N A O D E C S C E N T C O N T R O L L E R Electronics Schematic · Rev 2.0 · 2026-05-19 12V PSU → 4× custom-firmware-driven ultrasonic atomizers (113 kHz piezo · JY-M27AO) via ESP32-S3-Relay-6CH 12V GND CH1 (GPIO1) CH2 (GPIO2) CH3 (GPIO41) CH4 (GPIO42) ⚠ JY-M27AO POWER: USE REAR SOLDER PADS ONLY (PH2.0, UNPOPULATED FROM FACTORY) 12V ON USB PORT = INSTANT BOARD DESTRUCTION ⚠ PSU1 DC PSU 12 V 5 A · DIN rail (5× margin over 1.0 A steady) V+ V− F_MAIN · 2A slow-blow → all F1 · 1A slow-blow → ESP ANT1 · 2.4 GHz SMA u.FL → SMA pigtail ANT CH1 · GPIO1 NC COM NO CH2 · GPIO2 NC COM NO CH3 · GPIO41 NC COM NO CH4 · GPIO42 NC COM NO CH5 NC COM NO CH6 NC COM NO + − DC 7–36V A+ B− GND RS485 DO NOT CONNECT GND pin U1 · ESP32-S3-RELAY-6CH WAVESHARE · CUSTOM FIRMWARE · 7–36 V VIN (12V) GND PSU+ ATZ1+ ATZ2+ ATZ3+ ATZ4+ F3 · T500mA A1 Atomizer Drv 12V · ~150 mA · 113 kHz V+ OUT+ OUT− GND Z1 113 kHz piezo F4 · T500mA A2 Atomizer Drv 12V · ~150 mA · 113 kHz V+ OUT+ OUT− GND Z2 113 kHz piezo F5 · T500mA A3 Atomizer Drv 12V · ~150 mA · 113 kHz V+ OUT+ OUT− GND Z3 113 kHz piezo F6 · T500mA A4 Atomizer Drv 12V · ~150 mA · 113 kHz V+ OUT+ OUT− GND Z4 113 kHz piezo ── COMMON GROUND BUS (STAR) ── ── +12V BUS ── BILL OF MATERIALS · 9 LINE ITEMS # QTY REF DESCRIPTION 1 1 U1 Waveshare ESP32-S3-Relay-6CH 2 1 ANT1 2.4 GHz SMA antenna, u.FL pigtail 3 4 A1–A4 JY-M27AO atomizer driver · 12 V rear pads · 6–24 V 4 4 Z1–Z4 113 kHz piezo transducer, microporous disc 5 1 PSU1 DC PSU 12 V · 5 A · DIN rail (5× margin over 1.0 A steady) 6 1 F_MAIN Inline fuse T2A · 2 A slow-blow · 5×20 mm 7 1 F1 Inline fuse T1A · 1 A slow-blow · 5×20 mm 8 4 F3–F6 Inline fuse T500mA · 500 mA slow-blow · 5×20 mm 9 6 — Inline fuse holder 5×20 mm (F_MAIN, F1, F3–F6) WIRE-GAUGE / AMPACITY CH AWG A · max RUN 18 ~1.0 A / 21 % PSU→F_MAIN 22 0.40 A / 43 % F1→ESP 18 ~0.6 A / 12 % F_MAIN→COM splice 22 ~0.15 A / 16 % splice→CHn.COM 22 ~0.15 A / 16 % CHn.NO→driver 22 ~0.15 A / 16 % A_n.GND return 18 ~1.0 A / 21 % GND trunk star All 12 V trunks 18 AWG; all sub-branches 22 AWG (all loads under 50 % ampacity) FUSE MARGIN (§4.6) FUSE SIZE LOAD RATING MARGIN F_MAIN · T2A 5×20 mm ~1.0 A 2.0 A 2.0× F1 · T1A 5×20 mm 0.40 A 1.0 A 2.5× F3–F6 · T500mA 5×20 mm ~0.15 A 0.25 A 3.3× All slow-blow. F3–F6 at T500 mA (3.3×) — selected for JY-M27AO inrush. T250 mA caused inrush trips on cold-start. T500 mA confirmed adequate. U1 · HARNESS (used) PIN NAME NET CH P1 VIN (12V) 12V_ESP 12V P2 GND GND GND CH1 COM (GPIO1) 12V_COM A1 CH1 NO SW_A1 A1 CH2 COM (GPIO2) 12V_COM A2 CH2 NO SW_A2 A2 CH3 COM (GPIO41) 12V_COM A3 CH3 NO SW_A3 A3 CH4 COM (GPIO42) 12V_COM A4 CH4 NO SW_A4 A4 A_n · ATOMIZER DRV (A1 shown) PIN NAME NET CH 1 V+ SW_A1 CH1 2 GND GND GND 3 OUT+ PIEZO_1+ CH1 4 OUT− PIEZO_1− CH1 NOTES 1. Fuse topology: F_MAIN (T2A) protects all downstream; F1 (T1A) only the ESP/relay-coil sub-branch; F3–F6 (T500mA) per-channel atomizer protection. T500 mA selected — handles cold-start inrush from JY-M27AO piezo driver. 2. 12 V relay COM: the four CHn.COM screw terminals are INDEPENDENT — not internally tied. Splice the post-F_MAIN 12 V trunk through a ferrule into four short pigtails, one per CH1.COM…CH4.COM. Do NOT rely solely on the daisy-chain jumper. 3. GND topology: single star bus. 18 AWG trunk from PSU to a screw-terminal block; 22 AWG spurs from each atomizer driver return to that same block. A1–A4 returns merge on a right-side collector before the trunk. 4. EMI hygiene: piezo drivers run at 113 kHz. Keep atomizer feed runs short (< 30 cm) and twist each 12V+ / GND pair to minimize loop area and 2.4 GHz coupling. 5. Custom firmware rule: relay GPIO switching rate must not exceed 1 Hz. Minimum ON-time ≥ 500 ms. Never auto-cycle channels faster than ~1 Hz — mechanical relays will not survive audio-rate switching. 6. Custom firmware init: ensure relay GPIOs (1, 2, 41, 42) start LOW on boot to prevent simultaneous channel firing on power-up. REVISION HISTORY Rev 1.0 · 2026-05-14 — Initial release. Corrected fuse topology (F_MAIN + F2 added); 18 AWG upsize on trunk runs. Rev 2.0 · 2026-05-19 — 5 V rail removed (U2, F2, RC1–RC4 deleted). COM bus 5 V→12 V. JY-M27AO rear-pad power. Custom firmware. F3–F6 T500 mA (inrush fix). Rear-pad warning added.
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