2008 notice: this article is way outdated now that lithium MP3 players are sold for a few bucks, still you can feel like a nerd and build this contraption out of sheer fun.
I made the whole thing myself, during a summer vacation, some years ago, when I was really, really, REALLY bored, so I came up with this weird idea. The system’s gonna be disassembled from my mountain bike shortly (still works OK after years of dust on the bicycle), just because lately (another summer vacation), I’ve had the occasion to make some long and rough rides, which I’ll repeat through all the holidays, and the walkman, which was going anyway to be trashed if I didn’t recycle it this way, doesn’t appreciate the frequent 1.5G shocks (my a$$ neither, but it’s another story…); plus the dynamo doesn’t fit well with the rear tyre at HIGH speeds.
Anyway, if you use your bicycle for city rides, not so fast as well, the CycleRadio will be your faithful bike-audio system for very, very long.
I’ll pass throught the graphic explanation of the manual steps, to come directly to explain HOW the whole thing is done and works.
Why? Only because if you are really unable to figure how to technically assemble all this, I can do nothing but recommend you to a good physiotherapist. And, not less notably, also because I don’t have a webcam to paste here the pics of how I did it on my bike.
Find a dynamo. Used, new, stolen from your neighbor’s ’60 bike, or from your mom’s ’80, but broken, one (as in my case). You should be able to get a 6V one, since it’ll give more reliability to the system.
Now you have to find a suitable place to fix it to the frame of your proud mountain bike. I chose the rear bracket which is normally used to attach the rear lamp (there are some nice holes where you need only a bolt to stick the dynamo). In the best of cases, you’ll need your brute strenght (better if helped by a solid pair of vanadium pliers) to fold the arm of the dynamo to make it rotate perfectly against the tyre (be careful here, placing the rotating part too tight may spoil the rubber, as placing it too near to the carvings of the tread will hurt often on the dynamo itself, causing it to be displaced very soon); also, you may need some steel wire to stabilize the structure to the frame).
Next, you’ll need someting to convert the AC of the dynamo to the DC which uses a walkman. And you may need to buy some electric pieces, if you can’t manage to remove them from an old TV, radio, or whatever.
This is what you need:
solderer (needed only to make a "clean" work; I didn’t use one)
And this is how you need to assemble them:
A good place to stick this small rectifier, which is the sum of the 4 diodes plus the capacitor (and which you’ll have packed in some Scotch tape, or better insulating tape, to make it waterproof, after you made sure there are no short circuits – just use insulating tape also on the bare contacts) is right about here:
Now you have in place the dynamo and the rectifier circuit. Mmmmm what next… why! Just wire them! You don’t need to connect specific poles, just one pole of the dynamo with one pole of the rectifier (not the ones connected to the capacitor, but the free ones) and then the other pole of the dynamo with the free pole of the rectifier (Important Notice Only For True L4m3r5: a dynamo has two poles, not only the one you can see at the bottom of it. The second pole is — try to guess — the bracket used to fix it to the bike frame!).
Let’s come to the batteries. Not the battieries you usually put inside a walkman, but every kind of rechargeable battery, the bigger the better, which has a Voltage of 6~9V (so, even the one of dad’s old cellular phone, if you know how to use its poles, or, as the ones I used, the rechargeable batteries of a broken portable vacuum cleaner…). You’ll attach the battery-pack somewhere else on the frame (see the previous pic).
In this case the positive output pole of the rectifier (the one on the side of the capacitor) must match with the positive pole of the battery, same for the negative poles.
One step to the victory!
Now, just wire togheter the positive pole of the battery with the positive pole of the walkman, same for the negative. You’ll need to open the walkman so to pull out the wires which actually reach the electrodes, and connect these wires with the wires coming from the battery (didn’t I tell you? The walkman will be lost, since, after that, you won’t be able to put batteries in it; so, better use an old walkman… you know the huge crappy one your grandma bought you for birthday, not knowing you already had an untraslim-single battery one? )
I suggest you to place the walkman on the handle-bar, right in the middle, where every mountain-bike has a short straight metal tube going from the handle-bar itself to its axis. Just fix here a small transparent zip-bag (like the ones used to put makeup accessories – here the mom will be useful again…) with a small table of plywood on the bottom, so to create a solid surface. Done.
You don’t need me to tell you how to pull cables from one piece to another do you?