so button not pressed.

When motion is detected (contacts open) the 12 volt supply flows through

the resistor and LED to ground. Optotransistor operates effectively
pressing the button.

This would probably use less power than the relays as the current would
be
about 12mA idle and 10mA when the LED was active.

An added feature could be status indication by reducing the resistor
value
slightly and adding a visible LED in series with the other OptoLED. In
addition to looking pretty it would also show what sensor was flooding
your
house with X10 signals.

As mentioned earlier.....with an ILQ74 you can do 4 circuits with single
16
pin chip.

Hope that helps

Keith

http://www.btinternet.com/~krazy.keith
Krazy Keith's World of DIY Home Automation

-----Original Message-----
From:	Steve Morgan [SMTP:steve@xxxxxxx]
Sent:	31 May 1999 16:19
To:	ukha_d@xxxxxxx
Subject:	[ukha_d] Connecting PIR's to an X-10 Controller

Folks,

I'm looking to interface a number of PIR's to my X-10 based HA system
(internal and external).

My question is, has anyone tried modifying a standard X-10 controller,
such as SC502/503 maxi controllers or MC460 to use an external switched
input instead of the pushbuttons?

Having looked at one of my IR543's, the buttons are all the typical
metal-bubble type that short out the PCB tracks when pressed.

My idea is to bring these tracks out of the box and allow them to be
switched by the PIR's. Since the PIR's generally have normally-closed
connections, I thought I'd use another small SPDT relay as a kind of
'inverter' so the pads would be shorted when the PIR contacts open.

It strikes me that this is rather cheaper than using a powerflash module
with each PIR as I get 8 or 16 'channels' with one controller.

What do you think? Any particular suggestions?

Cheers
Steve


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