Nice one Rowan! Whats that thing attached to the seatpost?
Update:
My earlier replies in this thread must have been pretty close before I bought my first “good” bell. Maybe this thread inspired me. For my main road riding environment (American River Bike Path), a ratchet bell is the best. The ‘ding’ bells aren’t loud enough to register most of the time. Like in that Japanese video, the ratchet bell sends the signal to move over, so most people just do and don’t need to look back.
I love how the Japanese guy gets creative at the end, triggering people to move over even on the escalator and in the narrow store aisle! For those not familiar with Japan, they do have huge amounts of bicycles used for commuting, so they’re well acquainted with sharing space with them. Also, in Japan you drive on the left; that’s why almost everybody moved over to the left.
I used to have a really loud bulb horn on my Excessory Cycle; it was great for parades as it really cut through all the noise you usually have there. It would be really fun to use on the bike path, but too disruptive. Usually I just want people to make a hole, not look back and then react to a unicycle closing on them. That horn is not seen in the photo in my earlier post; it was long gone by then. What’s on there is the “little” horn, which only carries a very short distance, especially in the noise of a parade.
Nice setup, Rowan. But your bulb horn will carry much further if it’s pointed forward. Right now, it’s having its greatest effect on your progeny, not anybody else. 
Of course, if you turn it around, it will be much more awkward to reach, so I understand the positioning.
It is a Fibre flare red light. Like a big red glowstick that runs on a battery.
I started with the horn mounted forwards, for maximum forwards horn blasting ability, but on my first UPD a few weeks after mounting it (I rode over a speed hump at night without looking and forgot it was there) the horn broke loose from it’s moorings because it protruded past the front of the handle. Only cable ties were damaged in the fall but it inspired me to try it the other way. I still get plenty of sound and half the time people I honk at are behind me. It is so much easier to reach with it oriented backwards, like you say. It was not hard to reach before but it is even easier now.
I use an Electra bell which makes the more traditional briiing briiing sound.
I was riding on a bike path a while back, just wide enough for two people to walk side by side. In front of me were four people in a two by two formation. I rang the bell in the hope they would move over to let me pass, the two people on the left moved to the right and the two people on the right moved to the left 
The cluelessness of pedestrians knows no bounds.
I have a ratchet bell, purchased for a few quid from ebay. I find it essential to have when riding on the pavement or in parks etc as the ring-ring is very assertive and people often move out of the way without looking behind. The internal mechanisms sometimes rattle but it’s not a big deal.
I’ve positioned it at the front of the KH bar for easy reach and it doesn’t interfere with the handles or my hands.
More like a “quote of the day” but…
As I passed 2 pedestrians on the bike…I mean unicycle path a couple weeks ago, I dinged my bell, and as I passed a man said, “Nice touch”.
I am buying
for my 36’er. Generally shouting “On your left!” works around here but sometimes traffic is too loud, or people have their music up too loud and they don’t hear me. Bike bells I’ve seen around haven’t been nearly as loud as I’d like. So I figured I’d pick one of these off amazon and give it a shot.
that is an obscenely loud horn…
I ride on obscenely loud roads sometimes. Almost any direction I go from my house to get somewhere I have to ride near the highway or on a very busy/loud road.
Oh man, that looks like what I need Ducttape. I’d love to check it out when you get it going.
Brycer