Passive three-channel LED carrier prototype for the Cylinder LED Controller: 35 ×120 mm target, six separate conductors to external 675–680 nm LED stars, downward optics and separate metal heat spreader in a 50 mm bore model-aircraft housing. Mechanical and daylight-visibility validation pending.
I’ve created the separate LED-carrier project and settled on a compact medium-beam lens candidate. I also found that the controller’s generic inductor footprints weren’t suitable for the power stages, so I’m replacing them with real power-inductor packages before placement.
Controller: the existing 47-component schematic remains the starting point. I identified unsuitable generic power-inductor footprints and started correcting them, but couldn’t verify the saved result.
LED carrier: I started its schematic and placement build; no completed result was available before execution stopped.
Optics: the provisional candidate is Carclo 10195, approximately 20 mm diameter × 9.9 mm high. Compatibility with your exact LEDs and daylight visibility at 150 ft remain unverified.
Neither PCB is confirmed placed, routed, or manufacturing-ready. Next work is to finish the inductor corrections, complete both placements, and check battery clearance and the separate metal LED heat-spreader arrangement before routing.
The LED-carrier build has now reported completion, but I couldn’t inspect its saved result, so I’m not yet confirming it as verified or manufacturing-ready. No additional project changes were made this turn.
Remaining work is to review the LED carrier, confirm the controller’s inductor corrections, and check battery, lens, and heatsink clearance before finishing layout and routing.
Prototype schematic and pre-layout brief for two long parallel PCBs inside a model-aircraft cylindrical body. The unit drives three retained 675–680 nm external star LEDs downward as a visual signal. It is not a certified aviation light, and visibility at 150 ft in direct daylight is a test objective rather than a promised performance.
Mechanical Envelope
Confirmed cylinder bore: 50 mm internal diameter, 25 mm radius.
Confirmed axial inside length: 127 mm.
Starting PCB envelopes: controller 35 mm transverse × 120 mm axial × 1.6 mm; LED carrier 35 mm transverse × 120 mm axial × 1.6 mm.
Controller: 4-layer standard FR-4, 1 oz copper, ordinary through vias as the starting profile.
LED carrier: 2-layer FR-4; it is an electrical carrier only, not the primary LED heatsink.
Proposed substrate center planes are y = +13 mm for the upper controller and y = -9 mm for the lower LED carrier. This asymmetric proposal reserves more outward depth below the LED carrier for optics and heat-spreader hardware. It is provisional and must be checked with actual bodies before placement.
Cross-Section Restrictions
The board center-plane separation is 22 mm. With 1.6 mm substrates, the facing surfaces are at y = +12.2 mm and y = -8.2 mm, leaving 20.4 mm between boards. A centered 17 mm-thick battery envelope then has only 3.4 mm total nominal clearance, about 1.7 mm each side, before wrapping, swelling, retention, insulation and tolerances. Therefore both inward board faces require a component-free battery pocket and no battery fit is approved until the actual pack is measured.
The upper board outer face is y = +13.8 mm. A 3.2 mm-high ESP32-C3-WROOM-02-class body would reach about y = +17.0 mm; the 50 mm bore chord there is about 36.7 mm, leaving only about 0.8 mm per side for a 35 mm board. The module dimensions used for planning (20 × 18 × 3.2 mm nominal) remain datasheet-extraction-unverified and must be confirmed during placement. Keep the antenna end at a board end and preserve its RF keepout.
Reserve a maximum 12 mm optical/thermal stack below the lower board outer face at each LED station. From y = -9.8 mm this reaches y = -21.8 mm. A centered 20 mm-diameter optic at that depth has a radial corner distance of about 24.0 mm, leaving about 1.0 mm ideal bore margin. This is feasible only for centered optics with no oversized holder or lateral offset; actual holders, star thickness, heat spreader, adhesive and tolerances can consume the margin.
The retained LEDGUHON JH-3535R12G42-T8B-675 is not listed in Carclo's compatibility data. A generic 3535 package match does not prove optical focus or beam angle. Treat 10195 as a mechanical/beam starting candidate only; bench-test beam profile, transmission and focal spacing with the actual 675–680 nm star before committing holders. Do not promise direct-daylight visibility.
Electrical Architecture
The existing schematic remains unchanged: externally balance-charged protected 3S input through XT30, fuse, disconnect and LTC4365/back-to-back MOSFET protection; TPS563201 3.3 V buck; ESP32-C3 control; three AL8860 channels; isolated LED-pair harness outputs. Each channel targets about 667 mA nominal from a 0.15 ohm sense resistor, remaining below the stated 700 mA LED operating point.
Interfaces
LED harness electrical order is fixed by the controller netlist: pin 1 LED1+, pin 2 LED1-, pin 3 LED2+, pin 4 LED2-, pin 5 LED3+, pin 6 LED3-.
The selected HX PZ2.54-1x6P WT project entry states 3 A, above 0.7 A/contact. Its exact mating-face pin-number orientation, locking/keying, mating housing, crimp terminal, wire gauge and body envelope remain unverified because the stored source is inaccessible. Retain it only as the established electrical footprint/placeholder until mating evidence is available; do not reverse the netlist order.
XT30UPB-M is a vertical two-pin PCB model. Its drawing includes 10.70, 10.20, 5.20 and 5.00 mm dimensions and two 1.60 mm holes, but the source does not provide a validated complete maximum body envelope or cable-bend envelope. Use an offboard XT30 pigtail/interface if body, mate and service clearance cannot be demonstrated in the bore.
LED Carrier and Thermal Architecture
The three existing 20 mm aluminum stars remain off-PCB and connect by short flying leads to three independent pad pairs near axial centers x = 20, 60 and 100 mm. No star pad, hole or fastener footprint may be invented. Each star needs a dedicated aluminum heat-spreader path mechanically independent of FR-4; do not claim the 2-layer carrier dissipates the LED heat.
Prototype thermal test limits: stop testing if any measured star/heatsink interface exceeds 80 °C, the FR-4 near an LED station exceeds 70 °C, or the LiPo surface exceeds 45 °C. These are conservative prototype stop limits, not component qualification ratings. Run one channel first, then all three for the 150-second session while logging temperature and current.
Application and Safety Limits
Intended signal points downward from a model aircraft toward a ground observer; it is not intended to illuminate a target.
Not a certified aviation, anti-collision or navigation light.
External 3S balance charging only. The RC pack is not assumed to contain a BMS; pack-level cutoff does not protect an individually weak cell.
Battery candidate remains a non-procured 48 × 17 × 17 mm envelope.
Layout Gate
This file and the LED-carrier floorplan are sufficient to begin board setup and placement, but not to assert final fit. Before routing, confirm actual battery dimensions, connector bodies/mates, inductor packages, switch access, optic/holder stack, star/heatsink hardware and bore tolerances. No fabrication or ordering is authorized by this checkpoint.
Controller footprint blocker: schematic inductors L1–L3 are specified as 47 µH, 1.2 A rated / 1.5 A saturation, and L4 as 2.2 µH, 4 A, but all four currently carry a generic 0603 footprint. Those current/inductance requirements are not credible in a normal 0603 power-inductor body. Select real shielded power inductors and update their footprints before controller placement; do not route or fabricate with the current generic 0603 assignments.