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 🙁
OK well, now to hook them up to the big speaker. Lookin’ good!
Here is a closeup of the board
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.
Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.
Join us every Wednesday night at 8pm ET for Ask an Engineer!
Learn resistor values with Mho’s Resistance or get the best electronics calculator for engineers “Circuit Playground” – Adafruit’s Apps!
Maker Business — Nottingham ‘internet of things’ firm facing closure @365_Agile @WirelessThings
Wearables — From floor to sword
Electronics — Can’t afford a current probe?
Biohacking — OpenHumans – Donate Your Data to Science
Sorry, the comment form is closed at this time.