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Wanted: Activity Reminder Device

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Back when I was growing up, I subscribed to Popular Electronics and built gadgets. My two most memorable projects were: (1) In the mid-1960s I built a panic box in an aluminum box. The speaker was driven by a dual mode relaxation oscillator. I took it to school. After pressing the button, the button retracted into the case and you couldn't turn it off. (2) In the early 1970s I built a Blue Box. I mounted a speaker and many pushbuttons in a small aluminum box. It didn't work. I used cheap components and it couldn't provide stable tones. Building electronic gadgets is very different these days.

As we all have read, we should not be sitting for long lengths of time. So I took a digital kitchen timer. I set it for 15 minutes. When it goes off, I stop and restart it, and then walk around for one minute.

There are two problems with this: (1) When I first approach my desk I forget to start the timer. (2) I think I'm going to leave my desk soon, so I stop the timer without restarting. But then I don't leave for a long time.

A custom activity reminder device would get around these two problems. Below is the device I'd like to have:


With buzzing and/or flashing signals, reminds person to get up from their chair every 15 minutes.
With an always on waiting state, the person will be reminded to start the timer when sitting down.
The device will reside near where one sits for long periods. It is not expected to move around.


- AA battery
- no on/off switch!
- timer buzzer
- 1/16" dia. white LED bulb
- LCD display with four 1/2" digits and colon in middle
- push button
- switch for silent mode


Waiting Routine:

Display counts seconds down from 9 to 0.
Exits to timing routine when pushbutton is pressed.
When it reaches 0 the LED flashes once very briefly.
Cycle restarts.

Timing Routine:

When button is pressed it starts timing.
Display counts down, starting at 15:00 minutes.
If button is pressed while timing, restarts at 15:00.
When zero is reached it goes into beeping.

Beeping Routine:

For 15 seconds:
- rapidly flashes LED intermittently.
- optionally intermittently beeps buzzer.
Numeric display flashes 0s. Or could count down from 30.
Exits to timing routine when pushbutton is pressed.
At end sends to waiting routine.


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I would use an arduino microcomputer with an arduino display shield for the display.

The best microcomputers are about  22$ down to a few dollars for the ones from China.

The arduino display shields are around 10$ or so. The Utlransonic distance measuring transducer senors

are less than 10$; they detect if you are in your seat or not.






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