Portable Wireless Motion Sensor Triggered Alarm With a Wireless Doorbell and an Airwick Motion Sensor




About: Electronics geek, Openwrt, Linux, hardware hacker, maker, SF fan.

I had the idea to combine these two items for some time now, so when a local store got the wireless doorbell for about 11,50USD I just had to buy it....

Parts and tools needed:
Soldering station
Something to cut the pcb
1x tip31 transistor
1x Airwick motion sensor
1x Wireless doorbell

Step 1: Digitized Sensor Input


Tnx Doug Paradis, this step gave me some trouble.
I only changed a part of his method, I just used some solder and no drilling.

Step 2: The Idea

EDIT: I recommend  you add a power switch between the center tip31pin  and the negative  circuit contact, the circuit loves to eat batteries!

The tip31 can be replaced with 2n3055 :)

Step 3: The Finished Project

I was in a hurry, and had no idea for the transmitter housing so i put it all in the airwick housing. I hope to hear your ideas and adjustments.




    • Trash to Treasure

      Trash to Treasure
    • Build a Tool Contest

      Build a Tool Contest
    • Weaving Challenge

      Weaving Challenge

    13 Discussions


    6 years ago on Introduction

    Your idea has catch our attention which led us in trying our own version of your project. We came up with the idea of using your project in replacing the traditional way of using doorbell. Is it possible that we can place the digitized motion sensor outside the house while the triggered alarm would still function even though it shall be placed inside the house? We are just concerned about the maximum range in which the two different yet connected device will work. Hopefully you did get my point. Thanks for any comments/suggestions. Godbless!

    1 reply

    Reply 6 years ago on Introduction

    Yes, there is a slight voltage drop on the transistor that can limit the distance, but if your doorbell alone can reach the required distance,and the finished thing not than you can add a 1,5 battery in series with the doorbell button battery, or add a 8 USD el.magnetic relay. Then connect the coil of the relay to the tip31, and the bell button to the relay's open contacts. If you do that your doorbell will function in the exactly the same way originaly intended, but you need an extra battery for the relay.


    6 years ago on Step 2

    So this will be my first real attempt at this. Is there any way that you could give the name and model of the wireless doorbell that you used? Perhaps you can provide better pictures now more clearly showing where things are connected on the transmitter?

    2 replies

    Reply 6 years ago on Introduction

    The door bell model is not an issue, this circuit should work with any model.
    The positive side of the battery connects where it was always supposed to connect. The batteries negative end connects to the tip 31 ground, and the tip31 center pin connects to where originally the batteries negative was connected to the housing. And you use the battery that was intended for the bell.
    Il check out the model. Hope I helped.


    7 years ago on Introduction

    This was littelary what I was thinking of today :P Would it be possible to connect to pc and make it like a loud alarm coming from te pc? A bit like this one actually ()

    7 replies

    Hypothetically I believe you could do that, but it'd be difficult. You'd need to some how convert the alarm portion into a digital input to send over a USB cable to your computer. It'd be a lot of work. Unless I'm way off base.


    Reply 7 years ago on Introduction

    Actually you can rig any input device to send the signal to the computer,and than its all about the software. Im just looking for the cheapest/easiest way to do it,and then i will post. The mic input on the sound card could be used with a program like webcamXP to do what ever you want when it hears something from that input.You could rig anything, a keyboard, an usb device , usb,serial port...
    I will try to make something cheap and easy :)


    Reply 7 years ago on Introduction

    I actually came up with a pretty simple idea. Wire it through a spare keyboard, and you can have multiple sensors set up at once. Then use a program, say MIT Scratch (a basic game creator by MIT. and its free), and just hot key alerts (just word bubbles) to the keys on the spare keyboard that you wired the alarm to. Only problem is that you would have keep the scratch game open for it to work.


    Reply 7 years ago on Introduction

    Well im happy with the i spy mic setup for now, and it suports multiple mic`s/cameras.It can be set so that it plays any program/playlist/sound/comand so its very nice.It could be used for non wireles motion operated comands :)
    Well anything is posible, the real question is: What do you need :).
    And orks from tray. try it :


    Reply 7 years ago on Introduction

    Here`s the upgrade, Il post the instructions within a few days .


    Hope you like it! Its conected over the mic input. The voltage must not exceed 0.7V! The software used on the computer is iSPy .chears:P