2009 Star Trek Bluetooth Comunicator

This project wasn’t on my list; however one day I was board and got inspired. After doing some initial research I found that while other people had built a Bluetooth speakerphone into a Star Trek Communicator most were selling them for a hefty profit, and therefore not forthcoming with the process involved in there construction. This meant that I would have to figure everything out myself, not really a big issue however as that is half the fun.

Mark I

I began the project knowing that my research knowing that I would need 2 phases, the prototype (Mark I) and the final model (Mark II). Since this project would involve soldering micro circuitry (which id delicate at best) knowing this I decided to use the cheapest components I could find. This cost was mainly reflected in the cost of the Bluetooth headset that I would be using which was a Jabra 2040 and ran about 10 bucks at CompUSA. The only person to respond to my request for information about there build, would only say that they used an 8ohm speaker. This was a useful tip but not very helpful to the overall problem that I knew would arise; the fact of the matter was that simply attaching a bigger speaker to a low output connection would not make it louder; I would need an amplifier of some sort, initial I used the LM386 which has drawbacks including; too high a power requirement, poor audio quality, and it produces to much heat.

After I initially wired up the circuit a major issue became apparent, while the stock battery compartment provided enough power for the sound board or the Bluetooth board individually it could not power the amplifier which wanted at least 4V; let alone all 3 devices when I only had 3V available.

My initial solution was to rip apart old cell phone battery’s and wire them up since when stacked and wired in series they not only were about the same size as the original battery compartment but provided 7V of rechargeable power. Once this was wired up it worked amazingly well... until I had to recharge it and the battery’s overcharged, expanded, and became useless. This made me do some serious research work to find something that would fit in the tiny space available, as well as provide the power I required. Eventually I found a "J" Battery, which a 6V rechargeable cell is made up of 4 AAAA 1.5V battery’s in series; the cost was $10 dollars.

After purchasing the J Battery I cut off the battery compartment on the back cover of the communicator, and glued the battery door shut. Next I removed the case from the J Battery and soldered wires to it, then I wired in a barrel connector for recharging the battery, I set the barrel connector into the space that used to be used for the retention screw on the battery case. Finally I taped the 4 cells together before gluing them to the bottom of the case.

the last item I purchased was a singing greeting card, because I needed the thin 8ohm speaker inside it, the speaker inside the communicator was adequate however in the new location for the speaker; in the front of the case (pointed at the user, instead of the default location which was on the back of the case against your palm) the stock speaker was way to thick to allow for the battery and the Bluetooth board to fit behind it.

Finally I connected everything in parallel to the battery.

Now that I have discussed the power issues, I will go into how I integrated the 3 different circuits.

First off I disconnected the 2 buttons on the sound board, they activated functions that were just way too annoying to leave in place; and all I needed from the sound board was the chirping that it made when you opened to flip cover. I took one of the buttons and soldered leads to it, then glued it back onto the sound board in the same location, but making sure that the button terminals did not touch the soundboard terminals. Next I soldered those wires to the terminals for the multifunction button on the Bluetooth headset. Next I wired up the LM386 to power and the speaker. Then I wired the Bluetooth board and the soundboard in parallel to the LM386 IC. I removed one of the communicator’s buttons and installed the microphone from the headset in its location, the rubber grommet that housed the mic happened to be the same shape as the button.

After this the Mark I prototype was complete and ready for testing, I paired the headset with my phone (which was especially annoying because I couldn’t see the status led) then called my voicemail. the call had a bit of static but nothing too bad, my next call was to a friend who commented that there was a bit of an echo, and that I sounded like I was on a 2-way radio ( I just love irony). The test was successful, but the battery life was extremely limited and the sound quality needed serious improvement.

Mark II

For the MarkII my primary goal was to clean up the Rats nest of wires that the Mark I had been, while trying to simplify how the circuits interconnect. To accomplish this I re-purchased all of the components and got to work.

I used the back of the Mark I case since it was already modified with the 6V battery and recharge port, I also ordered the a TDA2822M amplifier IC, which is a better choice for an audio amplifier in my case, due to its output being allot more clear, as well as it not getting as hot.

Again soldering leads on the Bluetooth board has been one of the banes of my existence! However, I am quite proud of my self, because I managed to successfully solder leads to the battery terminals, multifunction button, speaker, mic, and most importantly the status LED! this meant that I could now wire the 2 white LED's from the sound board into the status LED from the Bluetooth; meaning that I now had everything I setout for! I cut the circuit pathways to the LED's on the sound board, and jumped the cut so the circuit would still be complete, then I soldered leads onto the LED's them selves and wired them in parallel to the leads from the Bluetooth board. Next I unsoldered the function buttons on the soundboard, jumped the connections to keep the circuit intact, and soldered the leads from the Bluetooth multifunction button to one of the activation buttons from the sound board, and then I glued it back to the board with goop, which is nonconductive so I would not have to worry about circuits getting crossed. Since this headset only has a multifunction button, the volume is controlled from the phone.

Once all of the connections were made on the sound board I fit the microphone into place, then I re-placed the sound board into the case, began the work of trimming wires where possible, and fitting everything into place so that the case would be able to close properly. After that, all I had left was to connect the TDA2822M amplifier IC to the Bluetooth, and then connect that circuit and the sound board to the speaker. after making the initial connection I was not impressed with the output level of the device and fearing that I had miss wired something re opened the case, while I was handling the active circuit the sound level kept jumping significantly louder, after a few minutes I found it was due to my hand shorting between pins 4, 8 on the IC which are bridged, and the negative terminal of the speaker. So after a quick application of solder and wire, the output was now at acceptable levels.

I closed the case, and made my first official call, the range on the BT communicator is about 25' I have considered making an antenna for it and running it around the flip cover (its supposed to be an antenna anyway) however I decided that this would be more trouble than its worth. The talk time on this is about 10-20 minutes, depending on how loud you have the output volume. The output is prone to having a bit of static, and I have had complaints of occasional echo, and every now and then sounding like I'm on a 2-way radio. However with its few flaws, the project performs wonderfully and I can say that I am amazed that I was able to fit everything into so small a case, especially considering the fact that it was never intended to accommodate all the extras I stuffed in there.

I would not recommend this project to anyone without good soldering skills, or the patients of a saint, ESPECIALY if you’re planning on using this exact case; however the "classic" communicator is much larger and would most likely accommodate everything comfortably. In retrospect, it might have been a more interesting project to integrate this with a micro 2-way radio rather than a BT headset.

This is my 2009 Bluetooth Communicator, it works well enough considering that it was build from a $15 toy and a $10 Bluetooth headset. It was a great project idea for a weekend that turned into a month long research project.