Adding extra device to all-in-one PIR lantern

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:

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

--
Sue

In message , Zak writes

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.

--
Clive Mitchell
http://www.bigclive.com

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.

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:

:-(

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..

--
Sue

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.

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

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

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

In message , Jamie writes

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.

--
Clive Mitchell
http://www.bigclive.com

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.

--
Graham W   http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE   http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK  Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.

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.

--
Sue

There are numerous small adjustable current relays out there.

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

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

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