Bike Speaker




Introduction: Bike Speaker

About: just have to figure out how all these things go together....

It's completely powered by a dynamo hub generator... completely off-grid bicycle powered 'fun box.' Puts out plenty of sound for a scrapy speaker... I already got an 8" 2-way speaker in the mail for the next generation sound system.... soo much fun to have sound blasting up at you instead of through your ear buds ... much safer too!

inspired by a derailleur sound system from specifications from Dan in Oakland

The bicycle rack in the video is from the chunk666 engineer, Tad who makes TCB racks.

One month ago a weekend of bike events called 'Freak bike fall'  was happening and there was a nicely sized LOUD sound system running on 24 volts and I was told it was only pulling 1/2 amp by this likable character that called herself agent flux...

...and I thought out loud, "Damn I can run that off my Dynamo-Hub... 

... I was definitely not 100% sold that it was all only pulling 1/2 amp and I wasn't carrying an amp meter on me soooo....

I decided to start small and this is the 1st generation $2 speaker and the dynamo power goes right to the amplifier and blows it away....

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Step 1: So First I Ordered Some Parts

Amplifier: Sure Electronics 2x15 watt TA2024  for $22

Crossover: Monkeylectric monoXover for $15

I already had a dynamo hub: Shimano DH 3N71 ... they are all pretty much the same, 6 volt / 3 watt

AC to DC 'bridge' qty(4) 1N5818 Diodes $0.29 each

Step 2: Found Some Speakers

I was looking for a 2-way speaker; that is, one with a small speaker (tweater) and one with a bigger speaker (woofer).... well the woofer didn't have a lot of woof in it... more on that later...

Goodwill has a place where they ship all the crap they can't sell (a lot of stuff).... Its the last place before it goes to the dump they tell me.... 
I went to 'the bins ' and bought a bunch of cheap speakers for $2/each to try..... 

Step 3: Dismantled the Old Speaker

Step 1: took apart the speaker

Step 2: took out all the wires including the old crossover

Step 4: Add Some Extras

So I did a bunch of extra stuff that ate into my time... went from a 4 hour project to a 6 hour project... here they are and feel free to skip this stuff... except for the battery... you might want that for hanging out in the park....

I wanted an easy way to either power the speakers AC or DC so I added two inputs for power..... Why DC? because I'd figure I might have a 12 volt battery I could just power it straight if I'm hanging out in the park for a few hours.... I could also charge the battery while biking around.... If you check the pictures out i made a separate input for DC but I should have just used the same slot.... right? DC should pass right through the diodes unaffected.... woops! ... but then again.... If you have the battery hooked up while riding.... it should charge the battery as well or at least when the music is OFF or not at full volume..

Next I added a 1/8" plug in for the IPOD...

I pulled a 12 volt battery  out of a APC Backup Power strip  from Goodwill. See Dan's Instructable for other places to find batteries...

..."12V "SLA" type batteries are very inexpensive, and also easy to find at recycle yards. For a new one try . A 7.0 Ah capacity should last you all day and costs $20. They also have a nice charger for $15. Amazon has these batteries too."

Step 5: AC - DC Bridge

I need to change the voltage from AC to DC... that is, from AC from the dynamo hub to DC to the amplifier..... It goes from the dynamo through the bridge and straight into the amp... NO circuit protection... living on the edge is fun.... I'll update this Instructable if it blows up....

I've done this before and it is really simple... you have to solder four diodes in the shape of a diamond and you are done....

AC to DC 'bridge' qty(4) 1N5818 Diodes $0.29 each

check out this other instructables....  Dnyamo - lights

The wikipedia article is a little exhaustive....

Step 6: Put All the Expensive Stuff in the Box....

I would refer to Dan's original bike sound system instructalbe here .

Also Dan's crossover instructable here .

Everything wires together pretty simple.... You go from a stereo IPOD to the crossover that makes one channel the tweater and one channel the woofer that then gets amplified and sends the MONO amplified signal to the respective speaker...

Ipod goes to the Crossover IN.

Crossover OUT goes to AMP IN (the amp comes with the 1/8" male to coxial cables).

Amp connects to speakers:
Right, Ch1, Red is Tweat,
Left, Ch2, White is Woofer.

AC Power from the dynoamo hub goes to the diode bridge. 
DC Power from the diode bridge goes right to the amp board... (thats right! no circuit protection... I'll update this if I blow the amp)...

You can adjust the crossover with the Monkeylectric onboard resistors...
R7 is controlling Right Channel (Tweat,Ch1,Red): Clockwise (maximum)
R8 is controlling Left Channel (Ch2,Woofer,White): CounterClockwise (maximum).

In summary I'd say that it puts out as much sound as that shitty speaker can handle.... My dyanmo hub can push more power than the speakers can handle... even only using the TA2015 amp  rated at 15 watts... I could easily invest in a slightly better speaker for superior performance.... 

Its soo much fun to have sound blasting up at you instead of through your ear buds ... much safer too!

The woofer is hard to control because the bass is so different from song to song...and the speaker is so scrapy... Dan's crossover has screw-adjustments for both the tweater and woofer so that makes it easy to adjust....

So what's next?  I'm going bigger.. just ordered the next bigger amp from china.... 20 watts and a 2-way speaker with an 8" woofer...
3/15/11 Purchased the following
Tripath TA2020 Mini Cute Class T Amp Amplifier Ipod MP
Ebay seller:indeed-hi-fi-lab

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    5 Discussions


    7 years ago on Step 6

    Thank you for this. I have been following Dan's instructions so I purchased all the items. Just waiting for the speaker to arrive.

    I had a few question that I needed clarification on and your project answered them, so thank you :-)


    Reply 7 years ago on Step 6

    I have a question, actually. What type of cable do I use to connect the battery and amp?


    8 years ago on Step 6

    so even though the dyno is 6v, it is enough to power the amp?


    8 years ago on Introduction

    Impressive! I'm going to have to get you to help me with one of my future builds. ;)