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Need advice on best sensory only pick up human movement? Answered


Can anyone please point me in the right direction as to where can find a specific sensor as follows :
The sensor must cut the power to a multi plug 220v when someone comes within 2cm of where the sensor is placed. Only human interface is needed, anything other than human interface with the sensor must have no affect.

Secondly, I need to have a 12v solenoid activate immediately when the power is cut to the multi plug.

Is there anything out there that is reasonably inexpensive  that possibly performs both tasks and where can i find something like that, alternatively if someone has plans for a diy solution, that would be awesome.

Thanks in advance for any help :)




6 months ago

There is a simple (low cost) circuit that compares magnetically the current entering a receptacle and the current going leaving.. This is able to detect a difference in the tens of microamperes while 25 amperes are flowing..

This item available at most hardware stores and takes place inside the electrical outlet and needs no separate battery or PS..

The principle is that any difference current, could be flowing current through the child or errant adult and the power is cut off by a dual relay contact... Preventing injury !!

It appears to be some sort of permissive. If one is concerned about someone sticking their fingers (or someothing else) into a power receptacle, then a more sensible approach is the lock them out by encasing the receptacle in a tamper proof enclosure, ie a lockbox. There's a common rule in engineering that goes by the acronym KISS. Look it up if you aren't familiar. All you're trying to do is to prevent someone from electrocuting themselves. So deny them entry to the receptacle.

No simple DIY method to separate hum,ans from other animals. Body temperature, heart beat speed might work. Visual recognition by camera would perhaps be the best but not really DIY.

You can cut out may animals by making the detection point high up, however theis also cuts out children.

A larger capacitive sensor as for example often used on the poles of traffic light (for the pedestrians)...
They can be set for s distance between 1mm and a few cm.
Available in both 12/24V and mains power.

Simple add a relay and one contact opens to cut the power while you can use another to give a status signal.

But will it differentiate an orangutan or gorilla ;-)

At least not the tin man or pinoccio ;)


6 months ago

The only low cost way to differentiate between mammals is through a tiny RF implant found in stores to secure merchandise and has been used as security for individuals...

Otherwise you will have to use biometrics and that gets interestingly complex very rapidly...

Oh yea, once a detect signal is active, cutting 220 Volt power followed by

12V solenoid is relatively simple lots of ways to do it with discreet components or a tiny uP...