About this project

The purpose of this project is to lower or decrease the volume of a radio through a remote control with Arduino and to visualize the value on an LCD display. This project, "Remote-Vol," is a high-utility exploration into Infrared Signal Forensics and Legacy Hardware Retrofitting. It bypasses the need for internal circuitry modification by utilizing an external mechatronic bridge to bring wireless volume control to analog stereos.

If a button is pressed on an Arduino remote controller, the signal is received by an IR sensor and elaborated with Arduino Uno. When vol+ or vol- is held down, the Arduino will turn a servo on clockwise or counter-clockwise, which will turn volume knob of my stereo. The LCD display will show the volume percent and when the volume is more then 80% will reveal, "too high!”

Technical Deep-Dive

• IR Pulse-Width Decoding Forensics:
  • Protocol Identification: The system utilizes a TSOP-series receiver to demodulate incoming infrared bursts. The firmware employs the IRremote library to decode standardized protocols (NEC, Sony, RC5). Each remote button maps to a unique hexadecimal identifier, which is used as the trigger for the actuation logic.
  • Sampling Integrity: To prevent "False Triggers" from ambient light or secondary remotes, the code implements a signal-validation check, ensuring only verified hex-codes from the target controller are processed.
• Mechanical Coupling & Kinematics:
  • The Knob-to-Servo Bridge: Actuating a stiff stereo knob requires significant torque and precise axial alignment. The architecture utilizes an SG90 micro-servo paired with a custom mechanical coupling.
  • Angular Interpolation: The software maps the remote's VOL+ and VOL- commands to incremental angular shifts (e.g., 5-degree steps). This provides fine-grained control over the stereo's potentiometer without exceeding the physical stall-limits of the servo.
• HMI Telemetry & Safety Thresholds:
  • Inverse Percentage Mapping: The volume is displayed as a percentage (0-100%), calculated via linear interpolation of the servo's current angle.
  • Clipping Protection: To prevent hardware damage and auditory discomfort, the system features a software "Volume Ceiling" at 80%. If the user exceeds this threshold, the LCD triggers a "TOO HIGH!" warning, acting as a visual safety interlock.

The circuit

Arduino checks the servo motor through the pin11, the IR receiver with 10 and the LCD display through the pins from 2 to 7. Every component needs 5V except the pin 15 of the display, which uses maximun 4.2V and needs a resistence. The pin v0 (n°3) of the display connects to a potentiometer that regulates the brightness of the screen. The following scheme is made in Tinkercad.

The LCD display pins are connected with Arduino how in the code.

Engineering & Implementation

• Circuit Optimization:
  • The 16x2 LCD is integrated via a 5-wire parallel interface. Critical forensics are applied to the Backlight (Pin 15), which utilizes a 1k-ohm resistor to ensure current consumption remains within the Uno's 5V regulator overhead when concurrently driving the servo.
• Troubleshooting & Calibration:
  • The Contrast Node: A 10k potentiometer is used to calibrate the LCD's liquid-crystal bias (V0), ensuring the volume telemetry remains visible under various ambient lighting conditions.
  • Zero-Positioning: The firmware includes a calibration routine that centers the servo during initialization, aligning it with the stereo's "Mute" position for repeatable accuracy.

Conclusion

Remote-Vol showcases the power of Non-Invasive Mechatronic Design. By mastering IR Protocol Forensics and Angular-to-Volume Mapping, developers can bring modern wireless convenience to prestigious legacy audio systems without compromising their original analog integrity.

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Kinetic Audio: Controlling the analog world through digital forensics.