I reckon I could put a reed switch ( www.explainthatstuff.com/howreedswitcheswork.html ) against L1 and L2 wire and somehow rectify the small magnetic field that is given there when L1 or L2 has current flowing through it. Anyone know if this would work ?
Hallway lights with switch at either end of hallway and PIR
- Thread starter kez1
- Start date
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Fairly sure a reed switch will not activate from the magnetic field around a cable - they usually need a magnet.
What about a Hall effect sensor ? Will the current change enough in L1 or L2 when a portion of the current goes down there, when closed, to activate a Hall effect device ?
No it won't The magnetic field from the current in the wire will be far too small. The sensitivity of a reed switch is measured in amp turns when being operated by current in a coil. At least 10 to 20 amp turns are needed for small reed switchs.
1 amp in 20 turns or 20 amps in one turn are the same.
http://en.wikipedia.org/wiki/Reed_switch
Also the mains current is AC so the magnetic field will be changing direction 50 times a second and the contact would be trying to follow that.
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Folks
Thank you for all your replies.
PIR's fitted to the house have been a godsend.
I now know how much time I spent over the years (wasted) fiddling with hall landing switches.
I think the solution is going to be something like a rectifier and a reed switch or a hall effect sensor. When I get a solution I will post it up.
Thank you
Ke z
Thank you for all your replies.
PIR's fitted to the house have been a godsend.
I now know how much time I spent over the years (wasted) fiddling with hall landing switches.
I think the solution is going to be something like a rectifier and a reed switch or a hall effect sensor. When I get a solution I will post it up.
Thank you
Ke z
I have never encountered any that would not be an utter PITA to live with. And look at the complications this one is introducing - it's created a problem which simply would not exist if you did not have it.
And all because you can't be rsed to use a switch:
You switch them on and off as necessary - where's the fiddling in that?
Your problem is interfacing the PIR with the manual switches and being able to tell whether the light is on due to the PIR or the manual switches.
Without having an indicator lamp to indicate that the manual switches are in the ON state you will not be able to know whether it is the PIR or the manual switches or both that have turned the lights on.
As you want to solve it your self here is a hint.
Two intermediate switches can be wired up to produce a change over function that will turn either the lamps ON or a small indicator ON when the main lamps are OFF. Then if the lamps are ON and the indicator is also ON then you will know the PIR is ON and the manual switches are OFF and that the lamps will go OFF when the PIR times out.
Without having an indicator lamp to indicate that the manual switches are in the ON state you will not be able to know whether it is the PIR or the manual switches or both that have turned the lights on.
As you want to solve it your self here is a hint.
Two intermediate switches can be wired up to produce a change over function that will turn either the lamps ON or a small indicator ON when the main lamps are OFF. Then if the lamps are ON and the indicator is also ON then you will know the PIR is ON and the manual switches are OFF and that the lamps will go OFF when the PIR times out.
Funny - I could have sworn this site was about Do It Yourself, not Ask Someone Else To Do It Because You Don't Want To.
Or Plan C - get rid of the switches and just have the PIR, then you won't have to worry about the light not turning off because a switch is on.
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Well....it is DIYnot........
What would you do if the lights weren't in the hall?
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