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I had read about a few people hooking their cell phones up to the intercom on their bike. I had been thinking about this, but really didn't want to physically wire my phone into the bike - because this meant before riding, I'd have to get my phone out, plug it in, and stuff the phone in a fairing pocket or something - which is something I just wouldn't do: I'd never bother actually hooking it up.
What would be idea really, would be a Bluetooth module in the bike, so when I rode with my phone in my pants pocket, and it rang, I could just talk over the intercom on it, without having to touch the phone, or deal with any wires.
I started looking around at standalone Bluetooth modules, and was appalled - $120, $150, $200....all for a basic Bluetooth module that had the same functionality as a typical Bluetooth earpiece.
So instead, I decided to go cheap and see what I could throw together. I went to Target and bought the cheapest Bluetooth earpiece that I could find. It turned out to be a Jabra BT2040, that they were selling for $20. I see the same unit for sale on the Internet for under $10. This unit is perfect - it doesn't have a rechargeable battery inside it, you have to put a AAAA (yes, four A's - it's smaller than a AAA) battery into it, and when it wears out, you replace the battery. Because I planned to wire it into my bike, I didn't care that it didn't have a rechargeable battery - the bike would power it.
The first step was to build a power supply that ran off the extremely variable voltage provided by the bike (anywhere from 9 to 15 volts), and reduces this to a consistent 1.5 volts (actually I went with 1.7 volts, because that was easier to do with the components I had on hand). Because the bus voltage in the bike is notoriously noisy (the rectifier does not smooth out the AC from the stator into smooth clean DC, it's full of ripples and noise), I used some capacitors to clean it up and provide a nice, smooth, clean 1.7 volts.
Next, I disassembled the earpiece I had purchased. This earpiece has no volume controls, and everything is controlled using a single button. I cut out the microphone and speaker, and ran wires from them through some resistors to attenuate the signals, through some decoupling capacitors, and out to the bike intercom. I needed to bring the switch control out to the outside of the bike's fairing, so I had to disassemble the tiny switch on the earpiece and solder tiny wires to it.
Not 100% required, but the earpiece also had a flashing blue LED that let you know when it was on, and in use. I thought it would be nice to have a similar LED on the fairing, to give some idea of the operational status of the module. However, the LED itself was a microscopic surface-mount LED, so I had to desolder it from the earpiece circuit board, and tack solder some wires in its place, that I could then connect to a new LED.
Because of these two items (the switch and the LED), I would not recommend this for the average do-it-yourselfer. I have a stereoscopic surface-mount rework microscope and specialized soldering equipment to work with surface-mount components (the tip of the soldering iron is about the size of a sewing needle).
After I had tacked wires onto the earpiece circuit board, I hot-glued it to the main circuit breadboard I had created that held the power supply, and soldered the wires from the earpiece board to larger, more secure pigtails that came off the main board.
I took the whole thing out to my motorcycle, wired it in as a test, turned it on, linked it to my cell phone, and tried it out. To my surprise, it worked perfectly, the very first time! When my cell phone rings, I hear a special ring tone over the bike intercom, and a second later, it picks up the call automatically. I can then hear the calling party over the bike intercom, and when I talk, they can hear me. To end the call, I press the button that I wired into the earpiece.
When the bike is first turned on, the Bluetooth module does not come on - so I can ride in peace if I want. However, if I need to be reachable, I can turn it on after the bike is on by holding the button down for three seconds. If I like, I can turn it off by doing the same thing again.
I'm thrilled! I'm going to get an enclosure for it tomorrow, then wire it permanently into the bike.
If anyone is interested in the circuit I designed, let me know and I'll draw it up and post it.
I had read about a few people hooking their cell phones up to the intercom on their bike. I had been thinking about this, but really didn't want to physically wire my phone into the bike - because this meant before riding, I'd have to get my phone out, plug it in, and stuff the phone in a fairing pocket or something - which is something I just wouldn't do: I'd never bother actually hooking it up.
What would be idea really, would be a Bluetooth module in the bike, so when I rode with my phone in my pants pocket, and it rang, I could just talk over the intercom on it, without having to touch the phone, or deal with any wires.
I started looking around at standalone Bluetooth modules, and was appalled - $120, $150, $200....all for a basic Bluetooth module that had the same functionality as a typical Bluetooth earpiece.
So instead, I decided to go cheap and see what I could throw together. I went to Target and bought the cheapest Bluetooth earpiece that I could find. It turned out to be a Jabra BT2040, that they were selling for $20. I see the same unit for sale on the Internet for under $10. This unit is perfect - it doesn't have a rechargeable battery inside it, you have to put a AAAA (yes, four A's - it's smaller than a AAA) battery into it, and when it wears out, you replace the battery. Because I planned to wire it into my bike, I didn't care that it didn't have a rechargeable battery - the bike would power it.
The first step was to build a power supply that ran off the extremely variable voltage provided by the bike (anywhere from 9 to 15 volts), and reduces this to a consistent 1.5 volts (actually I went with 1.7 volts, because that was easier to do with the components I had on hand). Because the bus voltage in the bike is notoriously noisy (the rectifier does not smooth out the AC from the stator into smooth clean DC, it's full of ripples and noise), I used some capacitors to clean it up and provide a nice, smooth, clean 1.7 volts.
Next, I disassembled the earpiece I had purchased. This earpiece has no volume controls, and everything is controlled using a single button. I cut out the microphone and speaker, and ran wires from them through some resistors to attenuate the signals, through some decoupling capacitors, and out to the bike intercom. I needed to bring the switch control out to the outside of the bike's fairing, so I had to disassemble the tiny switch on the earpiece and solder tiny wires to it.
Not 100% required, but the earpiece also had a flashing blue LED that let you know when it was on, and in use. I thought it would be nice to have a similar LED on the fairing, to give some idea of the operational status of the module. However, the LED itself was a microscopic surface-mount LED, so I had to desolder it from the earpiece circuit board, and tack solder some wires in its place, that I could then connect to a new LED.
Because of these two items (the switch and the LED), I would not recommend this for the average do-it-yourselfer. I have a stereoscopic surface-mount rework microscope and specialized soldering equipment to work with surface-mount components (the tip of the soldering iron is about the size of a sewing needle).
After I had tacked wires onto the earpiece circuit board, I hot-glued it to the main circuit breadboard I had created that held the power supply, and soldered the wires from the earpiece board to larger, more secure pigtails that came off the main board.
I took the whole thing out to my motorcycle, wired it in as a test, turned it on, linked it to my cell phone, and tried it out. To my surprise, it worked perfectly, the very first time! When my cell phone rings, I hear a special ring tone over the bike intercom, and a second later, it picks up the call automatically. I can then hear the calling party over the bike intercom, and when I talk, they can hear me. To end the call, I press the button that I wired into the earpiece.
When the bike is first turned on, the Bluetooth module does not come on - so I can ride in peace if I want. However, if I need to be reachable, I can turn it on after the bike is on by holding the button down for three seconds. If I like, I can turn it off by doing the same thing again.
I'm thrilled! I'm going to get an enclosure for it tomorrow, then wire it permanently into the bike.
If anyone is interested in the circuit I designed, let me know and I'll draw it up and post it.
