Introduction: Reminder Box - Motion Activated Recorded Message Player

About: I am an American teaching English at Shangluo University, Shaanxi. I like making machines that do interesting but fairly useless things - I call them Quixotic Machines.
I wanted a device that I could use to help me remember stuff or force me to practice remembering stuff. So I built this Reminder Box that is simply a voice recording module connected to a PIR (Passive Infrared sensor) so that each time I pass by the box, a recorded message will play. Great fun and easy to build.

Parts list:
- ISD1820 voice recording module - lets you record a message and play it - about 6 dollars plus shipping
- Passive Infrared Sensor (PIR) module - couple dollars plus shipping
- battery

A PIR will activate and play the message then it will not do anything if you continually move in front of it. When there is no movement for a few seconds, the PIR resets itself and will again activate if it detects movement. Each PIR module has different reset times and these can usually be changed if you change a component on the board - too much work for me.

Note: the ISD1820 amplifier is not really loud. If you need more volume you could connect the SPKR terminals to an external amplifier or to an LM386 chip (too much work for me). You can increase the speaker volume some by gluing a section of toilet paper tube to the back of the speaker - amazing how just holding the speaker in your cupped hand ups the volume.

I am using this box to record Morse Code so that I can practice decoding messages. 
I also should record "Jim, you're too fat, quit eating!" and put the box on the fridge.
I also want to use it to practice my Bible memory verses.
Lots of stuff one could use it for.

Step 1: Check Modules to See If They Work

The wiring diagram shows how to connect the PIR to the ISD1820 with a battery.

To test the PIR separately just connect the PIR to a battery just connect the positive and negative terminals. Then connect a 400k (100 to 1K is ok) resistor from the PIR out to an LED (positive lead)  and then the LED negative lead to ground. Motion in front of the PIR will turn the led on.

Using a PIR module that has the same voltage range as the ISD1820 will vastly simplify this project as you will not have to step down the voltage for one of the modules. Both of my modules use 3.5 to 5 volt range.

Now some folks say you need a pull up/down resistor between the PIR out and ground but mine works fine without it. My module may have that circuitry built internally. Don't know, don't care.

The "P-E" on the ISD1820 means the PLAYE terminal. When this terminal receives high voltage from the PIR out, it will trigger the recorded message to play.

Step 2: Build Container

I used a tin box that tea comes in. I like to use these containers because they look nice just sitting around.

First I drilled holes in the lid for the speaker and to mount the ISD1820 board on the inside.

I cut a little piece of EPP foam insulation to mount between the lid and the board to prevent any shorts.

The speaker magnet actually holds itself to the lid so I didn't glue it down.

Finally I cut a hole in the side of the tin box to mount the PIR. You should probably superglue, hotglue or epoxy the pir plastic lens to the box.

Step 3: Wire Sensor Modules Together and Mount in Box

This picture shows the modules mounted and connected together with a battery box mounted inside the tin box. My wire leads are kind of long but to record a message you have to take the top off the box and press the red button.
Thats it!

Things that could be done to make it a little easier to use:
- should wire in an on/off switch for the power
- could mount the microphone and record button on the outside of the box so as to be able to record message without opening the box.
- could wire a LED from the PIR out to see when the PIR is active
- cound add external jack for external power

You could also connect the PIR to an Arduino board and program it's function but I just wanted a message to play when the PIR was activated so that did not necessitate any additonal modules or programming.