I'm very much a newbie on Arduino, I just bought my first Arduino a few months ago. Unfortunately, I've had a pretty heavy workload for a while now, so I haven't been able to play around with it much. I'm therefore hoping someone is willing to help me with the idea I have.
My problem is that I have very frequent migraine attacks. The main trigger seems to be stress (yay heavy workload...) and not relaxing enough. I was therefore thinking about a device that could remind me every hour or so that I should take a few minutes rest. I could buy a simple cooking alarm clock and annoy my colleagues and myself with the ticking noise and the alarm sound. Or I could use my mobile phone and set the alarm clock manually every day and keep it close. However, I often wear dresses or skirts, so no place to put the cell phone in, and I'm quite a disaster with keeping the thing around me all the time.
Another option I found are vibrating watches. However, these are either (or both) expensive and plain ugly. Seen as I'm a crafter, I would much prefer making a simple bracelet myself, and have a simple vibrating device in it.
I've found that Lilypad can be used to sew into clothing, and that there is a Lilypad vibe board. (http://www.sparkfun.com/products/8468) However, I don't know if and which other parts I need. I would assume the vibe board needs power. The problem is that the entire device cannot become too large: it needs to fit into or onto the bracelet. Next to that, I haven't figured out yet how to incorporate the timing function. Does anyone have any good ideas?
The Lilypad is 5" in diameter. A promini is ~1.25" x 0.75", a good deal smaller.
The vibrator.
You will need a battery, yes. Coin cell batteries are small. Not sure if rechargable.
Something to hold the battery.
Or not - this one is about the same size as the promini
Time source, unless you are using the uC as the time source, it can drift. http://www.sparkfun.com/products/10160 This might double as your battery holder also.
Recommend having the arduino go into power down sleep mode, wake up once a minute & check the time.
Larger LiPo batteries are not that much bigger either. No battery holder needed. Unplug the connector to charge it up.
Battery - Promini - RTC - Vibrator
Maybe a hexagonal bracelet? Sew up 4 little pockets to slide the pieces into?
This is a larger 1000mAH LiPo, 1.25" x 2" for comparison
You can get rechargeable lithium ion coin cell batteries which coupled with a pro-mini and a vibration motor should be well suited to your project.
If you purchased 2 or 3 coin cells - you could have one on charge while the other is used. Make them easy to slide in and out and replace.
As other people are probably thinking though - you don't need a break precisely on each hour so why go overkill with an arduino when you could just use a battery, 555 timer chip (with a few components) and a vibration motor. That could be extremely small with the largest part being the battery.
The Arduino indeed seems to be quite big. As for the overkill: I'm not very familiar with electronics, so I don't know about what is possible and what not. But a construction in which the battery is the smallest part sounds great! Would that be a coin cell battery?
I'll definitely look into the 555 timer chip, thanks for the advice!
There are lots of example circuits for 555 timer chips - you should be able to find what you're looking for relatively easily - and if you can't then they are a bit of a staple chip so most people know how to use them or at least could direct you to what you need.
Looking back, I am not sure where 5" came from. This seems more accurate:
Physical Characteristics
The LilyPad Arduino is a circle, approximately 50mm (2") in diameter. The board itself is .8mm (1/32") thick (approximately 3mm (1/8") where electronics are attached).
Either way, still larger than a promini. I think the idea of an 1.5" wide bracelet encircling the wrist with several little pockets would be viable.
Occurred to me last night that if this was indeed a watch, then a display would be needed also.
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