Sometimes its really important to have a stereo system for your bike. SCUL has a ‘standard’ method by which they use a 12V SLA hooked up to a car stereo which is then wired to some car speakers. It’s cheap and easy but I’m never one to leave well enough alone. Thus my ultra-light/ultra-efficient pimped-out bike stereo system:
2 x 7.4V 4Ah Lithium Ion Camcorder batteries = 15V at 4A = 60W of power! ($20 each)
Class D amp. I use the TPA3001D1 you can get kits for this, I made my own PCBs cause I wanted to make at least 4 amps. Either is A-OK. up to 20W output! Is TSSOP so a pain to solder.
Cheap MP3 player (this one was ~$10, uses MMC cards and a AAA battery) You dont want to get your iPod all dusty. Requires an MMC card, a 256M is like $25 or something.
Speaker(s)! I recommend old car speakers. Making an enclosure for them will make them sound better but they’re sort of engineered for poor enclosure design. Cheap/thin cookpots work great and come with an attachment point even!
Because I’m using lithium ion batteries (twice the power per lb) and a class D amp (twice the efficiency, and also no heatsink to make it superheavy), the whole system (minus speakers) is 1lb. A speaker in a cheap pot as above is about 5lbs more.
Took it out of storage and tested it on a $2 speaker which promptly died from overdriving it 🙁
[flickr 217458872 ]
OK well, now to hook them up to the big speaker. Lookin’ good!
[flickr 217459058 ]
Here is a closeup of the board
[flickr 217458621 ]
And the files for the PCBs, make sure to read the datasheet to see what is up with the parts, this is otherwise undocumented
I used MOLEX Micro-fit 3.0 connectors for the wiring harness. These are awesome!
Solder directly to the camcorder plugs to avoid having to get the wierd micro-banana plugs but then…
Wires go through a lot of stress here so use zipties for strainrelief as shown.
You’ll need a 7.4V battery charger for LiIons. I made one using the BQ2057 chipset, or buy from your favorite online battery store. Or just give it 1/4C 8.4V with some power supply. I’ve seen people use LM317s…hey whatever works for you
Be careful, I overdrove the two cambridge soundworks speakers (they lasted 6 days tho!). Bring extra speakers or just use big speakers so you’re safe
Bass response sucks…thats just what you get for having a system like this.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.