In this instructable I'll show you how to build a wireless intercom for short-range two-way communication. You can use this to chat with another person on a bike ride, or on motorcycle rides with helmet-mounted bluetooth headsets (that's my next instructable.), all while sharing your music or podcast (from iPod, cd player, etc.) This one is almost too simple for me to take credit for, since I'm really just repurposing a bunch of things and just making a very simple adapter to make them work together. That's good news for you though, because that means it's very simple, and though it's unlikely that you'll have everything just laying around, at least some of you will have a couple of bluetooth headsets handy.
Step 1: Buy Some Stuff.
So you'll need a few things for this, first you'll need to search eBay for "Motorcycle Intercom". Amongst all of the really good (and expensive) intercom systems, you'll find the very inexpensive (usually around $25.00 shipped) wired intercom systems that use standard 2.5mm cellphone headsets. These can probably be used for other things, so don't throw them away, but put them aside. We wont be needing them.
Next we need the Jabra A210s (or any bluetooth to 2.5mm wired adapter). I found these cheap ($20 each) at cell Xpo, link, so I used them over the Cardos, which were about $50.00 each. These will plug into the motorcycle intercom module where the wired headsets would have plugged in. See what we're doing here?
In my intro page, I mentioned that very basic soldering is required, but if you get one of the el cheapo intercom systems and find that the connectors are 2.5mm, you actually wont need to do any soldering at all. Mine is actually different from the ones most commonly found on eBay, and had 3.5mm jacks, so I needed to adapt the 2.5mm jacks to the 3.5mm ones on the intercom.
Lastly, you'll need to buy a couple of standard Bluetooth headsets. If you're in the states you're in luck. Recent legislation in my home state of California has required that anyone using the phone while driving do so with a handsfree kit, which means a bunch of online retailers are making great deals on Bluetooth headsets. I got a two pack on buy.com for $20.00.
Step 2: Pair the Headsets
Now you'll pair the headsets to the Jabra A210s. Try and remember which adapter is paired to which headset. Plug the adapters into the intercom and power the intercom up. Remember that the distance limitation is not between the two headsets, but rather between each headset and the adapter to which it is paired. This should give you a maximum range of about 60 feet, which is more than enough for a bicycle-to-bicycle or passenger to rider.
I also velcroed the entire shebang together for portability (with all the coily wires it looks mighty suspicious - don't try getting this one past airport security.) and put it into a zip-up camera case, then in my bicycle saddle bag or the compartment on my motorcycle to keep it protected.
That's it, please let me know how this instructable works for you, as always vote me up if you liked it, and enjoy!
Step 3: What to Expect / Dealing With Road Noise
Obviously, the headsets we'll be using aren't meant to deal with the kind of noise you'd find on a bicycle or motorcycle. We'll need to modify the headsets to shield the microphone from these noises, and as with all acoustics, that's not exactly easy. I'll be updating this instructable as I go along, but for a minimum amount of reduction of wind noise, I spread some hot glue around the area of the microphone. This helps cut down on some wind noise (I'd say by 30% or so), since now the wind isn't whistling through the microphone hole. It's a start, and I'll be doing my own experimentation but if anyone has any ideas they will be greatly appreciated.
This intercom setup will vary greatly depending on the hardware you choose, for example my initial results with a plantronics and LG headset were less than desirable, where the cheapo $20/2pack headsets are quite good. If you look closely in the picture, I've labeled each headset and each adapter with an "R" (rider) and a "P" (passenger). This is helpful for troubleshooting purposes.