Ulty Multy - EMG Level Detector

Ulty Multy - Dual 555 Timer with EMG-Controlled LED Blinker ================================================ Welcome to the documentation Ulty Multy - EMG! This project demonstrates how EMG-like signals can be simulated and used to control LED blinking behavior using two 555 timer circuits configured in monostable and astable modes. For detailed images and schematics, please visit the [GitHub Repo](https://github.com/mixuanpan/EMG_555Timer_Project). ## Foreword Electromyography (EMG) signal interpretation is fundamental in prosthetics and biointerfacing. This project introduces a proof-of-concept interface where muscle activation is simulated and used to control LEDs, illustrating the concept of brain-computer interaction using analog electronics. By integrating op-amps, dual 555 timers, and oscilloscope-based signal simulation, the system visually responds to simulated muscle contractions with LED pulses, representing signal strength. This project serves as a foundational prototype for EMG-based prosthetic control systems. --- ## Circuit Overview This system is based on two main subcircuits: 1. **Monostable 555 Timer** - Triggered by an EMG-like pulse - Generates a fixed-width pulse (e.g., 1.1 seconds) 2. **Astable 555 Timer** - Enabled only during the monostable pulse - Blinks LEDs at a fixed frequency **📷 Embed:** - `![555 Timer Block Diagram](image-url-here)` - `![Monostable Circuit Diagram](image-url-here)` - `![Monostable Timing Diagram](image-url-here)` - `![Astable Circuit Diagram](image-url-here)` - `![Astable Timing Diagram](image-url-here)` --- ## Oscilloscope-Based EMG Simulation To simulate EMG data without electrodes, a square wave was generated with the oscilloscope’s signal generator: - **Waveform**: Square - **Amplitude**: 0–2V - **Frequency**: 5 Hz - **Target**: LM324 op-amp’s non-inverting input **📷 Embed:** - `![EMG Oscilloscope Input](image-url-here)` --- ## Monostable Mode Testing - **Circuit Timing**: `T = 1.1 × R × C = 1.1 × 100kΩ × 10μF ≈ 1.1 s` - **Trigger Source**: LM324 comparator detecting signal threshold - **Measured Output**: 1.08–1.1 sec pulse **📷 Embed:** - `![Monostable Oscilloscope Screenshot](image-url-here)` --- ## Astable Mode Testing - **Formula**: `f ≈ 1.44 / ((R1 + 2×R2) × C)` `R1 = 10kΩ`, `R2 = 22kΩ`, `C = 10μF` → `f ≈ 2.91 Hz` - **Measured Frequency**: 2.85 Hz - **Duty Cycle**: 65%  --- ## Final Circuit Behavior The number of LED blinks corresponds to the EMG pulse strength: - **Weak signal** → 1 blink - **Strong signal** → 5–6 blinks **📷 Embed:** - `![2 LED Output Example](image-url-here)` - `![Full Circuit Schematic](image-url-here)` --- ## Conclusion - Dual 555 timer configuration successfully detects and visualizes EMG-like input - Oscilloscope simulation provides repeatable and tunable test signals - Simple analog electronics effectively simulate prosthetic control logic --- ## Future Improvements - Integrate real EMG electrodes and ADC interface - Use precision components to reduce drift - Add low-pass filtering before comparator stage --- ## References 1. [LM324 Op-Amp Overview](https://www.ariat-tech.com/blog/lm324-operational-amplifiers-pinouts,application-examples,size-packages,datasheets.html) 2. [LM555 Datasheet (TI)](https://arc.net/l/quote/lfnlvizb) 3. [LM741 Datasheet (TI)](https://arc.net/l/quote/nkdecbuu)