If zombies are around you and found shelter and want to have some sleep, you may find wireless mobile anti-zombie alarm very helpful. This alarm can be made out of a wireless door bell and motion sensor, which you may find almost everywhere.

You may leave the transmitter anywhere and it will send a radio signal to the receiver in you pocket, once a zombie is detected by the infrared sensor.

Let's see how simple it is to make it.

BE CAREFUL - THIS PROJECT PARTIALLY INVOLVES 220V

Step 1: Upgrading the Receiver

The first thing is to upgrade your standard door bell receiver so that it could perform in two regimes:

(1) LED-light (in order not to make noise when the zombies are around you);

(2) Sound alarm with adjustable sound volume (to make you awake if you are sleeping).

To do this you will need:

(1) Standard wireless door bell receiver;

(2) Switch with three positions (the three positions will be: OFF, FLASHLIGHT and SOUND);

(3) LED. I use the one that already has a built-in 220Omh resistor (so you will not find resistor on the photos);

(4) Potentiometer. I use 0-1kOmh, so there is still some sound playing even in the 1kOmh position (you are free to chose the one potentiometer which meets you sound requirements best).

Do the following:

(A) Disconnect one wire from the sound speaker (the one which goes from the receiver chip);

(B) Connect the wire from the chip to the general terminal of the three position switch;

(C) Connect one output terminals of the three position switch to the sound speaker; Disconnect the other wire which goes from the sound speaker o the ground and introduce the potentiometer in between;

(D) Connect the other terminal of the three position switch to the LED (do not forget to check the polarity of the LED); Connect the other leg of the LED to the ground.

Now you have a perfect receiver which may either make sound with adjustable volume lever or blink the LED

Step 2: Preparing the Transmitter Electronics

The purpose of this step is to connect the transmitter to the motion sensor using solid state relay. To do this you will need:

(1) Wireless door bell transmitter (you can get it out of the standard wireless door bell "button";
soder in the
(2) Solid state relay (I use the one made in Russia - КР293КП1Б, but you may use anything with low output resistance and appropriate voltage characteristics). Alternative, you ma use a classical electromagnetic relay, but it is making "click" noise, which may attract zombies and it is rather big, while the case of our transmitter may be not so big to have space for everything;
;
(3) Infrared PIR motion sensor, which you may find in any Arduino store. I use HC-SR501;

(4) Short wires to connect everything.

Do the following:

(A) Connect the input pins of your solid state relay to the Output and Ground terminals of the infrared sensor (check the solid state relay datasheet to determine the exact pins);

(B) Connect and solder in the two wires to the terminal of the button on the transmitter's chip. If you connect them now, the chip will send a signal and receiver will make sound/blink;

Step 3: Making Case for the Transmitter

The goal of this step is to make a case for the trasmitter and put everything into it. After long hours of thinking about what may e a perfect case for the transmitter, I found that this is a good idea to have a standard rechargeable (220V rechargeable to be exact) flashlight as the case. The advantages of this approach are:

(1) It is very convenient - all electronics may be put into the "head" of the flashlight (of course, you need to remove the LEDs);

(2) It has an accumulator and built-it AC - DC converter which charges it;

(3) it looks like an industrial made device.

To do this you will need:

(1) Flashlight. Make sure that it has an accumulator and built-in AC-DC converter, so that you may recharge it exactly from 220V outlet. BE CAREFUL, SINCE 220V IS HIGH VOLTAGE AND MAY HURT YOU OR CAUSE DEATH. If you are not so surer, please chose on ordinary flashlight with batteries or some other case. Anyway, please ensure that the "head" of the flashlight is big enough to install all the electronics;

(2) Two-position switch (I removed the standard flashlight switch just because I wanted to have the one you see on the photo. If you are fine with the standard one, you do not need it).

Do the following:

(A) Remove the leds from the "head" of the flashlight; DO NO TOUCH/REMOVE ANYTHING THAT CONCERNS BUILT-IN AC-DC converter, SINCE IT MAY HURT YOU WHEN CHARGING, IF YOU DO SOMETHING WRONG

(B) Connect the two wires (power and ground) in the "head" of the flashlight to the Ground and VCC terminals of the Infrared sensor; Remember that the transmitter itself will be powered from a separate 12V battery which is usually installed on the chip of the transmitter;

YOU ARE DONE!!! CONGRATULATIONS!!!