Description of LED / timer solution

A while ago I created a solution for my home to activate a LED light on the outside. The light will turn off when no movement has been detected during 2 minutes.

As I made this before the FabAcademy started I have asked chatGPT to summarize our conversations sofar.

✅ What You Built

You now have:

Manual start lighting system
Motion-extended runtime
Minimum on-time protection
Electrical isolation between sensor and microcontroller
Proper relay coil protection
Fused low-voltage side
DIN-rail professional mounting

🧾 Bill of Materials (BOM)

1️⃣ Control & Logic

Qty	Component	Notes
1	Arduino Nano (5V version)	Main controller
1	PC817 optocoupler (DIP-4)	Isolates PIR26 from Arduino
1	BC547 transistor	Drives Finder relay coil
1	1 kΩ resistor	Base resistor for BC547
1	1 kΩ resistor	Current limiting resistor for PC817 LED side
1	1N4007 diode	Flyback diode over Finder relay coil
1 (optional)	10 kΩ resistor	Base pull-down for BC547 (recommended)

2️⃣ Power Supply Section

Qty	Component	Notes
1	ORNO DIN-rail 230V → 12V DC power supply	Main low-voltage supply
1	GYVRM DC-DC converter 12V → 5V	Powers Arduino
1	T1A 250V slow-blow fuse	12V line protection
1 (optional)	T2A 250V slow-blow fuse	230V lamp protection

3️⃣ Switching Section (Mains Side)

Qty	Component	Notes
1	Finder 46.61.9.012.0040 relay	12V DC coil, 230V contact
1	Finder DIN-rail relay socket (97.xx series)	Mounting base for 46.61
—	230V LED outdoor lamp	Existing or new
—	Terminal blocks (DIN rail)	For L/N/PE distribution

4️⃣ Sensors & Inputs

Qty	Component	Notes
1	STBTech PIR26 motion sensor	12V powered, LED switching output
2	Momentary push buttons (NO)	Indoor & outdoor
—	Low-voltage wiring	For buttons and PIR

5️⃣ Mechanical & Mounting

Qty	Component	Notes
1	IP65 enclosure (Stegen)	Main control box
1	DIN rail (35 mm)	Inside enclosure
1	Small perfboard (prototype board)	For PC817 + BC547 circuit
1	DIN rail PCB mounting clip	Mount perfboard neatly
Several	WAGO connectors / terminal blocks	Wiring distribution
Several	Cable glands (IP68)**	Cable entry

6️⃣ Wiring

Use	Type
230V internal wiring	1.5 mm² solid or stranded
12V wiring	0.75 mm²
Signal wiring	0.25–0.5 mm²
Earth wiring	Green/yellow

🔌 System Architecture Summary

230V Side

230V → ORNO PSU
230V → Finder relay COM → NO → Lamp

12V Side

ORNO 12V → fuse → Finder coil + GYVRM + PIR26

5V Side

GYVRM → Arduino 5V

Signal Isolation

PIR26 LED output → 1k resistor → PC817
PC817 transistor → Arduino D4

Relay Drive

Arduino D8 → 1k → BC547 → Finder coil

⚡ Electrical Ratings Summary

Section	Voltage
Mains side	230V AC
Relay coil	12V DC
Arduino	5V DC
PIR26	12V DC

Absolutely — here is a clean, structured schematic diagram of your complete system.

I’ve separated it into logical blocks so it is readable and suitable for documentation.

📐 COMPLETE SCHEMATIC DIAGRAM

🔴 1) 230V MAINS SECTION

              230V AC INPUT
              ──────────────

   L (Brown) ── Fuse T2A ──────────────┬──────── ORNO L
                                        │
                                        │
                                   Finder Relay
                                   COM ──────┐
                                             │
                                   NO  ──────┴────── Lamp L

   N (Blue) ──────────────────────────────── ORNO N
                                              │
                                              └──────── Lamp N

   PE (Earth) ──────────────────────────────────────── Lamp PE

Only the phase (L) is switched by the Finder relay.

🟡 2) 12V POWER DISTRIBUTION

                ORNO 12V OUTPUT
                ───────────────

         +12V ── Fuse T1A ───────────────┬──── Finder Coil A1
                                          │
                                          ├──── GYVRM IN+
                                          │
                                          └──── PIR26 Vin+

         0V  ────────────────────────────┬──── GYVRM IN-
                                          ├──── PIR26 Vin-
                                          └──── System GND (common)

All low-voltage grounds are common.

🟢 3) 12V → 5V CONVERSION

                 GYVRM
            ┌────────────────┐
   IN+  ◄───┤ +12V           │
   IN-  ◄───┤ 0V             │
            │                │
   OUT+ ───►┤ 5V  ───────────┬── Arduino 5V
   OUT- ───►┤ GND ───────────┴── Arduino GND
            └────────────────┘

Arduino is powered directly from regulated 5V.

🔵 4) RELAY COIL DRIVE (BC547)

                     Finder Relay Coil
                     ──────────────────

          +12V (after fuse) ───────────── A1
                                           |
                                           |
                                           A2 ────────┐
                                                      |
                                                 Collector (C)
                                                BC547 Transistor
                                                      |
Arduino D8 ── 1kΩ ──► Base (B)                        |
                                                      |
                                           Emitter (E)
                                                      |
                                                     GND

Flyback Diode (1N4007)

Diode across A1–A2:

   Cathode (stripe) → A1 (+12V)
   Anode           → A2

🟣 5) PIR26 → PC817 ISOLATION

PIR26 Side (12V)

PIR26 LED+ ── 1kΩ ───► PC817 Pin 1 (Anode)
PIR26 LED- ───────────► PC817 Pin 2 (Cathode)

Arduino Side (5V, isolated)

PC817 Pin 3 (Emitter) ─────── GND

PC817 Pin 4 (Collector) ───── Arduino D4
                                │
                                └── INPUT_PULLUP enabled

When PIR triggers:

PC817 conducts
Arduino D4 reads LOW

🟤 6) PUSH BUTTONS

Inside Button:
Arduino D2 ──────┐
                  └── Button ─── GND

Outside Button:
Arduino D3 ──────┐
                  └── Button ─── GND

Both configured as:

pinMode(pin, INPUT_PULLUP);

Pressed = LOW

🔷 SYSTEM BLOCK OVERVIEW

  230V ── Finder Contact ── Lamp
        │
        └── ORNO 12V ── Fuse ──┬── Finder Coil (via BC547)
                                 ├── GYVRM 5V ── Arduino
                                 └── PIR26 ── PC817 ── Arduino D4

⚡ Electrical Separation Summary

Section	Voltage	Isolation
Mains	230V AC	Isolated by relay
Control Power	12V DC	Fused
Logic	5V DC	From GYVRM
PIR Signal	12V	Isolated by PC817

✅ What This Diagram Guarantees

No 12V ever reaches Arduino directly
No 230V reaches low voltage section
Relay coil protected
Low voltage fused
PIR fully isolated
Fail-safe: relay off at reset