ULTRASONIC Listener

whit this ultrasonic listener receiver you will be able to hear sound that are too high frequency to be heard by human ears, such as glass breaking and electric arcing. this project will enable you to listen to a world of sound that few people even know exist.

The addition of a parabolic reflector further enhances the performance of this project. because ultrasonic frequency spectrum is beyond our hearing range, they can listened to only by indirect means, such as frequency heterodyning. frequency heterodyning is a method widely used in modern radio receiver.

in an ultrasonic receiver with frequency heterodyning, a local oscillator (LO) is used to generated square wave. the output of the LO is from 20 to 100KHz. the incoming signal (FI) is first pick up by an ultrasonic transducer and then amplified by a three stage amplifier. the input signal is then mix by a the mixer section to produce a sum (LO+FI) of the frequencies and a different of frequencies(LO-FI) at the mixer output. because the sum of frequency (LO+FI) is too high to be heard, it is filtered out. the difference of frequency (LO-FI) is just within the audio range of frequencies. therefore after amplification, it can be heard from a loudspeaker or headphones. a system block diagram is shown in figur 1.

Figure 1. Ultrasonic Listening Block Diagram

a special piezoelectric ultrasonic transducer acts as a microphone and it used to detect the high frequency ultrasound waves. whenever sound pressure is applied to the transducer, it will produce a small voltage at its output terminal. the frequency response of this transducer peaks around 40KHz but will work from 20 to 100KHZ. this weak signal from the transducer is passed to input pin 9 of the CD14069 integrated circuit (IC) at U1: a, a Hex inverter IC. this digital IC operates in the linear mode by connection feedback resistor R2,R3, and R5 from the inverters' output back to their inputs. the weak signal from the transducer goes through three stages of amplification at U1:d U2:e and U1:f the signal is then rectified and coupled to the mixer by C7. the schematic diagram of ultrasonic listener can be see at figure 2.

ultrasonic listener part list :

1. R1, R9 10K

2. R2,R3,R5 1 M

3. R4 100K

4. R6 470

5. R7,R8 470K

6. R10 10 ohm

7. VR1 10K

8. VR2 200K

9. D1,D2 1N4148

10. C1,C2,C7 0.01 uF 25V

11. C4,C11 20pF 25V

12. C5 200 uF

13. C6,C13 0.04uF

14. C3,C8, C9 0.022 uF

15. C10 100pF

16. C12 100uF

17. C14 10uF

18. C15 47uF

19. Cx 100pF

20. U1 CD4069 IC

21. U2 LM386 audio amplifier IC

22. Speaker 8ohm

23. BT 9V transistor radio battery

24. Y1 ultrasonic transducer 

APPLICATION

some application of ultrasonic listener

1. leaking glasses and rushing air

2. water from springklers or leaks

3. high voltage corona leakage, sparking devices, or light lightning

4. fires and chemical reaction 

5. Animal walking in wet grass

6. Pets moving in the dark

7. chattering insects and bats.

8. High frequency oscillators in computer monitors, TV sets.

9. mechanical bearings