Build your own cycleradio™ to listen to music on your bycicle without batteries

2008 notice: this article is way outdated now that lithium MP3 players are sold for a few bucks, still you can feel like a nerd and build this contraption out of sheer fun.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.

Let’s proceed.

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.

Hey, are you sure it is 6V?
This is the prize for your quest, brave knight. Pssssst noone’s around, get a screwdriver!


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:

4 diodes:

Anyone of'em is ok. If you know how to use them :-P
A diode is represented as –>|– where the point of the arrow is the positive pole. The side of the diode with the black or coloured ring is the positive pole.


1 capacitor:

Do not pull those wires!
These are two examples of what you need. Better get a capacitor of some Volts higher of the dynamo’s, lilke 10-12-16V, and at least of 2000uF, or your walkman playback, during fast rides, will simply suck.


solderer (needed only to make a "clean" work; I didn’t use one)


And this is how you need to assemble them:

Admire the artistic talent...
Clear eh? Now, don’t cry and use your fantasy, it’s clear indeed. I put in here ALL of the components, so you’ll use this image as reference. Make sure the positive pole of the diode-square and the positive pole of the capacitor match. The same for the negative poles.


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:

Don't ever try this at home kids!
Place the scotch-packeted rectifier circuit right in the place marked with the bright-yellow dot. Place instead the scotch-packeted battery-pack in the place marked with the bright-green dot.


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?

One thought on “Build your own cycleradio™ to listen to music on your bycicle without batteries”

  1. [commenti dal vecchio sito]
    [comments from old website]

    2009-12-29 17:23:49
    ciao Ephest grazie della risposta, molto gentile. Proverò con dei led!
    2009-12-28 00:24:41
    In questo caso ci sono alcune soluzioni: trova una dinamo più potente, o mettine altre in parallelo alla prima (e non in serie, ti serve più corrente alla stessa tensione), e/o sostituisci la lampadina ad incandescenza con una a led (potresti ricavarla da una di quelle torce ricaricabili manualmente che vendono nei negozi cinesi) che a parità di luce consuma MOLTO meno. Buon divertimento!! 😉
    2009-12-28 00:20:22
    …forse hai fatto bene tutti i collegamenti (la righetta dei diodi corrisponde al loro lato positivo… almeno ricordo così, nel caso prova con un tester), ma il problema è la lampadina secondo me! Anche se diodi, condensatore e batterie funzionano bene, probabilmente la lampadina assorbe tutta la corrente della dinamo e non ne lascia neppure un po’ per far ricaricare le batterie.
    2009-12-28 00:17:08
    Secondo me il problema principale di tutto questo accrocco è proprio la lampadina! Io ci alimentavo un walkman, di cui non saprei proprio dirti l’assorbimento, ma ti garantisco che ad un minuto di autonomia ci arrivava da fermo ai semafori. Le lampadine ad incandescenza invece sono aggeggi che in proporzione a quello che illuminano consumano una eternità di corrente…
    2009-12-28 00:14:48
    Il primo è che il condensatore in questo caso non è così tanto necessario, la lampadina si accende anche se la tensione è alternata… mentre alle batterie basta che sia sempre dello stesso segno (sempre positiva o negativa), ed i diodi servono a quello. Il condensatore serve solo a non far dondolare troppo il valore della tensione ma non dovrebbe interferire con la carica delle batterie.
    2009-12-28 00:11:41
    Ciao Francesco….e grazie per l’interesse! Questo articolo l’avrò scritto una decina di anni fa… comunque da allora le leggi dell’elettronica non sono cambiate. Tu devi alimentare una lampadina, che normalmente è collegata direttamente alla dinamo; se però deve stare accesa da fermo giustamente ti serve la batteria che faccia da tampone per la carica… ci sono alcuni fattori da considerare.
    2009-12-27 23:40:41
    …vicina al condensatore che è da 16 v, 3300 microfarad simile a quello a destra della foto.
    La dinamo è da 6 v 3w.ho delle batterie ricaricabili da 1,2 v .
    Servono delle caratteristiche precise dei componenti o questi vanno bene?da quel che ho capito le batterie dovrebbero ricaricarsi pedalando giusto?Se non ho fatto confusione ti chiedo un minuto per dirmi cosa ne pensi.grazie e complimenti
    2009-12-27 23:28:28
    ciao,premesso che sono un neofita del settore volevo dire che ho messo insieme i pezzi come nel tuo schema o almeno così credevo .
    Io vorrei poter usare la dinamo per alimentare il fanalino della bici in modo da averlo acceso anche quando sono fermo.Mi chiedevo:
    -come devono essere i diodi? ne ho usati 4 simili al 5 tipo da sinistra nella foto sopra,collegandoli con la lineetta bianca vicina
    2009-12-07 14:25:25
    Ciao bruno, e grazie del tuo intervento 😉 Questa guida è stata scritta probabilmente 8-9 anni fa, quando avevo tonnellate di tempo libero, adesso mantengo il sito solo per fare onore ai bei vecchi tempi. Ma ricambio con molto piacere gli auguri, e magari le feste saranno occasione per cimentarti nell’impresa!
    2009-12-07 00:47:05
    Molto simpatico nella descrizione.
    Appena avrò un po’ di tempo proverò a relizzarlo.
    Ci sono altri “progetti”?
    Grazie ed auguri.

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