[GSMacLean]

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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.

 

[snickers104]

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Yes please, can I have a drawing?

Thanks.

 

[Sprdtyf350]

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I would be interested also..

 

[RayandTracy]

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this is just a sample of the great things you and others offer here:bowing::bowing::bowing:

Thanks for sharing your skills with all of us:action:

Ride Safe, Ray:waving:

 

[GSMacLean]

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I spent the afternoon wiring this into my bike and testing it. Unfortunately I have absolutely no pictures of any of this, because my wife took our camera to a wedding this weekend.

I mounted the circuit into a plastic box, put two pots on the top to adjust transmit and receive audio levels, and a DB9 connector, to make it easy to wire in and disconnect should I want to.

I mounted a small momentary pushbutton and a blue LED in the fairing of the bike, right above the left pocket. When the bike is turned on, I push this button and hold it down until the blue light turns on. At that time, I hear tones over the intercom from the Bluetooth module to let me know it's turned on, and at the same time, it connects to my phone. From that point forward, it will answer calls.

When my phone rings, I hear a musical tone over the intercom, and about a second later, it answers the phone, and I am connected to the caller. Anything I say into my microphone, the caller hears, and vice versa.

To hang up, I press the button on the fairing, or it will disconnect automatically if the caller hangs up.

I can similarly dial out by taking my phone out and dialing, and as soon as it connects, the call is routed to my helmet.

Because of the way it is wired, if I have music playing on the radio, the caller will hear the music. No easy way around that, I just have to remember to turn it down/off. That said, if either I or the caller speak, it mutes the music anyway, so it's not that big of a deal.

So I have done what I set out to do...with one caveat.

When the bike is running, there is a LOT of alternator noise - so much so that if the engine is running at more than about 3,000 RPM, the caller cannot hear me over the noise. I know it's the stator/rectifier, because if I disconnect the stator while the engine is running, the noise disappears.

I'm going to put a choke on the power supply input (I've included that choke on the schematic), but I also plan to get my scope out and confirm that the noise is actually making it past the caps and regulator in my circuit (which I was surprised at). If it is, then I'll have to find another way of killing it. If it is not, then I've got a problem with grounds somewhere, and that will be a bit more tricky to solve.

The Bluetooth module utilizes the system ground for the mic's ground, but NOT for the speaker ground, so I had to isolate the speaker output (both signal and ground) with capacitors in order to protect the audio finals of the Bluetooth module. If there is noise being injected due to a floating ground, I'm suspecting this is where it is happening. If this is the case, I may have to swap those caps for a coil or something.

In any case, it's working well enough, but I'll let you know what improvements I come up with as I work on it.

 

[Bagmaster]

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When you get a finalized design, I'd like to know if you would be interested in building the kits for sale. With my bad hands there's no way I could do such fine soldering.

Maybe you and Rudy ought to get together and design some things that can be patented and sold.

 

[GSMacLean]

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Bagmaster wrote:

When you get a finalized design, I'd like to know if you would be interested in building the kits for sale. With my bad hands there's no way I could do such fine soldering.

Maybe you and Rudy ought to get together and design some things that can be patented and sold.

There's really no way I'd want to build that kind of thing on a regular basis. Doing surface mount rework is extremely difficult, and takes hours of work - and a lot of times, you end up destroying what you're working on. As an example, in order to connect my new blue LED to the circuit board, I had to first desolder the LED that was on there - and it was about 1mm x .75 mm in size. Then I had to take two extremely fine wires, and solder them to the two pads left on the circuit board after I had removed the LED. I couldn't do it without the microscope. I'll do it for a one-off project of my own, but I sure wouldn't want to do it for a living!

On a tangent, when I had my TimeTrax company, the modules we had manufactured in China were all surface mount stuff, and we commonly modified production units to create new prototypes. We had a woman who was hired by one of the design firms we used, and her job was surface mount rework - it's all she did, and she worked for many high tech firms in the area. She could do things that were just amazing - for us, she tack soldered 40 tiny wires onto a QFP40 format chip - this is a chip with 40 pins on all 4 sides, and the pins were 0.4mm apart. Think of 40 tiny wires, tack soldered by hand into a space about 16mm long (just a little less than an inch), with no shorts. Just incredible.

If I were to build that kind of thing as a kit or whatever, I'd want to use an off-the-shelf Bluetooth module of some kind. I'll look around and see what I can find.

 

[snickers104]

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TimeTrax?? Are the guy that started TimeTrax like the XM recording TimeTrax?? I bought one of your units if that is the case and used it for a long time.

 

[GSMacLean]

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snickers104 wrote:

TimeTrax?? Are the guy that started TimeTrax like the XM recording TimeTrax?? I bought one of your units if that is the case and used it for a long time.

Yup, that was me. I wrote the software and designed the hardware.

http://www.timetraxtech.com/RecentPress/nyt.pdf

http://www.timetraxtech.com/RecentPress/orbitcast2.pdf


In any case, I found a supplier of OEM Bluetooth modules that could be designed into a circuit. The modules are around $60, the board another $5 or so, regulators and ancillary circuitry probably another $10, enclosure and connectors, maybe another $5-$10. So total cost would be around $80 to manufacture - now that's just a wild guess after looking at a couple data sheets, so I could be wrong. Assembly, marketing, etc. would be on top of that - I'm just talking cost of parts.

That unit also has A2DP capability, so you could play music on your phone, and it would pipe it (in stereo) into your helmet, via Bluetooth, in addition to the regular phone functions.

Now...the question is, does anyone think there would be a market for this sort of thing?

More importantly, if you saw a product that would allow you to talk on your phone over your Goldwing helmet headset/microphone as I described, as well as play music from your iPhone or whatever, what would you be willing to pay for such a device?

 

[snickers104]

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Cardo makes that exact thing and they are getting around $250 for two of them. I think that is a little pricey for myself but I guess they are selling them for that. Except they dont use the intercom system on the bike.

BTW the TimeTrax idea was VERY cool and I really liked it (so did my kids). I cant believe I get to talk to the guy that invented it!!! (NEAT!!)

 

[GSMacLean]

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snickers104 wrote:

Cardo makes that exact thing and they are getting around $250 for two of them. I think that is a little pricey for myself but I guess they are selling them for that. Except they dont use the intercom system on the bike.

BTW the TimeTrax idea was VERY cool and I really liked it (so did my kids). I cant believe I get to talk to the guy that invented it!!! (NEAT!!)

I see Cardo makes intercoms...but I don't see an "add-on" Bluetooth module that hooks into the existing Goldwing intercom.

You want to know the best part of TimeTrax? It was sitting in the hotel room in Vegas before CES (two years in a row), leafing through page after page of "spokesmodels", deciding which ones of them were going to be our "booth babes" for our booth at the show that year.

OK, maybe not the BEST part, but it was a great part.

 

[GSMacLean]

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OK, I had a couple hours this afternoon to pull things apart and chase down the source of the noise. Turns out the ground I was using to power the circuit was pulled from the accessory terminal - and there is 15 OHMS difference between it and the ground used by the intercom/component terminal. That's a HUGE amount when it comes to line-level audio, and was the source of the noise.

I took the ground I was using and connected it to the component terminal case. Once I did this, the difference between the ground in my Bluetooth circuit and the ground in the intercom was 0.1 ohms. Much better. This eliminated the alternator whine noise.

I was left with a new noise, however: a high pitched buzz, that was being injected into the intercom's microphone circuit, coming out of the "earphone" circuit of the Bluetooth module. I got my scope out and discovered that it was actually coming from the ground as well - but this time it was originating from the Bluetooth module, as its digital transmitter operated.

While the Bluetooth module's microphone shared its ground with the power supply, the "earphone out" of the Bluetooth module did not - it was a floating ground. However, the Goldwing shares a common ground between its microphone and headphone circuits. Because of this, I had decoupled the Bluetooth "earphone out" ground from the main circuit ground with a capacitor. This wasn't good enough - it allowed the module to inject the transmitter noise into the microphone.

I instead removed the decoupling capacitors and replaced them with a small 1:1 audio transformer that I had sitting around. As soon as I did this, the transmitter noise disappeared.

I'm quite happy with the result, the sound is loud and clear, and the calling party can hear me quite clearly as well.

Here's the modified circuit as it stands now:

 

[GSMacLean]

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After two long rides this weekend, I think I'm going to isolate the Bluetooth mic input with a transformer as well, as it is still picking up some noise (while the noise from the Bluetooth module into the intercom is completely gone). I'll let everyone know how it works when I find some time to do it!

 

[Oregonwinger]

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GS

I did this awhile back with an HS820 Moto headset, but, it doesn't like losing it's "battery power". It was locking up, and the only way I could get it to unlock was to hook the oem charger to it, then go thru the process again. I saw your link here about the Jabra, and decided to try the Jabra. I have it working on the bench perfectly, minus the hook-ups for the bike. With this Jabra, I can disconnect (same as switching off key) the batt + feed a multitude of times, and it always recovers, after the mf button cycle. A plus, indeed. I might just wire it up to always hot. It draws very little current.

And, was that external led fun !!! :shock::shock::shock::shock: I don't have the surfact mount gear you have, so I had to do it the old way. I managed to get the 2 approx. #40 wires soldered to the led, then captured the wires to the board with a piece of heat shrink. So, the original led is still in place. I filed the iron tip to a needle point, and, with a jewelers eyepiece on my left glass frame (10X), I got good results. I hope the 2 led's operating in unison don't take out the led driver. I think that little drive is probably good for 50> ma. The led I added is 20 ma, and I assumed the original led is about the same.

The switch was much easier, but still, a tiny job. I used the same tiny wires. Also, I noticed that this Jabra has no volume up/down.


2 Questions.

Where did you set the 2 pots?? I assumed you started out about 50%

And, what box did you use? I have been using a R. Shack box, but, it's not waterproof. I run it upside down, and the button is at one end, on the downhill side.

Thank for any insight.

 

[siebo]

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very interested in any info that is good and works.

 

[GSMacLean]

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Yup, that little Jabra seems rock solid - in fact, it seems to interoperate better with my phone (Treo 755P) than any other Bluetooth headset/speakerphone that I have ever tried. It comes up perfectly every time, and connects reliably.

As for the LED - I desoldered the LED on the board (if you look closely, it has an SMD resistor in series with it, right next to it on the board) and wired it into this Radio Shack LED. I had measured what the Jabra was putting out under load, and it fell into what that Rat Shack LED seemed to use, so I tried it - and it worked fine.

You could take a small knife and pop the transparent top off of the SMD LED - that will destroy it, and eliminate any draw it is pulling off the driver, so you've got only the one LED remaining.

Once I had successfully tack soldered the wires onto the circuit board, I took a hot glue gun and gobbed it on there, to make sure they were not going to move - because it wouldn't take much!

I bought a Radio Shack box, mounted the two pots onto its lid, and then I mounted a DB9 male header that I had in my PC junk box - it was on a PC slot header, and was designed to plug into the motherboard, and provide a serial port on the outside of the PC. I removed the DB9 header from the PC slot header, cut out a hole in the Radio Shack box lid, and mounted the DB9 jack onto the lid. I then took all the wires coming out of the DB9 jack and soldered them to the various parts - audio in, audio out, power, ground, switch, and LED.

I then took a DB9 serial cable, cut the female end off, stripped back the wires, and wired them into the bike. I drilled two holes into the bike fairing, and mounted a momentary switch as well as the blue LED.

To install it, I just remove the left turn signal, plug the DB9 onto the box, and stuff the box into the fairing through the turn signal hole, then reinstall the turn signal. It lets me easily disconnect the "guts" of it so I can take it downstairs and work on it instead of standing in the garage next to the bike.

I started the pots at 50%, but I found that the input (from the bluetooth to the intercom mic) ended up at very near 100%. The output (from the intercom headset to the bluetooth mic) I ended up at around 90% - any more and the thing pics up (what I assume is) RF noise from the Bluetooth unit and feeds it into the outgoing signal.

I just tonight put a second transformer in it - replacing the isolating cap on the bluetooth microphone input. I haven't had a chance to see how it affects the noise reduction, I'll find out tomorrow when I ride into work.

 

[Oregonwinger]

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I'm using the same led as you acquired, but, I might use the rectangular version instead. I filed the end at a 45 degree angle because of box placement on the bike. I'm not hiding the box, because of where the radiators are. Too hot. So it'll sit on top of left cubby hole's hard cover, aimed downhill. I'm installing the diode and the switch on the lower end, because of water problems. So, hopefully, with the 45 degree angle, I can still "read" the diode.

Also, I'm running the box upside down, to hopefully help with theft and water problems.

That noise you hear may be the voltage dbbler for the led. Since it's 1.5 power input, and the led runs at almost 3v. (With the 2 leds, anyway)

Will let you know how it works out. I may be a few days getting to the rest of it, as many things to do have cropped up all of a sudden.

 

[GSMacLean]

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You're right, it could be the voltage doubler - sounds like about the right frequency. However you can hear it (if turned up enough) whenever the module is powered and linked. I don't know about you, but if I were designing the thing, I would run the voltage doubler only when the LED was on, to save battery power.

I wonder if it is simply processor noise from the module? If I cared enough, I'd put the scope on it to get the frequency, then design a narrow notch filter at that frequency to knock it out. If it's a digital source however, there's going to be a ton of harmonics that that wouldn't kill. Oh well - it's almost inaudible when the pots are adjusted correctly.

 

[GSMacLean]

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Oh, and I didn't get the opportunity to test it on my ride to work this morning, because my wife forgot to call me to test it out!!

 

[Oregonwinger]

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Good points.

Do you still feel the 1 meg pot is about right, or would you maybe prefer a 500k next go around?