Arduino Forum

Using Arduino => General Electronics => Topic started by: kourpetis on Oct 23, 2012, 03:01 pm

Title: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 03:01 pm
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
Title: Re: ultrasounds to send and receive Morse code
Post by: Far-seeker on Oct 23, 2012, 05:44 pm
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?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 23, 2012, 05:47 pm
Put an LED (and resistor) across the ultrasonic transducer then you can see if it is working.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 06:45 pm
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 ?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 23, 2012, 07:01 pm
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.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 07:03 pm
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 ?
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 07:04 pm
ok ! so you mean I should of seen the light on and off ! you are right man ! thanks a lot !
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 23, 2012, 07:06 pm
Quote
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.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 07:24 pm
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 ?
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 07:32 pm
http://discovercircuits.com/PDF-FILES/ULTRA40KHZXTR1.pdf (http://discovercircuits.com/PDF-FILES/ULTRA40KHZXTR1.pdf)
http://discovercircuits.com/PDF-FILES/40KULTRASOUNDRVR2.pdf (http://discovercircuits.com/PDF-FILES/40KULTRASOUNDRVR2.pdf)

do you think that they would work ?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 23, 2012, 08:02 pm
Quote
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.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 08:08 pm
Quote
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 ?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 23, 2012, 08:12 pm
Feed the arduino into pins 3 and 5 of U1, remove everything to the left of this.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 23, 2012, 09:01 pm
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 ?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 24, 2012, 12:01 am
Quote
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.
Title: Re: ultrasounds to send and receive Morse code
Post by: kourpetis on Oct 25, 2012, 12:23 am
OK ! finaly I moved from 0 ! NOW I GET VALUES TO MY SENSOR PIN !  :D !

the only problem is that they go from 340 to 370 up and down every 2 secconds gradualy ! is there a chance that is an echo or is it normal ?
Title: Re: ultrasounds to send and receive Morse code
Post by: Grumpy_Mike on Oct 25, 2012, 12:30 pm
Check to see you have the value of that coupling capacitor correct. The 0.1uF that goes between the trannsistor and the op amp. Making that 10uF or 100uF would do that to your signal.