Standalone Wireless Transmitter

I am trying to make a prototype door sensor where a door stopper is activated when the door is opened and deactivated when the room key is present. This product would prevent people from having lock-outs.

1) I understand that there are XBee transmitters that could allow me to make my prototype. However, XBee transmitters have to be connected to Arduino Boards. This makes the transmitting device much bigger than the key itself.

Are there any standalone wireless transmitting device that does not have to be connected to an Arduino board and can communicate with a receiving device connected to an Arduino board on the door frame?

2) Are there magnetic sensors for Arduinos?

Many thanks!

My first thought would be RFID. Doing a google of arduino rfid gives this as one of the first links:

Transmitter receiver pairs:

Or Solarbotics for example:


Thanks for your prompt response! I was thinking about using an RFID tag too. However, RFID tags only have a very limited range. Are there any RFID tags that would have a longer range (ie. a couple of feet)? Or would there be any other solutions that would have the same range and is not too expensive?


Are there any transmitters that do not need to be connected to an Arduino?

arsenal4vr: @WillR

Are there any transmitters that do not need to be connected to an Arduino?

Look at this one...

None them need to be connected to an Arduino. You can generate the data signal in lots of ways. Maybe your communications knowledge is a little weak... do some digging.

Dig around here to start. I know TI (Texas Instruments has some TxRx pairs)

Lots of people have the "Key Fob" type pairs -- you can do what you want with them.

See here:

The Keyfobs idea might help you understand.

I did a search here.

The keywords are --> receiver transmitter transceiver

You should then see this as one of the items. RF Receiver, Transmitter, and Transceiver Finished Units (531 items)

Sort by price ascending and then look -- I would say starting on second page.

It should bring up pages of stuff that could give you some ideas.

They may not be what you want, but you should learn how to approach your search for the items.

Room Key is present Where? in the guest's pocket or in the door inside the room, that would be the easiest but as I remember those types of locks are single exterior access devices only. I assume you are talking about Hotel Door Access keys? That was at any rate what I understood you to ask for?


Then there is this stuff...

Might be worth a look.