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Topic: ultrasounds to send and receive Morse code (Read 1 time) previous topic - next topic

kourpetis

i am trying to send some strings of characters via ultrasounds with Morse code. Since now i haven't get it to work ! I've tried lots of schematics on my bred board but since i don't have an oscillator to measure the out put signal and off course i can not hear a single thing i don't know if the are working or not.

does any one have any schematics that i can work on that could do the job for a transmitter and a receiver ?

thank you all for your time reading this

Far-seeker

I presume you are using an Arduino to generated the character strings, why not hook the reciever to the same Arduino and have it send any incoming characters to the serial monitor?

Grumpy_Mike

Put an LED (and resistor) across the ultrasonic transducer then you can see if it is working.

kourpetis

Far-seeker  this is what I do but I don't get a thing !
Grumpy_Mike this is a good idea ! Just to understand what you are saying
------o led o------o resistor o---------o transmitter o --------
right ?

Grumpy_Mike

No put the LED across, that is in parallel with the transmitter. That diagram showed a series connection.
You can even remove the transmitter and just have the LED.

kourpetis

one more thing ! Should I treat them like a normal speaker and a mike ? this is how that sounds right to my ears ! I want to sent Morse code through sound ( ultrasounds are sound too ) . Am I missing something here ?

kourpetis

ok ! so you mean I should of seen the light on and off ! you are right man ! thanks a lot !

Grumpy_Mike

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Should I treat them like a normal speaker

You can feed the transmitter with a 40KHz waveform for sustained output, or you can just kick them (Pulse) and they will ring at the resonant frequency. The receiver, yes just like a mike.

kourpetis

those 40 khz should I play with them through pwm or with electronics to create a driver that sends 40.000 hz to the transmitter ? and if yes do you know of any schematic that does something like that and it is compatible with arduino ?


Grumpy_Mike

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those 40 khz should I play with them through pwm

Yes I would.

The transmitter just replace the crystal oscillator circuit with the aduino.

The receiver looks fine.

kourpetis

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The transmitter just replace the crystal oscillator circuit with the aduino.


that's the 40khz in between the 2 capasitors 22 and 20 pf . right ?

Grumpy_Mike

Feed the arduino into pins 3 and 5 of U1, remove everything to the left of this.

kourpetis

First of all thank you very much for your quick responses.

correct me if I am wrong but I sent every thing from one pin on the arduino ( my output pin ), those are two should I just split that wire that is connected to arduino output pin and connect it to both pins ? am i missing something here ?

Grumpy_Mike

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those are two should I just split that wire that is connected to arduino output pin and connect it to both pins

Well i would take the wire to one pin and then another wire between the two pins. Splitting is not what you do. It matters not what order is goes in so long as all the three points are connected together.

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