Today is exactly one month since my last foray into this Project. The 0.8mm circuit boards from JLCPCB has long arrived. And just today, so were the special red 2835 (not 3528) SMD LEDs with a dome lens.
Version 002:
The board design at this time anchored on the choice of the 4 Red LEDs, which were the 3528 SMDs.
Version 004C:
I changed the design to receive 4mm (yes, 4mm) through-hole LEDs. At this point, I am still not sure on the final LED decision. If the 4mm LEDs has a square top instead of a bulbous end, my problems would be solved. If I use a SMD, I would have to have laser-cut a set of red acrylic lens to cover the holes. Actually, I still can, by sanding the 4mm LEDs to the right height where they can then also be used to lock the PCB onto the pack. As for the four 1/8W resistors they would also serve as distance so I do not have to sand down the LEDs too much.
Version 005B:
Ah, screw this, I am still undecided to whether use more elbow grease or spend more money to cover the four LED holes.
Version 002:
I am not sure why I was thinking of using the larger PIC16F628ASO and also, the 8-channel Darlington ULN2803. They took up a lot of real estate for just a simple LED sequence. Those Blue LEDs would need a current limiting resistor each too, which forced me to use those 0603 network arrays.
Version 004C:
Once I sobered up, I decided to drive each LEDs directly from the chip and so, the PIC16F628SS came into play. It is much smaller (but has finer pins) and gives me back more space. So, if you compare the two chips’s solder pads (from left and middle), you would realise the tremendous amount of space reclaimed.
Version 005B:
This is the latest version so far. There is not much difference except that I have merged both the SMD and 4mm through-hole solder pads together. Plus, some space for a JST1.25mm connector where, I hope, the LiPo batteries I needed would come with those connector sizes.
Which LEDs?
Pulling the Brakes…
By now, I can say that the Project has gone to the point of no return. Why do I say that?
This is because the PCBs for both the Cyclotron and also, the Power Cell has been made. And their dimensions were taken from dih01’s 3D file in Thingiverse which is the hollowed out version from TheNewHobbyist ( as seen on Tested). And, this is where I did something stupid; I compared it with gbfans’s plans, re-converted those numbers to 1/6th scale. So, the 3D pack is just a tad smaller and going into the 1/7th scale.
Looking at the image below, if you look carefully on the right, there are to numbers; 2.497mm and 4.244mm. The 2.497mm is the thickness of the Cyclotron front wall, from its inside right to the exterior of the lens window. The 4.244mm is the aperture of the four Cyclotron windows which, if I *ahem* drill/ widen the hole to 5mm, then the 5mm flat top LEDs would fit. By going this path, I now have to deal with the issue of the 5mm LED’s height which is about 5.3mm
Let’s round up some numbers for easier calculation. The 2.477mm thickness of the Cyclotron front wall is now 2.5mm. Take that away from the 5mm LED’s height of 5.3mm, I now have an excess of 2.8mm height to remove. Taking into consideration that the 1/8Watt resistors have a diameter of 2.0mm, I would still have 0.8mm to remove. In other words,
Height of 5mm LED: ~5.3mm
Minus Cyclotron Wall: ~2.5mm
Minus 1/8W resistors: ~2.0mm
Remaining gap to remove: ~0.8mm
The 3mm LEDs which height of 4.5mm was already perfect. It’s just too bad about the diameter and even if I thickened it with some plastic tubes or tape, it would look very weird.
Prototypes being prototypes, I guess there is still more work to be done, which is, if I wanted to, magnetise the shell, 3D print the Alice frame and motherboard (ie the back cover) in metal, find a tailor who will be willing to sew the olive drab straps and whatnots, plus, create a rub-on transfer for all the labels. Not forgetting all those wires, ribbon cables and hoses. And that is, assuming I am not going to re-scale every component of the original 3D file…
Or, another easier option is, I can just leave it as it is…
20260530 The 5mm LEDs
The 5mm LEDs came about 9 days. And you know what? It worked. This means, I have wasted more (than a year?) mulling about which LED to use and get (now irrelevant) obsessive pursuit of the 4mm LEDs although that was ideal. So, I just dgaf with the prototype and widened the Cycloton lens windows to 5mm, inserted the new LEDs and it does look good. The 4mm holes would be ideal but, let’s look at this objectively; if I am making a few, hand sanding the bulbous 4mm LEDs are too much work and the results has to be consistent. The other alternative would be to custom order LEDs but man, those costs a fortune…
