Build a 555 based adjustable timer. The 555 timer IC is a great little device.
It can be used in many different applications.
In this Instructable, we use the 555 timer to create a countdown timer. The timer starts with a shake and ends when the LED stops glowing. There's no fancy accelerometer, no Arduino, no coding, just a 555 chip, some miscellanous discrete components and a tilt ball switch. The timer can be adjusted from one to about ten minutes. This particular timer was intended to be used between sets during weight lifting sessions. That is why it is only a one minute timer.
The final design is really version 1.5. The first version was designed to flip to start and flip to reset.
See the photos. The tilt ball switch proved to be too sensitive for a flip design. The circuit was redesigned to trigger on a shake. Hence the birth of the Shake Timer!
A big thanks to these sites for the circuit design.
Adjustable 10 Minute Timer Project
Bowdens Hobby Circuits
Hot Glue Gun
Proto Board - Radio Shack P/N: 276-148
555 IC - Radio Shack P/N: 276-1718
100K Resistor (times two) - Radio Shack P/N: 271-1347
470 LED Resistor - Radio Shack P/N: 271-1317
1Meg Trimmer Pot - similar to DigiKey P/N: 3309P-105-ND
8 Pin DIP Socket - Radio Shack P/N: 276-1995
220uF Capacitor - Radio Shack P/N: 272-1029
0.1uF Capacitor - Radio Shack P/N: 272-1053
Green LED - Radio Shack P/N: 276-022
1N4001 Diode - Radio Shack P/N: 276-1101
9V Battery Clip - Radio Shack P/N: 270-324
9V Battery Holder - Radio Shack P/N: 270-326
Tilt Ball Switch - adafruit
Micro Power Switch - Electronics Goldmine P/N: G16674
2.5 inch diameter mailing tube - recycle bin
Adhesive backed printer paper
Clear adhesive backed shelf paper or clear laminate
Step 1: Build the Circuit
The photos show a modified version 1. A less ugly verion can be put to together when starting from scratch.
When done soldering everything, test the circuit. Temporarily attach the battery, power switch and LED. Shake it. The LED should light up for a period of time and then turn off. Adjust the length of time the LED stays on by adjusting the trimmer pot.