A device that gives you reminders when you need them most

To activate it, just walk by.

By Mike Rigsby | Published Jun 11, 2009 3:29 AM EDT

A man wearing a gray polo shirt using a wall-mounted electronic device to record himself saying "Dentist appointment, Tuesday at 3:00." — Set it and forget it. Peter Pachoumis

This story has been updated. It was originally published on June 11, 2009 and involves outdated technologies. For current advice, check our regularly updated story about how to set phone reminders for anything, or learn how to use motion sensors.

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.

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.

A four-panel comic about a device that allows you to leave yourself a reminder for anything. The first panel is a man in a gray polo shirt talking on the phone and giving a thumbs-up because he finally made a dentist appointment. The second panel is the man using a wall-mounted electronic device to record himself saying "Dentist appointment, Tuesday at 3:00," so he can set a reminder for Tuesday morning. The third panel is the man about to open a door and the device says "Dentist appointment, Tuesday at 3:00." The final panel is the man in a dentist chair shouting "root canal?!" as a dentist ominously washes their hands in the foreground. — Give voice to your to-do list. *Peter Pachoumis*

Parts

Part	Part #	Source	Price
PIR sensor module	276-033	RadioShack	$9.99
Recording module	276-1323	RadioShack	$10.79
NPN transistor	276-2016	RadioShack	$0.79
0.0 uF cap, 50 volts	272-1069	RadioShack	$1.49
SPST pushbutton, sw red	26623	Jameco.com	$0.66
SPST pushbutton, sw black	26649	Jameco.com	$0.70
Perforated board	276-1395	RadioShack	$2.79
Wire wrap socket	37411	Jameco.com	$1.19
LM555 integrated circuit	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
1K resistor	30BJ250-1.0K	Mouser.com	$0.22
470K resistor	30bj250-470K	Mouser.com	$0.22
4.7M resistor	66-RCO7GF475J	Mouser.com	$0.25

Instructions

A homemade voice recorder and reminder. — Match the letters to their counterparts in the steps below. *Luis Bruno*

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.

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.

Projects

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