Introduction: DIY RF Beacon
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What is RF Beacon?
An RF beacon is a wireless device that marks a fixed location and allows direction-finding equipment to locate it. It transmits a continuous or periodic radio signal with limited information content — for example, its identification or location — on a specified radio frequency, which is picked up by direction-finding systems on ships, aircraft, and vehicles to determine the location of the device. Occasionally, the beacon function is combined with some other transmission, like telemetry data or meteorological information.
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Step 1: Materials Required
- 1k ohm resistor (R5 R6 R7)
- 10K ohm resistor (R1 R3 R4 R8)
- 100K ohm resistor (R2)
- 10nF capacitor (C2 C3 C4)
- 10uf capacitor (C1)
- 2N3904 (Q1 Q2)
- 555 timer (IC1, IC2)
- RF module (433 MHz)
Step 2: Circuit Schematic
Step 3: Working
The RF beacon consists of three main units; A low frequency 555 oscillators, audio (high frequency) oscillator, and an RF 433MHz module.
The first unit, a low-frequency oscillator, creates a pulse at a frequency of approximately 1Hz which has an extremely large duty cycle (close to 99.9%). This signal is then inverted thanks to Q1 in the form of NOT gate, this creates a pulse with a duty cycle near 0.01%.
The low duty cycle pulse is connected to the RESET of an audio 555 oscillator. When the output from the low-frequency oscillator stage (after Q1) becomes 0V, the audio oscillator (IC2), is disabled and the result is no audio signal being produced. When the output of the low-frequency oscillator becomes VCC then the audio oscillator (IC2) is enabled and produces an audio able tone. This signal is inverted and then fed into the RF module which emits a tone on the 433MHz spectrum which can easily be picked up by receivers.
Step 4: Generating GERBER for PCB Fabrication
I have designed the schematic using KiCAD. Export GERBER files which have to be sent to the manufacturer in order to manufacture the PCB.
Step 5: PCB Fabrication
I have uploaded Gerber files to LIONCIRCUITS
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Okay, guys. I can share the Gerber files as well if anyone requires it. Feel free.