Build a Compact IR Transmitter Circuit Using LM3909 and a 1.5V Power Source

schema October 25, 2011
🔧 How to Build a Simple IR Transmitter Circuit Using LM3909 and 1.5V Power
IR Transmitter Circuit Using LM3909

If you're into DIY electronics, this infrared (IR) transmitter circuit is a must-try. It's compact, green, and operates on a unmarried 1.5V battery, making it best for low-electricity or transportable initiatives.

The coronary heart of the circuit is the LM3909, a versatile LED flasher IC. While it is usually used for blinking LEDs, on this setup it's cleverly repurposed to generate a excessive-frequency infrared signal.

⚙️ Why Use LM3909 for IR Transmission?

The LM3909 allows you to build a full IR transmitter circuit without complex timing components or microcontrollers. It acts as an oscillator, producing pulses that drive an infrared LED, allowing it to emit modulated IR light suitable for remote...

With just two passive components (C1 and R1), you can control the output frequency of the signal. Lower values of these components result in higher frequency output—ideal for syncing with standard IR receivers or remotes.

🔋 1.5V Power Supply: Efficient & Portable

One of the coolest features of this circuit is its low voltage requirement. A single 1.5V AA or AAA cell is enough to drive the whole setup. That means:

  • No need for voltage regulators.

  • Great for compact gadgets or DIY remote systems.

  • Safe for beginners.

🔄 Adjusting the Flash Rate and Signal Frequency

By experimenting with the R1 resistor and C1 capacitor, you may tweak the frequency of the IR pulses. This helps you to personalize the circuit for numerous IR-managed gadgets or communication protocols.

Example Values:

  • C1 = 10µF

  • R1 = 1kΩ → Increase R1 to slow down the frequency; decrease it for faster flashing.

🧰 Components Required

  • 1 × LM3909 IC

  • 1 × Infrared LED (IR LED)

  • 1 × Resistor (R1, e.g., 1k–10kΩ)

  • 1 × Capacitor (C1, e.g., 10µF–100µF)

  • 1 × AA battery holder (1.5V)

  • Breadboard or PCB for testing

🌐 Applications

This type of IR circuit is ideal for:

  • DIY remote controls

  • IR beacons for robots

  • Short-range wireless communication

  • Triggering IR receivers in automation systems

  • Learning basic oscillator circuits

📈 SEO Keywords Included:

  • IR transmitter circuit

  • LM3909 LED flasher IC

  • Infrared signal generator

  • 1.5V IR emitter

  • IR remote control DIY

  • IR modulation with LM3909

  • High-frequency IR circuit

  • Infrared transmitter using 1.5V

  • DIY electronics project

schema

Posted by schema