Looking for a proximity sensor setup

[Frenchy]

I am looking for some sort of proximity sensor setup that would operate within a range of a few feet. Basically I would like something that would operate a switch to send power to a component when a fob of some sort is within range. I don't want something that would need a button to be pushed, just something that operates automatically when it's within the range of maybe 5 feet or less. Anyone able to steer me in the right direction to find something like this? Thanks in advance

 

[EPAIII]

Wifi has a fairly short range. But more than five feet. And any battery powered device would have a variable output as the battery drains. It could use a Voltage regulator, but that may have an abrupt cutoff when the battery gets too low.

And what is the environment like? Objects in the way could attenuate the signal.

I wonder if an attenuated garage door opener might do it. Add a Voltage regulator to the remote and use a big battery and change it often enough so it doesn't die. A resistive attenuator could be added between the transmitter chip and the antenna.

But it may not be legal to use a garage door opener like this.

If line of sight is guaranteed, something optical or infra-red may work.

Or perhaps something that uses ultrasound. A frequency above the limit of human hearing. Sound can wrap around most obstacles. Modulate it with a code to prevent false triggering when someone blows a dog whistle or something. The base station could transmit constantly while the remote listens for it and only responds when it is close. That would save on battery life if the base station could use AC power.

Just spit-balling here.

How reliable does this need to be? You are probably going to need to share more details to get a decent answer.

Oh wait, what about those electronic dog fences? The ones where the dog gets a shock when he gets too close to the fence wire.

 

[LockNut]

Keyence will have somethiong like this.

https://www.keyence.com/products/sensor/

 

[MwTech Inc]

automation direct
happy customer

 

[rons]

I am looking for some sort of proximity sensor setup that would operate within a range of a few feet. Basically I would like something that would operate a switch to send power to a component when a fob of some sort is within range. I don't want something that would need a button to be pushed, just something that operates automatically when it's within the range of maybe 5 feet or less. Anyone able to steer me in the right direction to find something like this? Thanks in advance

Are you asking about this with the word "range" being a radius about a central point? Like the front porch light variety.
The Keyence stuff I have seen in the past is just beam interruption/detection or single point proximity.

 

[Frenchy]

Thanks for the responses so far. I'm sorry it's a bit OT so I didn't mention the application but it would help to understand what I'm looking for.

I was hoping to make a dog door that has a lock that only opens when the dog is close to it. They sell some like this that are triggered by a small fob on the dog's collar but they open automatically and stay open for several seconds before closing. I want one that still needs to be pushed open by the dog but has a pin that locks it when the dog isn't near it.

My issue with the auto opening ones is that the wife's favorite cat would figure out pretty quickly that the door stays open a few seconds after the dog goes out and he would end up being coyote food pretty quickly. Cats need to be hard asses in these parts to survive all of the coyotes and bobcats and ours is a soft indoor cat who wouldn't stand a chance.

Any ideas on a simple setup for this? The only thought I had was to buy the auto opening one and modify it.

 

[TeachMePlease]

NFC is what you want, I think. Cheap readers/writers are available for people who hack arduino stuff, so you should be able to find parts easily.
Double check me of course, but I think it'd do what you want.

 

[rons]

It wouldn't be so hard to get a outdoor light/sensor from a big box store and wire the output to a timer in one-shot mode.
It would enable/disable a simple door lock like the ones used in 2-3 story apartments. I use one on my front door and when
activated in "open" mode the the device buzzes. Your dog could learn to walk in when the thing makes a buzz.

A lady cat owner told me that the average life of an outdoor cat is 2 years.

 

[MwTech Inc]

Automation direct Click plc.....lol
Actually, would be pretty cool to use one, base unit has ample in/out contacts for your use.
Free software to program...easy

 

[JPD]

What about the clapper?

 

[MrStretch]

Extra points for making a door with rfid reader that only works with the dog. Your dog probably already has a chip and each chip has its own unique number.

 

[MwTech Inc]

Op needs a 'Woofer"....

 

[Frenchy]

NFC is what you want, I think. Cheap readers/writers are available for people who hack arduino stuff, so you should be able to find parts easily.
Double check me of course, but I think it'd do what you want.

I'll have to look into this. This seems like the sort of thing I'm looking for.

 

[Frenchy]

Automation direct Click plc.....lol
Actually, would be pretty cool to use one, base unit has ample in/out contacts for your use.
Free software to program...easy

Is this something that could be set up with a NFC sensor? I'm fairly useless when it comes to electronics. Wish my electrical engineer dad was still around.

 

[MwTech Inc]

Is this something that could be set up with a NFC sensor?

if the NFC sensor has an output, then the PLC would accept that and then do the required output function
In simple terms...lol

 

[Frenchy]

if the NFC sensor has an output, then the PLC would accept that and then do the required output function
In simple terms...lol

Sounds like a good starting point. I'll have to do my homework and see if I can figure something out. Thanks

 

[animal12]

Sounds like that could be done with a Arduino or a Raspberry Pi if ya know anyone that can do the code . Ya could have different sensors for the cat & dog
animal

 

[Erich]

A long time ago I read about a guy who did facial recognition to unlock his cat door. His cat, door unlocks.
Possum or dog, no open.
His cat with dead animal in mouth, no open.
This was over 20 years ago, so this should be trivial today.

 

[blcksmth]

I don't know what technology is used in key less automobiles that detect when the owner, with the keys, gets close and then unlocks the doors and allows the starter.

Bob
WB8NQW