Nice idea but doesn't that mean your jingling all the time ? I'd find that most annoying.
I've tried a few different warning gadgets but found that plebeians (sorry that should read pedestrians) not associating the noise with a bike ignore it.
The last device I tried was a pp3 powered mega horn left over from my motorcycle greenlaneing days,
LOUD enough to pass an MOT !
Freewheeling down hill on a shared use path I see a group of women folks walking side by side with there backs to me, from about 40 yards I gave a quick blast, no reaction. As I've gotten closer (25 yds) a longer blast, from there movement they obviously hear somthing but just carry on regardless, eventually when I'm almost on top of them and with a continuous blast from the horn the penny drops, they over react, panic scattering all over the path. That was the first & last time I used that horn on a pushbike.
I'm back to a good old fashioned bicycle bell "ring,ring-ring,ring"
In general people know the sound of a bike bell and react accordingly, if you don't want to shock them, ring it well in advance and they'll usually stop to see where the
bike is. Simples.
If it ain't broke don't fix it
If want bells try wearing one of these, I'm sure you'll be noticed
http://www.ebay.co.uk/itm/Jester-Hat-With-Bells-Multi-Coloured-Circus-Adults-Fancy-Dress-Accessory-/301835748271?_trksid=p2141725.m3641.l6368