Hello all,

I want to build a door sensor that indicates when the door and window is LOCKED or UNLOCKED, and sends a simple "ON" or "OFF" signal to a receiver, which could then decode the signal (or simply repeat it, as I assume it is just a case of "high" and "low").
The simplest and smallest way that found for this to be done would be to put a reed switch on the wall bordering the door/window, and a small magnet embedded on the lock to activate the switch when closed.
This seems straight-forward, but I would like to know how to then transmit this "ON" signal wirelessly.
I have no idea how to approach this, as all the amateur projects I've done were simple and on breadboards, but I now have time to actually study electronics.
Therefore, I would like to know if you have recommendations of text-books and topics that I can study to learn how to thoroughly understand wireless data transmission, and how to build from scratch a transmitter and receiver for this simple project.

Thanks in advance!

 

Your biggest problem will be some kind of sensor that will sense when the lock is in a locked or unlocked state.
If you give some details of the locks we may be able to suggest a suitable type of sensor. What is the required distance between the transmitter and receiver ? If your window locks are like ours the locked/unlocked state will be quite difficult to detect.
Les.

 

Your biggest problem will be some kind of sensor that will sense when the lock is in a locked or unlocked state.
If you give some details of the locks we may be able to suggest a suitable type of sensor. What is the required distance between the transmitter and receiver ? If your window locks are like ours the locked/unlocked state will be quite difficult to detect.
Les.

EDIT: Edited because I forgot to answer the distance question.

Thank you for the reply.

The distance between receiver and transmitter would be no larger than 10 meters.

I will put a couple of examples of the locks below.



For this sensor, wouldn't an embedded but superficial reed switch on the frame, aligned with the lock bolt with an embedded magnet (I would drill the bolt to glue a magnet in it) be enough to close a circuit and indicate the "LOCKED" status?

Barbpp

 

How will the transmitter be powered?
If you build it from scratch, how will you know if its transmission frequency and strength are legal?
What test equipment do you have?
Do you have soldering skills?

 

How will the transmitter be powered?
If you build it from scratch, how will you know if its transmission frequency and strength are legal?
What test equipment do you have?
Do you have soldering skills?

Ideally, it would be powered by the mains of the house. But this is much further in the future. I would like to make a simple proof of concept first.

Regarding frequency and strength, given that this is just a proof of concept project, I wouldn't expect it to be a problem. It would be like learning things in a school setting with simple parts.

Regarding equipment, I have access to an oscilloscope, a frequency generator and a power supply that I've used for simple projects on breadboards.

Regarding soldering skills, I have never done it. I have just used breadboards.

That is why I wish to get recommendations on textbooks to learn about this, and progressively learn the skills to eventually build the proof of concept.

 

Hello all,

I want to build a door sensor that indicates when the door and window is LOCKED or UNLOCKED, and sends a simple "ON" or "OFF" signal to a receiver, which could then decode the signal (or simply repeat it, as I assume it is just a case of "high" and "low").
The simplest and smallest way that found for this to be done would be to put a reed switch on the wall bordering the door/window, and a small magnet embedded on the lock to activate the switch when closed.
This seems straight-forward, but I would like to know how to then transmit this "ON" signal wirelessly.
I have no idea how to approach this, as all the amateur projects I've done were simple and on breadboards, but I now have time to actually study electronics.
Therefore, I would like to know if you have recommendations of text-books and topics that I can study to learn how to thoroughly understand wireless data transmission, and how to build from scratch a transmitter and receiver for this simple project.

Thanks in advance!

Use a magnet on the window, and a hall-effect sensor on the frame. Use an off the shelf TTL/UART -> Wireless adapter (a little PCB, ready made for this) rather than tackle that yourself. The has the benefit of being more reliable- It's based on window movement.

Go to Amazon, and search for this ASIN: B0DCJ8PM4K

 

To avoid having to sending a continuous signal you could send a signal say every 5 seconds. as you need to send the state of 2 sets of contacts that would have 4 possible states. You could use these 4 states to simulate pressing one of 4 buttons on a 4 channel remote control relay such as this. https://www.ebay.co.uk/itm/324274753685.
You could then configure the receiver part to behave in a 2 channel on/off mode to show the state of the two alarm contacts.
Les.

 

Thank you all for your suggestions.
I will use them to focus my studies on how each of them works.