PL-SENS-OPTIC-V3.0
Rev 3.0
✔ Production Verified
Executive Summary & Ambient Light Rejection
Interactive obstacle arenas, ninja tag courses, and ball pits suffer from extreme optical interference: high-power party strobe lights, moving laser projectors, direct sunlight through venue skylights, and fluorescent tubes. Standard continuous-wave DC phototransistors frequently saturate and produce false game triggers.
The PL-SENS-OPTIC-V3.0 employs a synchronous 38.0 kHz modulated carrier architecture with a 940nm infrared emitter and a matched transimpedance receiver circuit. It achieves an ultra-low latency response time of < 380 microseconds with 0.00% false triggers, capable of capturing high-velocity ball impacts up to 45 mph across beam gaps from 50mm to 3,000mm.
Circuit Theory & Signal Demodulation
- Emitter Stage: A precision 38 kHz 10% duty-cycle oscillator pulses a Vishay TSAL6400 high-power 940nm IR diode with 150mA peak drive current.
- Receiver Preamplifier: An optical PIN photodiode (BPW34) is coupled to a high-speed JFET transimpedance amplifier (OPA354) with a dedicated PCB guard ring suppressing picoamp surface leakage.
- Bandpass & Sallen-Key Demodulator: A 2nd-order active bandpass filter centered at 38 kHz rejects 50Hz/100Hz mains flicker, feeding a precision peak detector and high-speed Schmitt trigger (LM393).
Hardware Pinout & Signal Mapping
| Pin # | Net Name | Type | MCU GPIO | Signal Description |
|---|---|---|---|---|
| 1 | VCC | Power | — | 5V to 24V DC Regulated System Power |
| 2 | GND | Ground | — | Common Ground Return |
| 3 | OUT_N | Output | — | Active LOW Open-Collector Trigger Output (30V / 100mA max) |
| 4 | CAL_EN | Input | — | Logic HIGH activates self-test & optical calibration routine |