Get of Your Ass Warning Shouting Device

New years resolution: not sit on my ass for too long. So I made a small device that shouts that I should get up, when I sit down for too long.

Based on this Radioshack recording device, a tilt sensor and a 555 timer, I now can not sit for longer than 20 seconds! This can off course be adjusted to longer times by playing with the capacitor and resistors in the 555 timer part of this project,

For this project you will need to solder onto the Radioshack recording device. If you are uncomfortable doing that, look up an instructable on basic soldering before proceeding. Other than that, no special warning or skills needed, so let's get making!

made by Rolf Hut: www.rolfhut.nl/english

Follow me on twitter: @RolfHut

for this instructable you will need:

• Radioshack 9V Voice recording module
• 9V battery
• breadboard and breadboard connector wires
• 555 timer IC
• resistors (1MOhm, 100kOhm, 10kOhm and 1kOhm)
• capacitors (10 muF and 1nF)
• NPN transistor (I use the BC547. This is the transistor that is in the Arduino starter-kit, many people have some laying around).
• tilt sensor (also: Arduino starter kit)
• enclosure that fits all of the above.

To test the 555 circuit, I further used this, but this will not end up in the final project:

• pushbutton
• resistor of 220 Ohm
• LED

and these tools:

• soldering iron
• pliers (small)
• hot glue gun or other good adhesive material / device. (duct tape will also work)

The 1MOhm, 100kOhm resistor and 10 muF capacitor together determine the charging time of the circuit and thus the time you are allowed to sit before the alarm starts shouting. By playing around with these two elements, the charging time can be changed to minutes if you like, but that would have made for a very boring video.

Unwrap the recording module, connect the 9V battery and record a message that you are comfortable hearing when you sit for too long. I choose for (the dutch version of) "Hey, get off your fat ass!". Test if the message is to your liking by pressing the button on the recording module.

Once satisfied with the recording, unplug the 9V battery and carefully remove the "play" button. Use your nails, or pliers, to bend the metal clips holding it in place.

Cut the ends of three breadboard wires and strip them a tiny bit (about 1mm). I consistently try to use "correct" colours: black for ground, red for power, yellow for data (in this case, for replacing the "play" button). Using colours like this is recommended, but not necessary. If you don't use colours, you may want to double check your system before turning it on. (This may be good advice even if you do you "correct" colours).

Solder the wires to the recording device as shown in the photo. The recording device has a voltage regulator on board which transforms the 9V to 5V. We will use the 5V for the 555 circuit. The + (vcc, red) and - (gnd, black) wire will be fairly easy to solder onto the board: just add them to the solder-blob already there. The button (yellow) wire may be a bit harder. I found it best to cut the wire down to just a few hairs, than carefully push these through the pinhole and solder on the other side.

Test if your soldering work is ok by plugging in the battery again and then touching the end of the yellow wire to the black first and then the red wire. You should hear your recording. If not, double-check your connections.

Build the 555 circuit as indicated on schematic above. This is the "wait for pulses" example from this website (credit where credits due). This is intended to integrate a number of pulses, and only then provide a high output. It will work equally well for integrating a constant signal coming in.

I use an LED in stead of the voice recorder and a pushbutton in stead of the tilt sensor to test the circuit and finetune the values of the capacitor and resistors that determine the timing of the system. When the button is pressed (ie, you stand up)the circuit quickly charges through the 100kOhm resistor, making the output go low (LED turns of). When the button is released (you sit down), the capacitors slowly looses it charge through the 1MOhm resistor, turning the LED back on after 10 seconds. Lowering the 100kOhm resistor, or increasing the 10 muF capacitor, increases all times. Raising the 1MOhm makes the "allowed sit down" time longer. Note that the 1MOhn should be at least three times the 100KOhm, otherwise the 555 never triggers.

Off course, you should test this with a proper 5V power source, maybe even the one coming from the recording module, but as the video shows, testing with 9V also works, because all relations are approximately linear.

Cut the heads of two more breadboard wires and solder them onto the tilt sensor. Replace the push button with the tilt sensor and the LED with the voice module as indicated in the schematic and photo above. Note the NPN transistor, and the 10kOhm resistor used a pull-up. Also note the current limiting 220 Ohm from the LED-test has been replaced by a 1kOhm resistor.

With everything connected, test the system, as I do in the video.

Triple check how the tilt sensor works, ie be very sure what position is "sitting" and what is "standing". Then decide on a way you want to attach the enclosure to yourself. I used a ducttape loop that fits around my belt. Once this is decided, glue the tilt sensor in the enclosure, under the correct angle. Once glued in, connect the electronics and "play" by turning it the way it woud turn when on your body. You may need to re-adjust the tilt sensor, it took me three tries to get the angle just right.

Jam all the electronics in the enclosure, taking care that you do not disconnect any of your breadboard wires. Close the enclosure. If your enclosure seals completely, ie. does not have any air holes, you may want to drill some small holes in it for the sound to "escape" and be better audible.

Attach it to your body (using whatever method works best for your combination of clothing / enclosure and body, I used a ducttape loop through my belt.) and be prepared to never again sit down for longer than 20 seconds.

There you have it: a "Get off your ass" shouting device to help with your new years resolutions. Do not forget to turn it off / take it off when you have your first meeting!