After Cosplaying a SWTOR Agent, I looked at more props I could create from the game.
I was always fascinated with the holoprojectors in the Star Wars films and the pocket holocom from the game appealed to me and seemed like an interesting project.
The proof-of-concept in the video below was put together with a black tinted resin body poured into a hand made modelling clay mould then filed and sanded into shape by hand. The electronics are based around and Arduino Pro Mini 3.3v using very small 8bit 8Khz audio samples squeezed into the programming memory. Due to the size of the components and the Arduino there was little room for a battery so I used a coin cell.
With the proof-of-concept proven, I set about designing a custom circuit. I wanted to keep the arduino compatability, but add power regulation, LiPo battery management and charging, an audio amplifier for better sound and additional flash storage for better quality audio files.
I designed the circuit around the same ATMEGA 328p microprocessor the Arduino uses, and added the additional components. This was a tough circuit to design on breadboard as it was just so complex. I did however get it to work and designed a PCB and had it professionally etched.
After building the new prototype I realised I’d reversed the USB connector and had to hack it in, but with that slight modification made, the holocom was working as I’d hoped. If you look really hard, you can see the fudge on the prototype board in the video below.
Something I hadn’t accounted for prior to the build was that I found the quiescent current drain (how much power it uses when it’s doing nothing) of my circuit was very high and I was concerned that the Holocom would drain its battery when not is use so. I had to set about incorporating a “suicide circuit”. This is where the microprocessor tells the power supply to turn everything off when it’s not in use. This reduces the power it uses when not in use to almost nothing. The problem then however is how to get power back to the microprocessor when you need it to work again.
This stalled me for a long time, but eventually I came up with a circuit that meant the power would go off when the device wasn’t in use and to power the device on again you just had to press and hold the “call” button for a second or two.
Having “perfected” the circuit, I had to fit the new components onto the PCB design, and this de-railed me yet again. 6 or more months went by before I revisited the Holocom and with a fresh perspective made the changes I needed. I plucked up the courage and sent the design to the PCB fabricator to get 12 sets printed.
Below if a video of the latest version of the hardware and firmware in a 3d printed enclosure. I do now have a “hero” version which has been painted in much the same way as my CD-33s and I do have around 8 more boards mostly assembled but needing a final check.
My single effort to create an aluminium body version have been a bit disheartening as I believe my CNC router isn’t quite up to the job. I do have one, but it lost steps along the way making it less than perfect.
My intention currently is to revisit the aluminium body, possibly after I move house as without a workshop routing aluminium is an awful mess.