The RF beacon consists of three main units;

, an audio (high frequency) oscillator, and an RF

. 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 a 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.