Ever wanted to broadcast your own tunes or messages a short distance? This simple Micro Power AM Transmitter circuit, based on the design from Techlib.com, is a fantastic way to get started with radio electronics!
This compact circuit is designed for short-range transmission, perfect for experimenting or creating your own miniature broadcasting station. At its heart, it uses a few common transistors and passive components to generate a stable radio frequency and modulate it with your audio input.
The circuit features a crystal oscillator for precise frequency control, ensuring your signal stays clear. It also incorporates a variable capacitor, allowing you to fine-tune the transmission frequency within the AM band. Simply connect an audio source like an MP3 player or a microphone, and a small antenna, and you’re ready to transmit!
Key Features
- ✅ Crystal-controlled oscillator (1 to X MHz range) for accurate and stable carrier frequency
- ✅ 2N2222 differential amplifier for clean series modulation
- ✅ Modulation input from an audio source (MP3 player, phone, or microphone)
- ✅ Tank circuit (L1 and C12) with ferrite core transformer for efficient power transfer
- ✅ Complies with FCC Part 15 regulations (low power, up to 100 mW, 3-meter antenna)
The heart of the circuit is the 2N2222 transistor differential amplifier that provides clean series modulation. A crystal oscillator (1 to MHz) ensures frequency accuracy, while the output tank circuit (L1/C12) maximizes antenna current for better range.
The 1811 ferrite core inductor with center tap creates an auto transformer that boosts antenna voltage significantly. Proper tuning of this tank circuit is crucial – adjust C12 for maximum field strength reading. The circuit operates within FCC Part 15 regulations. It has power to 100 milliwatts with a maximum antenna length of 3 meters.
It’s a great project for beginners and a fun way to learn about the basics of amplitude modulation. So, gather your components, fire up your soldering iron, and get ready to enter the world of radio!
Disclaimer
Please be aware of and comply with local regulations regarding radio transmission power and frequencies. This circuit is intended for low-power, experimental use only.
More similar circuits
| Class C AM Transmitter |
| Simple series modulated AM QRP HF Transmitter |
| Simple two stage transistor one watt AM transmitter |
| Series Modulated AM Transmitter |