Ultrasonic Transducer 25kHz Audio Transmission Schematic With Electret Mic Receiver

How to transmit sound or music via ultrasonic transducer ( 25 khz transmitter)? I am going to use mic (electret) as a receiver. Can you provide me full schematic for transmitter as well as the receiver circuit? Please. Thank you.

What is the purpose behind this? Do you want to create a sort of wireless system but without the complexities of an RF transmitter/receiver?

IMO that would not work - at least not efficiently...and the distance between the transmitter and receiver would have to be rather small - almost to the extent of negating the purpose of this project.

You should look at a proper RF (FM transmit/receive) system for this.

There is many circuit in google. just search Mr 555

Hello.
Yes I can advice you the same points as Mr Rohit Dubla pointed to you - they have to be taken in mind so If you are sure of this unpractical project I can make the scheme and send you - it's just a PWM system - before I prepare it ensure your reqquest.

glad to here from you.

Just to be clear on this, are you trying to modulate an ultrasonic signal to carry audible sound in the same manner as AM radio modulation ?

Hell,
the best simple way must be Pulse Width modulation PWM - and I prefere this to you low cost and good results but there are other ways like PPM - pulse position modulation - and PCM Pulse Code Modulation - but in this filed of practicals we don't use AM modulation because it's the werst results and arround the same cost . do you want to go ahead? what type you prefer Digital System or Analog System - the second one is cheapper but more components.

I did something similar to this in the 1970s but I tried to use narrow band FM. I was very young at that time, but I could receive the signal up to a few inches only. I used old TV line oscillator transformers to make tuned circuits as the IF amplifier (actually TRF) receiver with a ratio detector. It was quite a large set up. opamps were not around at that time hence the LC amplifiers. If I were to do it again, and if I had time I likely would I would use band pass opamp filters, and maybe a PLL demodulator. I would also use a parabolic dish at each end. I think next time I may also use single side band suppressed carrier telephony instead of trying FM at such a low frequency. I reckon it may be possible to transmit perhaps a kilometer if done well with plenty of transmit power. One thing I will mention, which I am known for, and that is Dont Give UP. Use your detractors to spur you on even if it is just to prove them wrong. I do this all the time and it can be great fun and you can even make new discoveries as well. I once heard a scientist say that nano machines are impossible, whilst another was building them because he did not believe it was impossible!. Thus if you think it possible, then it very likely is.. Cheers from ans inspired fan.

Good exprements and no impossible at all may be very difficult but possible
1km ultra sonic takes a lot of power - and Tx transduser - how availabel is it ?
I think not more than 20 - 30 meter in flat area
So do you want to go ahead ?

regards

Now lets see . . . ultrasonic transmission . . . powered for one km range . . . thinks about that . . . hmmm.

Yes, we can definitely say that all dogs in the town will be driven absolutely mad.

OK I can guide you through what I think is possible. Firstly, conventional older radio receiver circuits should do the job for Rx. Firstly dynamic range is not likely to be a problem. Thus high performance mixers etc need not be used and this simplifies things considerably. So, where to start. In the receiver, a grounded base amplifier using a low noise transistor could be used ahead of the mixer. The mixer I suggest is one I have used before and is a Gilbert Cell type, made by NXP. It is an NE602, or SA602. It only needs a minimal local oscillator power, and its design (for direct conversion could be the same ass for the Tx oscillator. Actually you will need a pair of NE/SA602s driven with a quadrarure local oscillator. Following the mixer will need to be an audio quadrature phase shifter, which can be a poly-phase network or pair of op amps with an RC feedback network. The two audio paths are summed, and then fed to a high gain audio system with AGC. This would include an audio power amplifier to suit your needs.
The transmitter would be the reverse of this, but the power amp could be an off the shelf unit as it is only transmitting at around 25 kHz. You could go for 100 watts if you like. Being SSB, is economical on power as you ate only using the amplifiers output during speech. If all of this works, then you could add speech clipping, and increase the received signal to noise by about 9dB (from memory). This has inspired me to try it as well when I get the time. Well the path you need can be checked out with a pair of reflectors (parabolic) and a continuous 25kHz tone at one end and the front end amplifier with the receive transducer, and a lot of gain and an oscilloscope off the receiver. That will bea cheap (er) way to see f it can work. keep in mind the band wiidth needed as you may need to limit the bandwidth with a filter during the tests. As you can see some dedication s needed. I have been working here on a new receiver type for many years on and off and I still dont quite have it right yet, but each set of experimtnts improves performance a small amount and I am nearly there. So if you have what it takes, go for it. I will help along the way wher I can. Good luck(you always need some luck)

You're right

Why not use infrared instead? That could yield hifi soundquality if done properly.

IMO anything other than RF would be difficult. Transmitting binary over IR or ultrasound is much easier in that the modulation is simply ON/OFF. PWM might just work - but either ways the problem with ON/OFF signalling is suppression of harmonics generated due to the square wave nature of the carrier.

I could be wrong here but this is what I feel: The carrier has to be a pure sine wave in order for it to be more easily transmitted and received - even with digital communication the carrier is still sine wave...just that the carrier frequency is much higher than the sampling rate of the digital signal. Plus digital would need encoding (address & data) so that unintended recipients can be excluded.

For audio Tx/Rx (at least for DIY) AM or FM is ideal. IR would work PROVIDED we can modulate the frequency or amplitude of the IR emitter - with a typical IR LED either is cumbersome...modulating IR frequency (FM) would be much harder and modulating its amplitude (AM) might work but then there won't be much modulating index available (i.e., no signal to full signal modulation levels might not be much different).

Doing it with IR is much closer to doing it with RF, but RF becomes much simpler - maybe not in implementation but in terms of the fact that RF allows much easier modulation of either amplitude or frequency.

When using radio at 25 kHz, the antenna size is astronomical. I built a 22 kHz transmitter for only 5 watts CW and could not get high enough voltage capacitors to transmit with a 20 x 20 meter capacity top hat with base loading. I settled for about 100 mW. The only problem I had was that there was an RTTY high power sub marine station 1 MW from memory a couple of thousand Km away. After I was about 1/2 kM away from my transmitter that was the only station I could hear. I am assuming that ultrasonic comms is to be used because it is not done much. (if at all). I think that there could be many discoveries made by going the way of Ultrasonic communication. Perhaps that is enough reason to do it, because it is a nifty challenge.