Build a computer controlled radio transmitter

This will allow you to send morse code through radio waves to another computer. This could be used as a sort of chat program.

Step 1 Gather Supplies

You will need very few supplies:

-A crystal oscillator (will talk about which kind in the next step)
-A 9 pin serial jack (D-SUB9)
-A little bit of wire
-Something to use as an antenna
-A radio
-A male to male audio jack (unless you know morse code)

Comments

[bluescope93]

Gday,

Just a Question how do u send the Data to the Frequency Oscillator if all you are supplying to it is Power? , do you have a CW Key to turn the +9 Volts on and Off therefore creating a Morse Code Format?? , Or do u send the Audio for a Mono 3.5 or 6.5 Plug into a Radio or Computer and play a Tone or music??

Cheers and 73's
VK3FTIM
Tim

[Jasinqc]

Turning on and off the oscillator via the computer's DB (De) 9 port IS keying the oscillator. It can be unmodulated - - CW mode -- or modulated. In this case the computer program handles the selection and transmission of those modes.

Turning on the Carrier Wave - and then off - to form Morse code characters, is the very definition of CW mode.

Joe, N2QOJ

[4lifenerdfighter]

An idea I had: Have the computer output go into the mic input of a walkie talkie. Then, have the "Brother" Walkie talkie have headphone input into my friend's computer. Would this work? Also, for a different project, how could I change this program's source code to make it output on usb port instead of serial? I don't want to use an adapter; just change the source code.

[abamailinator]

would you please release the source code? i have no idea how to use various i/o ports on a system, and i dont want to sord through pages of dissasembly to find my answer.id love it if you would release the source :D

[bmlbytes]

I didn't write that program.

[KarateLover21]

Could you attach a microphone instead of the serial thing to send sound? I want to send sound around my town.

[nutsandbolts_64]

This reminds me of something. Oh yeah there was this other site that has the same pics and stuff. 

[kyle brinkerhoff]

just checked this out, i wonder how hard it would be to implement it with a arduino?

[nutsandbolts_64]

Oh, and uh does anyone know the legal limit of broadcasting signals from point A to point B in the Philippines? Otherwise, I'm making a pocket morse code transmitter!

[martzsam]

Will this program work with windows 7?

[qazxsw21000]

To those wanting to send audio (as in music/voice): You will need an audio transformer. The transformer has 5 leads: 3 on left, 2 on right. The 3 lead side: connect the audio jacks ground on bottom, input on top leaving the middle lead free. The right side: batteries + supply on bottom lead, the top lead connects to the oscillators input pin. What you used as the ground should be the same. Just plug it into the computers "audio out" plug. To transmit music, play it with whatever music player you like. Plug it into a mp3 player/ipod/cd player and take it with you where ever you go. To send voice, plug mic into pc "audio/mic/line in" plug.

[HOMEPIE64]

wait is it possible to use voice instead of morce code becuase you said something about a male to male audio jack and i would prefer using voice becuase morsecode is kind of hard to translate while typing for an ametuer

[qazxsw21000]

You would need an audio transformer. With the 3 lead side on the left, connect the jacks ground on bottom lead. Then connect the other jacks terminal on the top lead (the middle will not be used). On the right side (2 lead), connect the battery to the bottom lead then the top lead connects to the oscillators input pin. I believe that's how it went.

[radio.electronics]

I have a 4 pin 1.8432 Mhz oscillator.
Question 1). Can I decrease the frequency to within the AM broadcasting range?
Question 2).When Transmitting Morse code using the application mentioned in the article, if I set it to AM Low tone will it broadcast at half the frequency of 1.8432 Mhz.

Thanks
Radio Electronics

[brakeman75]

NOTICE!!! Anyone can listen to anything, but a F.C.C. LICENSE IS REQUIRED FOR TRANSMITTING ON AUTHORIZED FREQUENCIES. PLEASE consult the american Radio Relay League (ARRL) http://www.hello-radio.org/ for help getting started in this fascinating hobby. I don't want anyone to start on the wrong foot. Have fun!!
Brakeman75 a.k.a. KC2SXT, Tom

[bluescope93]

 Gday Tom

Totally agree with you there, i already hold my license and i have a 4 pin Crystal on 7.030MHz and did it all in the same format except where the antenna connects i used a SO239 Connector and used my Diamond CP6 HF Vertical QRP With AM and made a contact 523 KM's away 

I also was thinking of this project and thinking about the reflected power and what the SWR would be like 

Cheers 73's
VK3FTIM
Tim

[lazer155]

 How do I wire in the led?  I read on scitoys.com that it is some how connected to pin 7 on the serial port but it doesn't say which wire on the led goes to pin 7 and it doesnt say where the other wire goes.

[omnibot]

Pin 7 is prolly a signal output and therefore a positive output. Connect the LEDs long leg to ground and the short leg to pin 7.
I'm doing this off the top of my head so I might be wrong.

[owenaero]

very good way to practice the mores code good job

[joinaqd]

LOL. another guy made the same thing on another web site.

check out this website(its my second favorite website after instructables)
http://www.scitoys.com

[Win7Maniac]

Great project. Is there a program like this one that will send music out the serial port like a radio broadcast? Could you use a 1.0000mHz oscillator and tune a normal radio into 1000kHz and listen to the music? Thanks Ryan

[Buggy285]

Can you transmitt music and hear it on an am/fm radio?

[bmlbytes]

See my other instructable "Make a Simple AM Transmitter"

[kroq-gar78]

1. how would you receive a 24.3MHz signal with a radio? my pocket radio only goes up to ~1300KHz
2. my pocket radio is (# of MHz) * 100 , not (# of MHz) * 1000. I think that's how a lot of pocket radios are to save space

[Athlon]

I can't find this oscillators with 4 pins, only with 2 :S Help pls!

[kroq-gar78]

buy them at digikey.com click on oscillators, not crystals

[conrad2468]

EBAY!

[bmlbytes]

Look in old computers and desolder them. They will be found on cards that control things like serial ports, ethernet jacks, modems, etc.

[junits15]

ya but those are usually around 40 mhz

[locofocos]

They sell em in the catalog section of www.scitoys.com

[kroq-gar78]

is there any way to send music (or anything else) to the transmitter through the computer?

[rabiif]

be nice Why the expansion depends on the extent of transmission in the sender

[rabiif]

Why the expansion depends on the extent of transmission in the sender

[januz]

Is it possible to build a radio receiver in the same way as the transmitter?

[thenick678]

did you get this idea from scitoys.com

[WhiteTigerTails]

I wonder it you could use this to transmit voice between computers, or computer to a radio Reciever, such as a car radio!!!

[smitkenneth]

can the two pin oscillator work?anyone?

[FJSchrank]

Hi guys! The "2 pin oscillator" is actually just called a "crystal". It's just a chunk of quartz with attached wires. You must provide the external circuitry to make it oscillate. The "4 pin oscillator" used in this demonstration is referred to a "crystal oscillator" because it has both a built in crystal and a oscillator. A crystal oscillator is a crystal and oscillator circuitry in one convenient package. You simply apply power. So for this project, unless you modify it you cannot just drop-in a "2 pin crystal" without the added circuitry. Hope this helps! When I first learned about this stuff I too was confused. They should come up with more distinct names I suppose. -Fred Schrank

[pcfan]

I think http://www.peterevers.nl/Fotos/kristaloscillator.gif may work.
I'm gonna try it now.

[helpseeker]

what is male to male audio jack (unless you know morse code)