If you do something, for fucks sake…
…do it properly.
A few days earlier:
Unusual are the cases where a standalone IP68 button can be installed in a very compact electronic device. Even if the Nixie-CAM (NC from now on) is for personal use and I could just get away with having to unscrew things and a little bit of impracticality regarding storage and actuation, I kinda preferred, to make it look store-bought. Any product that has removable pieces or accesses, is usually accompanied with some sort of soft cover or rubber button pad. Of course you can create an o-ring sealed shaft to actuate an internal tact switch, but that’s rarely practical and comes with it’s own problems.
And that’s the ulterior motive for experimenting with PVC ink, as mentioned previously. Definitely was not for keychains XD.
Picking up the 3D models for the μSD cover and buttons, I built a pair of 3D moulds around them to be machined out of aluminium.
They would also be the first time I would be doing parts that needed locating pins between them. Not that it’s complicated, but first times are always scary (AND the fact that I had no spare stock for the pieces didn’t help easing my mind. XD)
First I did the buttons. Having seen that a ball endmill would push material rather than snagg it on the first keychain test (where I missmeasured the thickness of the stock), I was somewhat confident I would get away with pushing my luck with aluminium deformation for the domes, wich measured 2.98mm in 3mm stock . If you look closely, one of the domes tops is a bit wrinkly, but for an experiment, that was good enough.
Since the pushbutton recess male part had to protrude from the top mold, I decided to simply cut much more area than needed and then cut around (crossing the pin locations so it would still align)
Liberally apply plastisol grease:
Press:
And apply 150ºC for 90 seconds at least (you can apply more time if needed), then enjoy the results. Note how the central rib prevents the left button from moving when depressing the right one.
Next, the mould for the uSD card cover. I made a slight change between the original and the test, because I had not yet received the 0,2mm engraving bits (In case you nottice the difference between the original 3D model and the final piece.
The recess in the top half was so the final thickness of the piece would not interfere with the internals had I made it all the way stock thick.
Assembled. At least this time I didn’t forgot to invert the text so it would read properly ^^U
By the time I had made this, I had PVC ink solvent, with wich I thought I could make the rubber a lot more liquid without changing properties too much, but unfortunately that was not the case, and for the PVC ink to be liquid, it has to be specially formulated. In any case, using a syringe and some vacuum, all the molds should be easily fillable with the material I already have.
I kinda forgot to set up the stepover at 0,05mm, so you can see the individual passes of the ball endmill. The letters look fine because I did a special engraving pass, not just relying on just the horizontal passes.
I did remember to do it for the top half, and the results show as a very smooth surface that will seal properly against the case (it’s made to have an interference fit, so it’s always snug)
Live:
With that taken care of, next step was to put the pcb buttons in place. However, at this point, I just discovered that the video board ALSO had a power shutoff circuit included, wich had rendered the circuitry in the pcb unnecesary. I also had mismeasured the board thickness and got a 1.6mm, wich didn’t leave much height to actually glue the rubber buttons…
NOT that that was going to deter me, tho!
I just soldered the REC/STOP button cables and attached those to the internal pushbutton, so they would have a better grip than just soldering on pads alone. After that, I attached all the circuits and batteries, and did a small 24 minutes recording test to see if anything exploded:
Luckily, nothing did, but I noted that the converter board did get hot, as did the main heatsink. With that in mind I assembled the camera to see if there would be space to add a small aluminium board to help dissipate the heat from the converter into a larger area (and in the process protect the li-po battery from focalized intense heat).
Yeah, I definitely could fit something in there. (yes, I was very careful about using steel tweezers around powered electronics).
Some hacksaw time and a bit of vice bending later (without the bend the video board AND cables would not fit):
And…it was about time to close the thing!
The translucent body of the camera will definitely NOT allow for covert recording:
I won’t cover the magnetic connection in the back of the camera because it’s exactly the same than the F9 I did before.
And with that…the V1.0 of the camera is finished!
Testing.
Since I lack a proper thermometer (or FLIR camera) I decided not to risk yet a full zero airflow thermal test before I can get at least some footage recorded (nothing would infuriate me more than just not being able to test the camera in the helmet).Remember I did a 24 minute test but all the pieces where outside the enclosed camera space, so that was just a best case scenario on dissipative cooling.
What I did have to do however, was a full test with at least a bit of air (in the end this is a motorbike helmet camera, it will have airflow over it most of the time anyways. It just was not very scientific due to the lack of instrumentation.
I picked up my vertical home fan and put the camera to record the highest airflow setting for 1h straight. after such time, the heatsink was hot to touch, but I could rest my hand on it indefinitely, so I reduced the airflow to the setting number 2 for another half an hour, with more or less the same skin-test result. I further reduced the airflow to 1 and left the camera for another half an hour (for a total of 2h of continuous recording) and by that point, the heatsink was too hot to continuous touch, BUT not insta-burn your skin.
Note: Ambient temp was 27-28ºC
After this, I thought about seeing how the drone world heatsinked the main processor, only to shockingly discover they just don’t…
I agree that a drone in flight will get some airflow, but at the same time, they sandwich the video card with other controller and video transmitter boards, so it’s not like it has the best cooling situation…
So any heatsinking is definitely better than no heatsinking I would say.
By the time I was writing this post, I didn’t have proper double sided 3M foam tape, so I just attached the camera with random tape to have a glance at how it finally fit:
Yeah, I agree the piss colored body doesn’t help much, but I’ll take care of that later.
I haven’t removed the old mount yet, but that I’ll do as soon as I get the proper mounting foam for the camera.
Definitely not switching to a GoPro now…
Nope…
The best thing is that, within reason, I don’t have to worry anymore about the camera orientation, I can just tilt and twist the gimball to the proper position.
Smol test at the balcony. Color looks a bit saturated, maybe I can change some firmware for that, but then again, this is desert-like sun, so…
Performance.
Daylight:
After testing, this camera performs slightly better than a Sena Prism Tube, wich would be a direct competitor of sorts.
Light management is better, not being overwhelmed by bright lights as much as the sena. As soon as the bright spot occupies enough part of the field of vision, the Nixie-CAM (CADDX Turtle V2) starts compensating, instead of waiting longer for a very sharp change in light.
(sound warning!)
I must say, even at 1080p/60fps on youtube, the original video looks better.
Night time:
1.- City Led Lights:
2.- Sodium Vapour street lights:
3.- Entering a less illuminated city road:
4.- Roadside pole lights only:
5.- Absolute darkness (No road lighting, LOW beams):
6.- Absolute darkness (No road lighting, HIGH beams):
7.- Non illuminated highway, no other cars:
8.- Non illuminated highway, being overtaken by a car:
Analysis:
Pros:
- Infinitely better than a 20$ F9 tube camera.
- About 2/3rds the price of a Sena Prism Tube, with slightly better performance on mine.
- Much more streamlined than any other existing cameras at price range.
- “Infinite” battery capacity until max record time (minimum should be 4.5h at 1080p/60fps to 64Gb, but storage usage varies wildly so it’s hard to calculate. μSD cards are cheap tho.
- My fucking own design.
Cons:
- Heat management is difficult. The camera requires good airflow, but I’m not sure final operating temperature WITH the heatsink will kill the board, I’ll be testing that soon.
- Piss color body (hey, it was cheap…).
- If you want to count it, not being removable from the helmet (but that’s how I want it, so…)
- Sound at speed is awful? (maybe can be fixed in post, maybe something can be done about the mic)
Veredict:
Was this worth it? ABSOLUTELY!
So much in fact, I’ll start working on a V1.5 camera to make it even better. Of course this is not a Go-Pro or any other generic action camera and it will never be. This is an extremely specific motorbike helmet camera that works (and relies) on riding conditions.
See ya!
P.S. Want one? Yeah, I’ll build one for you for 400€. Fucking expensive? Do you expect me to work for free or what…
The Electronic Mercenary 