Ultrasonic-receiver

The 4046 PLL is utilized as the core component of a tunable ultrasonic receiver designed for detecting inaudible ultrasonic sounds. This receiver can also function in conjunction with a simple ultrasonic generator to transmit and receive Morse code. The incoming ultrasonic signal is detected by the piezo speaker SPKR1, which is subsequently amplified by transistors Q1 and Q2. The amplified output is directed to the phase comparator input of U1 at pin 14. The chip's interval voltage-controlled oscillator (VCO) is adjusted by varying the potentiometer R9. If a 20 kHz signal is received by SPKR1 and the VCO is calibrated to generate a 19 kHz signal, the difference output at pin 2 will yield a 1 kHz signal. This signal is further amplified by Q3 and transmitted through transformer T1 to a pair of headphones. Should the received frequency rise to 22 kHz, a 3 kHz tone will be audible in the headphones. With the specified values for components C1, R1, and R9, the VCO can be tuned from 12 kHz to over 42 kHz, adequately covering the frequency range responsive to the piezo sensor.

The 4046 Phase-Locked Loop (PLL) is an integrated circuit that combines a phase comparator, a voltage-controlled oscillator (VCO), and a frequency divider, making it well-suited for applications requiring frequency synthesis and modulation. In this ultrasonic receiver setup, the PLL serves as a critical component that enables the detection of ultrasonic frequencies, which are beyond the range of human hearing. The piezo speaker SPKR1 acts as a transducer, converting the incoming ultrasonic sound waves into electrical signals. The transistors Q1 and Q2 amplify these signals to a sufficient level for processing.

The phase comparator within the 4046 compares the phase of the incoming signal from SPKR1 with the VCO output. The VCO's frequency can be tuned by adjusting the potentiometer R9, allowing for the precise matching of frequencies. The output from the phase comparator at pin 2 provides a difference frequency signal, which is indicative of the frequency deviation from the VCO setting. This signal can be amplified further by Q3, ensuring that it is strong enough to drive the headphones.

Transformer T1 plays a crucial role in coupling the amplified signal to the headphones, allowing the user to hear the modulated tones corresponding to the detected ultrasonic frequencies. As the frequency of the incoming ultrasonic signal varies, the difference frequency output changes accordingly, producing audible tones that represent these variations. The tunable nature of the VCO, facilitated by the component values specified for C1, R1, and R9, ensures that a wide range of ultrasonic frequencies can be effectively monitored, making this circuit versatile for various ultrasonic detection applications.The 4046 PPL is used as the heart of a tunable ultrasonic receiver that can be used to locate unheard ultrasonic sounds. The receiver might also be used, along with a simple ultrasonic generator, to send and receive Morse code.

The incoming ultrasonic signal is picked up by piezo speaker SPKR1, and amplified by transistors Q1 and Q2. The output is fed to the phase comparator input of U1 at pin 14. Tile chip"s interval VCO is tuned by turning potentiometer R9. If a 20-kHz signal is picked up by SPKR1 and the VCO is tuned to produce a 19-kHz signal the difference output at pin 2 will be 1 kHz. That 1-kHz signal is amplified by Q3 and coupled through Tl to a pair of headphones. If the received frequency increases to 22kHz, a 3-kHz tone is heard in the headphones. With the values given in the parts list for C1, R1, and R9, the VCO can be tuned from 12 to well over 42kHz, which should cover just about anything the piezo sensor can respond to.

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