Live wire sensor
Live wire sensor
(OP)
Just out of idle curiosity.
How does a domestic live wire detector sense AC live wires without coming into contact, when there is no current in live wire to induce current in sensor.
The AC potential alone must generate a field that sensor detects when it is close to conductor, but how?
Thanks in advance.
How does a domestic live wire detector sense AC live wires without coming into contact, when there is no current in live wire to induce current in sensor.
The AC potential alone must generate a field that sensor detects when it is close to conductor, but how?
Thanks in advance.





RE: Live wire sensor
We once designed a little telephone answerer that checked if there was voltage on the grid and what temperature you had in the leisure cottage. Plus a few switches.
We had a problem with the voltage supervision until we found out that a few feet of wire along any mains cord picked up enough stray voltage to activate a standard CMOS gate. Worked like a dream. And we never had to attach the box to the grid.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Live wire sensor
Gunnar,
OK, you've stumped me.
You detect line voltage and cottage (ambient?) temperature and decide whether or not to answer a telephone. I'm not sure why anybody would want to do that, so I'm curious why and what the truth table looks like
voltage + low temp = answer or no answer
voltage + high temp =
low/no voltage + high temp =
high voltage + low temp =
Dan
RE: Live wire sensor
These little houses often have running water installed, some have freezers and all have windows. Many guys go to their little houses just to see if everything is OK and then back home again. Distances are sometimes 500 km (300 miles) one way and it is both time-consuming and expensive to do such an "inspection trip" so many don't do it. Only to find out that a snow storm or lightning or burglars have hit the house so that water pipes have frozen or that elk, bear, reindeer, trout or salmon meat in the freezer has gone bad.
So, we designed a little battery thing that checks if basic things like mains voltage, temperatures, windows and doors are OK. It is called "Stugvakten", which means "Cottage Guard". Battery life is around five years (three AA cells). We were contemplating marketing it in Russia. Name "Datja-Safe". But not done that yet. You phone it and it answers with simple tone codes.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Live wire sensor
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Keith Cress
kcress - http://www.flaminsystems.com