I came close to dancing on my first speaker build.
Screwdriver on front of speaker bolt and spanner on rear.
Slipped and screwdriver went right through the cone !
I pulled the paper back and glued it and it worked fine for many years.
Some fair ground rides are based on the same effect.
They have one in Blackpool UK. The ride goes up vertically and then just drops and magnetism slows it down.
No, definitely not.
The kind of ride he is talking of is a vertical free-fall thingie. No unreliable moving mechanical parts for the brake system needed (apart from the very last centimetres). It is "always on" so to say. On the following picture you can see the contrapment rising up to approximately the same height as the palm trees:
https://upload.wikimedia.org/wikipedia/commons/0/07/Mp_high_fall.jpg
The magnets are installed on the shuttle (or whatever it would be called). Attached to the tower you can see white fins (a full dozen in this case here), starting at different heights in order to obtain a smoother breaking effect. They go into the air gaps of the large permanent magnets mounted on the shuttle. The faster the fins move relative to the air-gaps the higher the braking force.
There are tons of uses of the effect from electric energy meters, old-fashioned mechanical speedometers, magnetic brakes in old-fashioned multimeters (in order to avoid the eternal swinging back and forth of the needle every time the input voltage/current changes).
Eddy-current brakes (retarders) in trucks are another use of it. I once visited a high-wire park where there was a thingie used for automatic abseiling I guess that one worked with a eddy-current brake as well.
There are contrapments in vending machines that check the alloy of coins by measuring the free fall speed of the coins in a mgnetic field by the use of light barriers.
etc etc
Regards
Charles
The kind of ride he is talking of is a vertical free-fall thingie. No unreliable moving mechanical parts for the brake system needed (apart from the very last centimetres). It is "always on" so to say. On the following picture you can see the contrapment rising up to approximately the same height as the palm trees:
https://upload.wikimedia.org/wikipedia/commons/0/07/Mp_high_fall.jpg
The magnets are installed on the shuttle (or whatever it would be called). Attached to the tower you can see white fins (a full dozen in this case here), starting at different heights in order to obtain a smoother breaking effect. They go into the air gaps of the large permanent magnets mounted on the shuttle. The faster the fins move relative to the air-gaps the higher the braking force.
There are tons of uses of the effect from electric energy meters, old-fashioned mechanical speedometers, magnetic brakes in old-fashioned multimeters (in order to avoid the eternal swinging back and forth of the needle every time the input voltage/current changes).
Eddy-current brakes (retarders) in trucks are another use of it. I once visited a high-wire park where there was a thingie used for automatic abseiling I guess that one worked with a eddy-current brake as well.
There are contrapments in vending machines that check the alloy of coins by measuring the free fall speed of the coins in a mgnetic field by the use of light barriers.
etc etc
Regards
Charles
I do that all the time 
When I deliver my cabinets to guitar players I often finish them before customer´s eyes, because they get to decide Tolex colour, choose which speaker model they prefer, etc.
And half for practical reasons, half because I know it always trigers an "oooohhh!!" reaction, I casually throw a fistful of screws on nearest speaker magnet ... where even more complex spatial structures are created.
When I deliver my cabinets to guitar players I often finish them before customer´s eyes, because they get to decide Tolex colour, choose which speaker model they prefer, etc.
And half for practical reasons, half because I know it always trigers an "oooohhh!!" reaction, I casually throw a fistful of screws on nearest speaker magnet ... where even more complex spatial structures are created.
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