Essaie

🔦 IR Interruption Detector PCB

This project is a complete PCB-based system that detects interruptions between an IR emitter and receiver. When an object blocks the IR beam:

• A buzzer/speaker is triggered,
• A 7-segment display counter is incremented,
• A reset button clears the count.

The circuit is entirely based on discrete components, including NE555 timers, CD40106, and a CD4033 counter/decoder. It also includes a robust regulated power supply, and can be used in security, object-counting, or automation systems.

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📷 Schematic

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🧩 PCB Layout

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🧱 3D Model

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⚙️ System Overview

➤ Power Supply

The power input is 230V AC, stepped down using a transformer and rectified via a bridge diode. The output is regulated to +12V DC using a 7812 voltage regulator.

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➤ IR Transmitter Stage

• Components: 2x NE555 + TSAL4400 IR LED
• The first NE555 generates a square wave (~38 kHz), modulated by the second NE555 to create an amplitude-modulated IR beam.
• Transistor Q1 amplifies the signal and drives the IR LED with enough current.

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➤ IR Receiver & Detection

• TSOP2254 is used to receive the modulated IR beam.
• Its digital output goes LOW when it detects the 38 kHz signal.
• When an interruption occurs (e.g. hand/object blocks the beam), the output goes HIGH, triggering further stages.

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➤ Signal Conditioning & Alarm Logic

• NE555 (U6) is configured in a monostable mode.
• CD40106 Schmitt triggers (U2, U3) are used for clean signal shaping and logic handling.
• This ensures only valid interruptions trigger the output.

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➤ Output Stage

• A speaker or buzzer (AST-1732MR-R) is triggered via transistor Q3.
• An LED also indicates the alarm visually.

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➤ Counting Stage

• A CD4033B 7-segment BCD counter increments with each IR interruption.
• A D168K display shows the count.
• A reset button allows clearing the count manually.

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🔁 Workflow Summary

1. Idle: IR signal is received, no object interrupting.
2. Interrupt: Object breaks the beam → TSOP output goes HIGH.
3. Detection: NE555 monostable timer triggers.
4. Alarm: Buzzer sounds + 7segments Display increments count.
5. Reset: Pressing the reset button clears the counter.

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🧰 Bill of Materials (BOM)

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🔧 Tools Used

• KiCad 9 for schematic and PCB design
• Open source components
• **Through-hole components **

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🧠 Author

Designed by Bejaoui Hamza
Date: 18 June 2025
Project name: IR Interruption Detector

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📂 License

This project is open-source under the MIT License.

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