Adding extra device to all-in-one PIR lantern

[Zak]

I have a PIR-actived outdoor courtesy light. The PIR and the
lantern's lamp bulb are both inside the same single housing. This
runs off the mains (UK 240 volts). This is it:
http://www.focusdiy.co.uk/content/ebiz/focus/invt/23489/23489.jpg

I would like to modify this so that when the PIR detects something
then I get a notification inside the house. Perhaps from a beeper
or another lamp bulb.

-----

However I can only work with the mains supply because the PIR and
the lamp bulb are effectively one inseperable unit and also are
not easy to access.

Can I interrupt the 3 core mains supply to the lantern as a whole
and insert a device in SERIES (either in the neutral or in the
live lead)such that when the PIR fires and circuit is closed then
this device would actuate?

The impedance of the device woul dhave to be modest or it would
draw power from the PIR circuit and from the bulb circuit causing
both to potentially work wrongly.

Are there any device which would work in this setup? In the old
days maybe a relay would have been inserted in-line with one of
the mains supply wires and the relay's contact would actuate a
device. Mayeb there is there *simple* modern equivalent of the
realy which can be used if I can't wire a sounder or a bulb
stright in?

 

[Palindr☻me]

I have a PIR-actived outdoor courtesy light. The PIR and the
lantern's lamp bulb are both inside the same single housing. This
runs off the mains (UK 240 volts). This is it:
http://www.focusdiy.co.uk/content/ebiz/focus/invt/23489/23489.jpg

I would like to modify this so that when the PIR detects something
then I get a notification inside the house. Perhaps from a beeper
or another lamp bulb.

-----

However I can only work with the mains supply because the PIR and
the lamp bulb are effectively one inseperable unit and also are
not easy to access.

Can I interrupt the 3 core mains supply to the lantern as a whole
and insert a device in SERIES (either in the neutral or in the
live lead)such that when the PIR fires and circuit is closed then
this device would actuate?

The impedance of the device woul dhave to be modest or it would
draw power from the PIR circuit and from the bulb circuit causing
both to potentially work wrongly.

Are there any device which would work in this setup? In the old
days maybe a relay would have been inserted in-line with one of
the mains supply wires and the relay's contact would actuate a
device. Mayeb there is there *simple* modern equivalent of the
realy which can be used if I can't wire a sounder or a bulb
stright in?

There are many, many approaches to this, depending on your competency
with electrics and electronics.

Replacing the fitting with one that does have the required
functionality, or adding one that does.

Modifying the "bell push" of a wireless door bell to detect that the
courtesy light has come on and operate the bell. eg a simple photoswitch.

Sensing the additional current that flows in the mains wire when the
lamp is on, using a Hall Effect device.

Sensing the additional current using a reed relay and surrounding coil
or a current transformer.

The first and last methods both require working with main wiring - you
may wish to Google search on "Part P regulations" and read the bit
about external power and lighting circuits.

However, I would suggest buying something like this:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=6050059179&category=41969

It's a cheap, wireless, pir-sensor alarm.

 

[Clive Mitchell]

I would like to modify this so that when the PIR detects something then
I get a notification inside the house. Perhaps from a beeper or
another lamp bulb.

Buy a new light/sensor with the remote warning facility. It will
probably be cheaper than spending lots of time trying to hack something
onto circuitry that is most likely referenced to mains voltage.

 

[Zak]

Buy a new light/sensor with the remote warning facility. It
will probably be cheaper than spending lots of time trying to
hack something onto circuitry that is most likely referenced to
mains voltage.

What you say seems tempting but unfortunately it is all installed now
and the mains lead to the lantern is the only thing which passes
indoors.

Fortunately it is near to my study/lounge.

 

[Zak]

There are many, many approaches to this, depending on your
competency with electrics and electronics.

Replacing the fitting with one that does have the required
functionality, or adding one that does.

Modifying the "bell push" of a wireless door bell to detect that
the courtesy light has come on and operate the bell. eg a simple
photoswitch.

Sensing the additional current that flows in the mains wire when
the lamp is on, using a Hall Effect device.

Sensing the additional current using a reed relay and
surrounding coil or a current transformer.

The first and last methods both require working with main wiring
- you may wish to Google search on "Part P regulations" and
read the bit about external power and lighting circuits.

However, I would suggest buying something like this:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=
6050059179&category=41969

It's a cheap, wireless, pir-sensor alarm.

I have one of those wireless sensor alarms. I find them useful. My
wireless sensor covers the very similar to the one in the lantern
(above) but they are mounted to face in different directions

However in this case I can not easily swap out the lantern and I do
not want to add yet another sensor.

The mains lead to the lantern is the only thing which passes indoors
and fortunately it passes close to my study/lounge where I tend to
be.

The wiring regs don't concern me overly as I yemd to live in the past
pre-home regs days! But actually it's ok because I am competent with
mains.

The Hall Effect sensors I looked up seem to be 6 to 24 volt. So a
power supply is needed to either run a 12 volt sounder or to runa
circuit which switches at mains voltage. Leaving yet another a power
supply brick on in the house does not appeal.

So maybe its the reed relay but Farnell does not stock a coil for
mains use. Their max is 80 volts: http://tinyurl.com/k38r2

:-(

 

[Palindr☻me]

What you say seems tempting but unfortunately it is all installed now
and the mains lead to the lantern is the only thing which passes
indoors.

Fortunately it is near to my study/lounge.

There are pir porch lamps with wireless annunciators. Changing one lamp
fitting for another is not that onerous - Part P permitting.

Otherwise, if you are determined to try to sense the extra current with
the light on, have a look at Hall Effect devices. It would be possible
to make something that just had to be taped to the (insulated) mains cable.

Farnell are a good source, now that Maplins has become MapHambly's Toy
Shop..

 

[Zak]

There are pir porch lamps with wireless annunciators. Changing
one lamp fitting for another is not that onerous - Part P
permitting.

Otherwise, if you are determined to try to sense the extra
current with the light on, have a look at Hall Effect devices.
It would be possible to make something that just had to be taped
to the (insulated) mains cable.

Farnell are a good source, now that Maplins has become
MapHambly's Toy Shop..

By chance I posted to you just a short while ago in other part of
this thread where I mention Farnell's stock. Q.V.

 

[Palindr☻me]

I have one of those wireless sensor alarms. I find them useful. My
wireless sensor covers the very similar to the one in the lantern
(above) but they are mounted to face in different directions

However in this case I can not easily swap out the lantern and I do
not want to add yet another sensor.

The mains lead to the lantern is the only thing which passes indoors
and fortunately it passes close to my study/lounge where I tend to
be.

The wiring regs don't concern me overly as I yemd to live in the past
pre-home regs days! But actually it's ok because I am competent with
mains.

The Hall Effect sensors I looked up seem to be 6 to 24 volt. So a
power supply is needed to either run a 12 volt sounder or to runa
circuit which switches at mains voltage. Leaving yet another a power
supply brick on in the house does not appeal.

So maybe its the reed relay but Farnell does not stock a coil for
mains use. Their max is 80 volts: http://tinyurl.com/k38r2

:-(

Look, I don't think any engineer here is going to tell you how to do it
by any way that requires direct connection to the mains supply and
doesn't require an external, low voltage supply. Quite simply, no one
wants an electrocution or burnt-down house on their conscience.

The reed relay approach would need such a connection, so I cannot help
you with it.

Sorry I can't help further

Sue

 

[Jamie]

I have a PIR-actived outdoor courtesy light. The PIR and the
lantern's lamp bulb are both inside the same single housing. This
runs off the mains (UK 240 volts). This is it:
http://www.focusdiy.co.uk/content/ebiz/focus/invt/23489/23489.jpg

I would like to modify this so that when the PIR detects something
then I get a notification inside the house. Perhaps from a beeper
or another lamp bulb.

-----

However I can only work with the mains supply because the PIR and
the lamp bulb are effectively one inseperable unit and also are
not easy to access.

Can I interrupt the 3 core mains supply to the lantern as a whole
and insert a device in SERIES (either in the neutral or in the
live lead)such that when the PIR fires and circuit is closed then
this device would actuate?

The impedance of the device woul dhave to be modest or it would
draw power from the PIR circuit and from the bulb circuit causing
both to potentially work wrongly.

Are there any device which would work in this setup? In the old
days maybe a relay would have been inserted in-line with one of
the mains supply wires and the relay's contact would actuate a
device. Mayeb there is there *simple* modern equivalent of the
realy which can be used if I can't wire a sounder or a bulb
stright in?

yes, a CT, (current transformer) then a comparator circuit to
trip on a current set point.

 

[Clive Mitchell]

yes, a CT, (current transformer) then a comparator circuit to
trip on a current set point.

Although quite frankly, once you've messed about with current
transformers and other associated buffering electronics, you'd probably
have saved many hours of your time and plenty of cash just by swapping
out the external sensor for an RF one.

Of course, you might just be doing this from a recreational perspective.

 

[Graham W]

yes, a CT, (current transformer) then a comparator circuit to
trip on a current set point.

Complicated!

What I did was to find an octal plugin relay whose coil current was
close to the demand of the PIR unit when the lamp was lit. This will
be a low voltage AC coil type or use a bridge rectifier for a DC coil.

The screw terminal plug-in base is easy to mount. Does the job
wonderfully!

Break the AC feed and measure the current then insert the coil
of a suitable relay in series with two ends. The AC feed can be used
directly through the relay contacts to activate a lamp or mains
buzzer etc.

 

[Palindr☻me]

Complicated!

What I did was to find an octal plugin relay whose coil current was
close to the demand of the PIR unit when the lamp was lit. This will
be a low voltage AC coil type or use a bridge rectifier for a DC coil.

The screw terminal plug-in base is easy to mount. Does the job
wonderfully!

Break the AC feed and measure the current then insert the coil
of a suitable relay in series with two ends. The AC feed can be used
directly through the relay contacts to activate a lamp or mains
buzzer etc.

Unfortunately, if the lamp or lamp fitting is changed to one with a high
efficiency, low wattage lamp, the relay will no longer operate. Worse,
if a higher wattage lamp is used, the relay coil will be absorb excess
power, with the possibility of fire. A zener diode of adequate wattage,
across the coil would be an improvement, as would fitting a capacitor to
reduce relay chatter (assuming the bridge rectifier is used, in both
cases). At the very least the protection (eg fusing) for this circuit
would need to be calculated and downrated. It is always possible that
the person implementing this alarm could be run over by a bus and the
new owner assume that the circuit is safe and standard.

The low voltage relay (say a 3v relay) coil insulation may not be rated
for peak 240 volt mains ac. Thus risking the possibility of insulation
breakdown, fire, electric shock, etc.

If wired into the live conductor, the whole circuit will be live. If
wired into the neutral, the remainder of the lamp circuit will become
live if the relay is unplugged or failed.

There are much better ways of implementing this safely.

 

[Long Ranger]

Complicated!

What I did was to find an octal plugin relay whose coil current was
close to the demand of the PIR unit when the lamp was lit. This will
be a low voltage AC coil type or use a bridge rectifier for a DC coil.

The screw terminal plug-in base is easy to mount. Does the job
wonderfully!

Break the AC feed and measure the current then insert the coil
of a suitable relay in series with two ends. The AC feed can be used
directly through the relay contacts to activate a lamp or mains
buzzer etc.

There are numerous small adjustable current relays out there.

 

[Jamie]

Unfortunately, if the lamp or lamp fitting is changed to one with a high
efficiency, low wattage lamp, the relay will no longer operate. Worse,
if a higher wattage lamp is used, the relay coil will be absorb excess
power, with the possibility of fire. A zener diode of adequate wattage,
across the coil would be an improvement, as would fitting a capacitor to
reduce relay chatter (assuming the bridge rectifier is used, in both
cases). At the very least the protection (eg fusing) for this circuit
would need to be calculated and downrated. It is always possible that
the person implementing this alarm could be run over by a bus and the
new owner assume that the circuit is safe and standard.

The low voltage relay (say a 3v relay) coil insulation may not be rated
for peak 240 volt mains ac. Thus risking the possibility of insulation
breakdown, fire, electric shock, etc.

If wired into the live conductor, the whole circuit will be live. If
wired into the neutral, the remainder of the lamp circuit will become
live if the relay is unplugged or failed.

There are much better ways of implementing this safely.

Yeah, as i said, a CT with Comparator sensing.
the CT will act as isolation, the comparator will
simply obsorb any over shots.

 

[[email protected]]

I would like to modify this so that when the [outdoor] PIR detects
something then I get a notification inside the house. [...]
Can I interrupt the 3 core mains supply to the lantern as a whole
and insert a device in SERIES (either in the neutral or in the
live lead)such that when the PIR fires and circuit is closed then
this device would actuate?

At one time you used to be able to get "smart" power strips that would
do this. You would plug the strip into the wall, and plug one device
into a marked socket on the strip. Then, when you turned on that
device, the strip would turn on all the other outlets on the strip.

15 years ago, they were sold for computers; you'd plug the computer into
the marked outlet and when you turned it on, your monitor and printer
would come on also. More recently, they have been sold as an accessory
for workshop dust collection systems; you plug your saw into the marked
outlet and when you start the saw, the power strip turns on the vacuum
motor. This is where I'd look if I wanted to buy one today.

What you'd have to do is cut the cable going to the outdoor fixture and
install a normal plug on the lantern end and a normal outlet on the
supply end. Then plug the power strip into the new outlet, and the new
plug into the marked outlet on the power strip. Then you would plug in
a lamp or buzzer or whatever into one of the switched outlets on the
power strip.

I have no idea if any of the above is acceptable under the UK wiring
regulations, so proceed at your own risk.

If the layout of the house allows, you can do this with no wiring at
all. Get some small mirrors and mount them on brackets to the outside
of the house, such that when the lantern comes on, the light is
reflected through a window in an eye-catching way.

Matt Roberds