This is an intriguing SW transmitter circuit or shortwave transmitter circuit tutorial, presented here in detail. Basically, the circuit is utilizing 12 MHz crystals to transmit the radio waves. Because of this 12 MHz crystal, the circuit won’t float its frequency. Thus, it broadcast its radio waves at exactly 12MHz.
Furthermore, The short wave or SW transmitter circuit operates in a shortwave HF band. Hence, it ranges from 3 MHz to 30 MHz only. Generally, it is utilized for short-range communication. But, in case you’re searching for the least expensive shortwave transmitter circuit. Thus, this DIY SW transmitter is demonstrated here for you!
Moreover, this SW transmitter is low power and entirely steady in operation. Also, it utilizes a 3 terminal ceramic resonator to set the radio frequency. Additionally, two signal-amplifying transistors 2N2904A and 2N3053 are also added up in the circuit schematic.
Hardware Components
The following components are required to make Shortwave Transmitter Circuit
| S.No | Components | Value | Qty |
|---|---|---|---|
| 1 | NPN Transistor | 2N2904A | 1 |
| 2 | NPN Transistor | 2N3053 | 1 |
| 3 | Ceramic Resonator | 12MHz Xtal | 1 |
| 4 | Speaker | 4Ω 2W | 1 |
| 5 | Antenna | – | 1 |
| 6 | Resistor | 4.7K, 100K, 22, 10K, 47K Ω | 1, 1, 1, 1, 1 |
| 7 | Capacitor | 0.01µF, 100µF | 1, 1 |
| 8 | Battery | 12V | 1 |
2N3053 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N3053
2N2904 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N2904
Shortwave Transmitter Circuit
Circuit Operation
Accordingly, the circuit is utilizing a 4-Ohms 2-watt speaker as a mouthpiece. This speaker changes the sound signals into electrical signals very effectively. Firstly, these sound signals amplify by a 2N2904A transistor. Therefore, after amplification, the signals regulate the carrier frequency. Which is acquired from the 2N3053 transistor. Additionally, the length of this transmitter is only 25 to 30 meters. Yet it can be additionally stretched out by expanding the radio wire length with appropriate matching.
Although this SW transmitter circuit can reach around 5 meters. However, you can build the range effectively with a basic RF enhancer and a low-pass channel arrangement.
Generally, you can’t simply interface a receiver to the sound input. That’s why this transmitter circuit needs an enhanced signal input. Therefore, it should be enough to modulate the amplitude of the radio waves.
The antenna plays the main role in the scope of this shortwave transmitter. Hence, without antennas, these signals won’t go more than one meter far. Moreover, the frequency can be changed a little (0.1-0.2 MHz). It can be done by including a capacitor in arrangement with the ceramic resonator.
Application
- SW transmitter radio is likewise utilized for very long-distance communication
- Shortwave radio is likewise utilized for broadcasting voice and music
- It is also utilized for military ‘Over-the-horizon’ radar
