A Device That Gives You Reminders When You Need Them Most

To activate it, just walk by

You’re late for work. As you hustle out the front door, the furthest thing from your mind is the afternoon’s dentist appointment that you’d scheduled last week. You’d have probably forgotten all about it — if you hadn’t thought ahead by programming a home-built device to give you a voice reminder as you pass it on your way out.

Give Voice to Your To Do List

Just record your reminder on the device (“Dentist at 3 o’clock,” or “Pick up the kids at baseball practice”), set the timer for when you’ll need to hear it — up to a week in advance — and from the set time forward, it will play whenever you walk near the attached motion sensor. Sure beats having to remember everything yourself.

DIY Voice Reminder


** Part Part # Source Price|**
PIR Sensor Module 276-033 Radioshack.com $9.99
Recording Module 276-1323 Radioshack.com $10.79
NPN transistor 276-2016 Radioshack.com $0.79
.1 uF cap, 50 V 272-1069 Radioshack.com $1.49
SPST pushbutton sw red 26623 Jameco.com $0.66
SPST pushbutton sw blk 26649 Jameco.com $0.7
Perforated board 276-1395 Radioshack.com $2.79
Wire wrap socket 37411 Jameco.com $1.19
LM555 Integrated Cct. 27422 Jameco.com $0.29
1 farad capacitor 142957 Jameco.com $4.49
Knob 162481 Jameco.com $1.49
Pot 500K with switch 263848 Jameco.com $1.59
4 AAA battery holder 216339 Jameco.com $1.55
Acrylic butter dish 104461 Clearlyacrylic.com $7.95
1 K resistor 30BJ250-1.0K Mouser.com $0.22
470 K resistor 30bj250-470K Mouser.com $0.22
4.7 M resistor 66-RCO7GF475J Mouser.com $0.25

1. Drill holes in your chosen enclosure, following the drilling template. Glue the speaker [A], microphone [B] and motion sensor [C] to the enclosure. Mount the buttons [D] on the outside.

Sound Circuit

2. Build the timer circuit board, which lets you specify a time delay after which the message will be enabled. Calibrate the timer.
3. Connect the timer circuit board to the “play” wire from the record module, the “play” button, the power wires from the battery, and the sensor and record modules.
4. Move the switch on the battery holder [E] to the “on” position. Hold the red button to record a message, and press the black button to hear it. Turn the rotary dial [F] counterclockwise to the “off” position. Turn the dial clockwise to set the time delay, after which any movement in front of the sensor will trigger the message.

A schematic diagram can be downloaded here.