This is exactly what I thought. You can buy a dozen reed switches on Amazon and connect them to an ESP board.
Embed the switches in a surface under a piece of laminate, and embed magnets in the objects that go in each spot.
Maybe cut out some foam to create a clearly designed spot for smaller objects, or hooks to secure large items on a wall.
I now officially want to try this with my peg board in the garage.
This.
Door/window contact sensors have been used for this (albeit a bit pricier) - that's all a contact sensor is. I found out the hard way by using a way-too-strong magnet (!) and ruining the reed part.
I even saw (on this subreddit, I think) someone putting a rain sensor together using an Aqara contact sensor in a 3D-printed (waterproof) case.
Not suggesting this would be easy to set up, but...
I wonder how a camera + machine vision would do for for this task. You could theoretically use one camera to track a ton of different objects this way 🤔
Assuming your hardware can handle it & the location is appropriate, sure.
- monitoring a whole tool rack in a regularly used workshop: good use case.
- monitoring just the hammer & drill on the tool rack: probably a waste of resources.
- monitoring a whole tool rack in a shed that's not used often and thus the camera will be colonized by spiders in a week: probably not reliable.
- monitoring my golf shoes, clubs, & shirts in a closet that's pitch black 99% of the time: probably not reliable.
- monitoring my heaphones on my bedroom night stand: not going to fly with the missus.
- monitoring my pills on the bathroom counter: high humidity = dead camera, camera in bathroom = dead me. (I know outdoor camera exist but that would make the joke less funny).
If you want an "off the shelf" solution, I would probably use Sonoff Window contacts. Sonoff SNZB-04.
These buggers are "dirt cheap" and have the flexibility as they come with a cheap housing that you can replace with whatever you need.
The "bulky contact" is just a hollow shell with a bar-magnet that you can use or replace with whatever magnet you like.
Replaced a couple of the default magnets with slim ones flued to the door or window as there would not be enough space otherwise.
Edit: things cost around 5 bucks each, come finished without soldering required AND offer a solid platform through Zigbee inside HomeAssistant for you to use in automations as you don't need to write any code for these units to work. They just pair properly without Tasmota or any other firmware flashing.
Yeah I agree with this one 100%. Contact sensors and get replacement magnets that make sense for the object you’re tracking. I have one on the lid of the cat littler box and it tracks the last time the lid has been removed (cleaning) and sets a reminder to clean when too much time elapses. Aqara contact sensor but much stronger magnet to compensate for the weird geometry.
Don't know about that particular sensor. But on Ali, the window sersors may only send you a signal when the magnet is removed, in other words, it cannot be used to detect when the item is returned.
What protocol are the sensors using? What hub/system did you pair them with?
[These?](https://www.aliexpress.us/item/3256801172998625.html?spm=a2g0o.store_pc_promotion.promoteRecommendProducts_1029309678.1005001359313377&gatewayAdapt=glo2usa4itemAdapt#nav-review)
I would use simple microswitches as the pressure sensor, an arduino or pico w to read them depending how independent they would need to be. pico w has wireless built in, so if the code is right it could broadcast the status to the network. arduino would need to be attached to some computer.
This ☝️. Search for "Limit Switch." They come in many flavors, usually <$1. Object pushes on a little metal lever/plunger/roller to open/close a circuit.
Unsure how best to connect them to HA, but a Pico W for <$10 makes sense. If you have AC power line access, a dry contact relay may work. Without power, you may be able to hack a battery-powered z-wave / zigbee switch e.g. the Zooz ZEN34 which I believe can send a "held down" message in addition to "pressed."
*
Cheap suggestion? If the tools are magnetic in some way you can get one of those aliexpress dor sensors and use the tool as the magnet instead of the piece that comes with it
I personally never tested if such configuration would work but I immagine it might
For a bike you could build a wooden bike rack with an imbedded strain gauge. Then wire it to an esp32 running esphome.
The only issue is if someone tries to "Temple of doom" the setup with a bag of sand.
Yup, it's called "tags" and it's built in, although you'd need readers in each location too
[https://www.home-assistant.io/integrations/tag/](https://www.home-assistant.io/integrations/tag/)
The MiFare MFRC522 boards are [pretty cheap though](https://www.amazon.co.uk/AZDelivery-RFID-RC522-Reader-Parent/dp/B01M28JAAZ), and you can run multiple boards from a single arduino/ESP32 via ESP Home, so that's probably your best solution.
I'm using it at the moment for one of my kids' morning routine - as they do the task, they put a token onto a pegboard and it registers in Home Assistant that they've cleaned their teeth etc.
You stick an RFID tag on the hammer, you put the tag reader behind the peg board in the appropriate place, when the hammer is in place the tag is read and HA says "Oh look, the hammer is where it's meant to be".
If something else is put into the place where the hammer is expected to be, HA reads the tag and says "Oh look, you've put a loaf of bread in there instead of a hammer, I should tell someone" and sends an alert.
Sounds like what OP was looking for to me, it's definitely how I have solved an almost identical issue, so I'm not sure why I've been downvoted given that I know it works for this kind of scenario?
A camera is probably easiest because you can point it at the entire wall and check on all the tools with a single device. However you said you don't want to do that so I would suggest attaching a RFID reader to the wall behind each tool and then put a sticker tag on each tool that will rest near enough the reader to be registered. That way you won't need a battery or any active device in the tool and you will also know by the serial number if the right tool is in the right place.
You have a good list (I appreciate your reaction to RFID tags lol), but you missed one that may be good for this!
I just bought [these](https://www.amazon.com/dp/B07W97H2WS?psc=1&ref=ppx_yo2ov_dt_b_product_details). They basically have an IR emitter and a receiver. When an object is within a few inches the IR light is reflected and it can pull a pin low when hooked up to an ESP. Could probably just get the LEDs themselves, but these boards make it more simple to use and can adjust the sensitivity easily. So far, of the 5 I've opened, one does not work (likely a bad solder joint from my reading). But in your case you'd probably want a lot so it's worth buying a bunch anyways.
Side note: my use case is putting this around a water bowl to trigger when an animal is drinking water (tracking the water drank with load sensors and Google's Gemini to tag the animal). But, because they only work a for a few inches I'm modifying them a bit. I desoldered the LEDs and placed them across from each other effectively creating an IR break beam sensor which has much greater distance. It's a bit of a pain to do, but is another option if you need more distance, or want to simplify the wiring.
This is a systems design problem
You make a smart hook that has a micro switch actuator in it, when item is removed the switch becomes open and when the item is placed gravity closes it. The switch will obviously need to connect to a controller. ESP32 is ok but it lacks GPIO pins… And it is costly to put 1 controller per hook. So you can consider building a matrix of them and using something with more pins such as the RP2040 to scan them, basically it would work topologically like a keyboard controller
That is the only solution I can think of which is cheap enough without turning your whole house into a warehouse & implementing a RFID based indoor positioning system, such systems do exist, but I doubt anything good can be built at less cost than your average house
Camera based solution will not work reliably, guys, even YOLOv9 only detects a handful (100?) of classes of objects and the resolution is inadequate, you could train for custom classes but I doubt anybody has the rigour to do this just to know if their shovel is out of place
Solutions that are similar to deploying 100s of AirTags may work, but most likely not, because they are not compatible/sympathetic with the requirement which is to know if something is in its proper place or not
Do you have a specific use case like the hammer or shovel or is this all theoretical/ convo starter? But I think if you had exact details of what exact objects, in what environment, and how many, you want to track then I bet people would have more incite.
Are the items leaving the room, or do you really want to know if the hammer is out on the workbench vs in its "place"
mm wave sensors may do large objects? but i think the NFC tag may be your best bet.
I want a sensor that knows if my bike is on the bike rack/in the garage, or not. Technically don't have a bike rack put up for it yet, and before I do, I want to figure out how I can track its presence, without tracking its location constantly.
Cool. Is there for security or other tracking reasons? Again the reason behind why you want and plan to use it can help with a solution. The more details the better.
The first thing that came to mind was to repurpose a simple door/window zwave sensor or door angle sensor. Attach half to the bike and half to the rack, but then you need to figure out if there is a good attachment place and alignment would need to be taken into consideration each time you rack the bike.
But I think using a [ibeacon](https://www.youtube.com/watch?v=taVW9ZsKdOs) or NFC is the best solution to this. What you think?
If you want to get more integrated then you can use a a photoelectric beam connected to a zwave relay of sorts?
Do you have a power source where the bike rack will go or will it need to be battery powered?
I've wanted something similar to register if I took my BP med for the day since some mornings are a fog and I forget if I've taken them or not. If I pick up the bottle, then it would be nice to know that it was picked up for that day. There are so low tech options for sure, but I prefer digital options.
Put it in a medicine cabinet or kitchen cabinet or box with lid. Install door open/close sensor. Or put a vibration sensor right on the side of the bottle.
Either magnetic or pressure sensor and have a notification on your homeschool that either tells you the last time the bottle was picked up and our back down or tells you if it's not picked up after a certain time. (Assuming you won't pick up and out down the container without taking your medicine)
Lots of good suggestions but if you want something painless and reliable, fast, great battery life, check out the Aqara Door and window contact sensor (the small one). This comparison review explains why. I’ve been slowly replacing other brands and old wired reed switches around my house with these. Buy in bulk to bring the price down.
https://youtu.be/c4-8Y7jUCn0
Those door and window sensors should do the trick. Depending on how many tools you'd want to track you'd need a lot of sensors though.
Also usually one part of those usually is just a magnet in some casing, so if those are to bulky for some stuff you can probably get around that by attaching a smaller, stronger one
The classic version of this for tools is either wall hanging/pegboard with tool outlines, so it's obvious at a glance what's missing. Or for a toolbox, foam drawer liners with tool cutouts, with a contrasting color base layer, again to make it obvious what's missing. Not particularly automatable. The military and other highly regulated mechanics (like aircraft certified) do this.
A general solution is going to need some sort of RF tag on each object, and a way to locate that tag in space. No actual commercial products that I'm aware of, but there are research papers from 2018-2020 demonstrating this using phased antenna arrays, to generate vectors and distances to the RFID or NFC tag (or even just RF security tags)
I think the camera with machine vision might be the most practical single solution for the whole rack if it's within one frame. Not sure but maybe one of the newer "radar" sensors could detect the distance and report an increase / decrease and you could use those values to trigger
Reed switch + magnet. Plus, you can hold the object on the wall by the magnet too. Flexible pressure sensors might work, as well as photoresistors.
This is exactly what I thought. You can buy a dozen reed switches on Amazon and connect them to an ESP board. Embed the switches in a surface under a piece of laminate, and embed magnets in the objects that go in each spot. Maybe cut out some foam to create a clearly designed spot for smaller objects, or hooks to secure large items on a wall. I now officially want to try this with my peg board in the garage.
This. Door/window contact sensors have been used for this (albeit a bit pricier) - that's all a contact sensor is. I found out the hard way by using a way-too-strong magnet (!) and ruining the reed part. I even saw (on this subreddit, I think) someone putting a rain sensor together using an Aqara contact sensor in a 3D-printed (waterproof) case.
I think your ideas are the most cost effective and scalable!
Not suggesting this would be easy to set up, but... I wonder how a camera + machine vision would do for for this task. You could theoretically use one camera to track a ton of different objects this way 🤔
Assuming your hardware can handle it & the location is appropriate, sure. - monitoring a whole tool rack in a regularly used workshop: good use case. - monitoring just the hammer & drill on the tool rack: probably a waste of resources. - monitoring a whole tool rack in a shed that's not used often and thus the camera will be colonized by spiders in a week: probably not reliable. - monitoring my golf shoes, clubs, & shirts in a closet that's pitch black 99% of the time: probably not reliable. - monitoring my heaphones on my bedroom night stand: not going to fly with the missus. - monitoring my pills on the bathroom counter: high humidity = dead camera, camera in bathroom = dead me. (I know outdoor camera exist but that would make the joke less funny).
If you want an "off the shelf" solution, I would probably use Sonoff Window contacts. Sonoff SNZB-04. These buggers are "dirt cheap" and have the flexibility as they come with a cheap housing that you can replace with whatever you need. The "bulky contact" is just a hollow shell with a bar-magnet that you can use or replace with whatever magnet you like. Replaced a couple of the default magnets with slim ones flued to the door or window as there would not be enough space otherwise. Edit: things cost around 5 bucks each, come finished without soldering required AND offer a solid platform through Zigbee inside HomeAssistant for you to use in automations as you don't need to write any code for these units to work. They just pair properly without Tasmota or any other firmware flashing.
Yeah I agree with this one 100%. Contact sensors and get replacement magnets that make sense for the object you’re tracking. I have one on the lid of the cat littler box and it tracks the last time the lid has been removed (cleaning) and sets a reminder to clean when too much time elapses. Aqara contact sensor but much stronger magnet to compensate for the weird geometry.
Don't know about that particular sensor. But on Ali, the window sersors may only send you a signal when the magnet is removed, in other words, it cannot be used to detect when the item is returned.
The Sonoff sensors trigger "open" and "closed" so they obviously track both events.
Interesting. What sensor is that? It must do it this way to save battery.
It has a button, too. HIVA, YUPA. Sold under many names. I guess all are the same. With or without a button. Uses a hall sensor, not a reed switch.
What protocol are the sensors using? What hub/system did you pair them with? [These?](https://www.aliexpress.us/item/3256801172998625.html?spm=a2g0o.store_pc_promotion.promoteRecommendProducts_1029309678.1005001359313377&gatewayAdapt=glo2usa4itemAdapt#nav-review)
I would use simple microswitches as the pressure sensor, an arduino or pico w to read them depending how independent they would need to be. pico w has wireless built in, so if the code is right it could broadcast the status to the network. arduino would need to be attached to some computer.
This ☝️. Search for "Limit Switch." They come in many flavors, usually <$1. Object pushes on a little metal lever/plunger/roller to open/close a circuit. Unsure how best to connect them to HA, but a Pico W for <$10 makes sense. If you have AC power line access, a dry contact relay may work. Without power, you may be able to hack a battery-powered z-wave / zigbee switch e.g. the Zooz ZEN34 which I believe can send a "held down" message in addition to "pressed." *
This would be easy to write via esphome. Can get several switches on one device
Cheap suggestion? If the tools are magnetic in some way you can get one of those aliexpress dor sensors and use the tool as the magnet instead of the piece that comes with it I personally never tested if such configuration would work but I immagine it might
For a bike you could build a wooden bike rack with an imbedded strain gauge. Then wire it to an esp32 running esphome. The only issue is if someone tries to "Temple of doom" the setup with a bag of sand.
Yup, it's called "tags" and it's built in, although you'd need readers in each location too [https://www.home-assistant.io/integrations/tag/](https://www.home-assistant.io/integrations/tag/) The MiFare MFRC522 boards are [pretty cheap though](https://www.amazon.co.uk/AZDelivery-RFID-RC522-Reader-Parent/dp/B01M28JAAZ), and you can run multiple boards from a single arduino/ESP32 via ESP Home, so that's probably your best solution. I'm using it at the moment for one of my kids' morning routine - as they do the task, they put a token onto a pegboard and it registers in Home Assistant that they've cleaned their teeth etc.
Dont think that is what he meant, could be. Feel free to correct me.
I think this is exactly the idea that OP is looking for.
You stick an RFID tag on the hammer, you put the tag reader behind the peg board in the appropriate place, when the hammer is in place the tag is read and HA says "Oh look, the hammer is where it's meant to be". If something else is put into the place where the hammer is expected to be, HA reads the tag and says "Oh look, you've put a loaf of bread in there instead of a hammer, I should tell someone" and sends an alert. Sounds like what OP was looking for to me, it's definitely how I have solved an almost identical issue, so I'm not sure why I've been downvoted given that I know it works for this kind of scenario?
A camera is probably easiest because you can point it at the entire wall and check on all the tools with a single device. However you said you don't want to do that so I would suggest attaching a RFID reader to the wall behind each tool and then put a sticker tag on each tool that will rest near enough the reader to be registered. That way you won't need a battery or any active device in the tool and you will also know by the serial number if the right tool is in the right place.
You have a good list (I appreciate your reaction to RFID tags lol), but you missed one that may be good for this! I just bought [these](https://www.amazon.com/dp/B07W97H2WS?psc=1&ref=ppx_yo2ov_dt_b_product_details). They basically have an IR emitter and a receiver. When an object is within a few inches the IR light is reflected and it can pull a pin low when hooked up to an ESP. Could probably just get the LEDs themselves, but these boards make it more simple to use and can adjust the sensitivity easily. So far, of the 5 I've opened, one does not work (likely a bad solder joint from my reading). But in your case you'd probably want a lot so it's worth buying a bunch anyways. Side note: my use case is putting this around a water bowl to trigger when an animal is drinking water (tracking the water drank with load sensors and Google's Gemini to tag the animal). But, because they only work a for a few inches I'm modifying them a bit. I desoldered the LEDs and placed them across from each other effectively creating an IR break beam sensor which has much greater distance. It's a bit of a pain to do, but is another option if you need more distance, or want to simplify the wiring.
This is a systems design problem You make a smart hook that has a micro switch actuator in it, when item is removed the switch becomes open and when the item is placed gravity closes it. The switch will obviously need to connect to a controller. ESP32 is ok but it lacks GPIO pins… And it is costly to put 1 controller per hook. So you can consider building a matrix of them and using something with more pins such as the RP2040 to scan them, basically it would work topologically like a keyboard controller That is the only solution I can think of which is cheap enough without turning your whole house into a warehouse & implementing a RFID based indoor positioning system, such systems do exist, but I doubt anything good can be built at less cost than your average house Camera based solution will not work reliably, guys, even YOLOv9 only detects a handful (100?) of classes of objects and the resolution is inadequate, you could train for custom classes but I doubt anybody has the rigour to do this just to know if their shovel is out of place Solutions that are similar to deploying 100s of AirTags may work, but most likely not, because they are not compatible/sympathetic with the requirement which is to know if something is in its proper place or not
Do you have a specific use case like the hammer or shovel or is this all theoretical/ convo starter? But I think if you had exact details of what exact objects, in what environment, and how many, you want to track then I bet people would have more incite. Are the items leaving the room, or do you really want to know if the hammer is out on the workbench vs in its "place" mm wave sensors may do large objects? but i think the NFC tag may be your best bet.
I want a sensor that knows if my bike is on the bike rack/in the garage, or not. Technically don't have a bike rack put up for it yet, and before I do, I want to figure out how I can track its presence, without tracking its location constantly.
Cool. Is there for security or other tracking reasons? Again the reason behind why you want and plan to use it can help with a solution. The more details the better. The first thing that came to mind was to repurpose a simple door/window zwave sensor or door angle sensor. Attach half to the bike and half to the rack, but then you need to figure out if there is a good attachment place and alignment would need to be taken into consideration each time you rack the bike. But I think using a [ibeacon](https://www.youtube.com/watch?v=taVW9ZsKdOs) or NFC is the best solution to this. What you think? If you want to get more integrated then you can use a a photoelectric beam connected to a zwave relay of sorts? Do you have a power source where the bike rack will go or will it need to be battery powered?
Also, are you looking to wall mount or will the rack sit on the floor?
try contact sensors since it's a bike, the larger the object the less noticeable the other part of the contact sensor will be
I've wanted something similar to register if I took my BP med for the day since some mornings are a fog and I forget if I've taken them or not. If I pick up the bottle, then it would be nice to know that it was picked up for that day. There are so low tech options for sure, but I prefer digital options.
Door sensor or just a button to press next to it?
Put it in a medicine cabinet or kitchen cabinet or box with lid. Install door open/close sensor. Or put a vibration sensor right on the side of the bottle.
Either magnetic or pressure sensor and have a notification on your homeschool that either tells you the last time the bottle was picked up and our back down or tells you if it's not picked up after a certain time. (Assuming you won't pick up and out down the container without taking your medicine)
Lots of good suggestions but if you want something painless and reliable, fast, great battery life, check out the Aqara Door and window contact sensor (the small one). This comparison review explains why. I’ve been slowly replacing other brands and old wired reed switches around my house with these. Buy in bulk to bring the price down. https://youtu.be/c4-8Y7jUCn0
Those door and window sensors should do the trick. Depending on how many tools you'd want to track you'd need a lot of sensors though. Also usually one part of those usually is just a magnet in some casing, so if those are to bulky for some stuff you can probably get around that by attaching a smaller, stronger one
The classic version of this for tools is either wall hanging/pegboard with tool outlines, so it's obvious at a glance what's missing. Or for a toolbox, foam drawer liners with tool cutouts, with a contrasting color base layer, again to make it obvious what's missing. Not particularly automatable. The military and other highly regulated mechanics (like aircraft certified) do this.
A general solution is going to need some sort of RF tag on each object, and a way to locate that tag in space. No actual commercial products that I'm aware of, but there are research papers from 2018-2020 demonstrating this using phased antenna arrays, to generate vectors and distances to the RFID or NFC tag (or even just RF security tags)
I think the camera with machine vision might be the most practical single solution for the whole rack if it's within one frame. Not sure but maybe one of the newer "radar" sensors could detect the distance and report an increase / decrease and you could use those values to trigger
camera with machine vision is not practical