Instructables
Make a simple AM transmitter that will cost you less than $5.
 
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Step 1: Stuff you need

A crystal whos frequency is between .9000 and 1.2000 MHz.
Some wire
A male headphone jack
A breadboard or experimental circuit board (optional)

Step 2: Wire it up

The crystal should have a little black dot on it. This is the only pin that we will not use on the crystal. We will connect the red wire of the headphone jack to the pin above the black dot. The white wire can also connect here if it is a stereo jack. We will connect the black wire or the ground to the pin to the right of the dot.

Step 3: Connect an antenna to it

Connect the last pin (the pin opposite of the dot) to an antenna. I used a really long telephone wire for my antenna (25 feet or so). I got it to play through my whole nieghborhood. Any sort of insulated wire will work for an antenna.

Step 4: Tune your radio

You now have to tune your radio to whatever your crystal says. The crystal will show the frequency in MHz and the radio will show it in KHz. If you used a 1.0000MHz crystal then you will tune your radio to 1000. 1.2000MHz crystal will give you 1200 on the radio and so on.

It may take a little time to find your station but it should work.

The louder you turn your music up, the louder it will be on your radio.

-I also found a better version of this. It uses a modulator. This improves the system a ton. Check out the second picture to see this with the modulator.
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mpetković16 months ago

You have a nice all explained how to make the radio transmitter on the site: https://www.youtube.com/watch?v=_4-Sx-T6VBc

gussmith0018 months ago

I build this and using an audio output transformer and it works great. Found a 1mhz crystal and audio output transformer on ebay.

Is the Modulator in the Drawing below that looks like a Transformer? How can we purchase one, and what do we look for?
The transformer is changing the voltage coming in from the mp3 player so the crystal can be "set off" a little easier. You need to kick it in the pants to get it vibrating.

The "modulation" (the signal) is being generated at the source (the mp3 player) and passed to the circuit so a carrier wave can be added.

If you don't use an mp3 player, but just just a voltage source, you have made a "CW" transmitter (for morse code).
bilsat11 months ago
Where i can find the crystal? I live in europe, and greece specifically. Please i want it to find it offline because i got no money for credit cards and i dont use paypal or anything that pays online.
stoobers bilsat10 months ago
Find a place that takes bitcoin.
nodoubtman2 years ago
I have a crystal of 1.8432 Mhz , is it okay?

thanks!
Any crystal will work. All you have to do is get the crystal of the frequency you want ;)
what does this circuit does in reality??

thank you! :)
marC:)
This circuit adds a 1mhz carrier wave to the electrical signal from the audio source.

The whole thing is then plopped onto the antenna and the antenna vibrates with those rf's (radio frequencies).

An AM medium wave radio near by can be tuned to "listen" to the vibrations.
Your username says nodoubtman but look you have a doubt!!! :P
ahhhh very good!!
1.8432 mhz is in the "shortwave" range.
AM radios are in the "mediumwave" range.
To receive the rf made by this crystal, you need an AM radio that receives in the shortwave range.
fenwaydog2 years ago
I'm using an old crystal will this still work? The problem is it doesn't have a MHz Rating anyware on it.
As long as you tune into the frequency that the crystal is transmitting, yes. Substitute any crystal value with the one listed and the results will work. Tuning the receiver to the same frequency as the transmitter is the only difference.
Can a receiver be made in a similar way?
Yes & No. A receiver to pick up the signal can be done, but sometimes it's a bit weak. It is much easier to make a receiver to tune into local radio stations. The Instructable that I used by MacDynamo is at... http://www.instructables.com/id/Simple-OP-Amp-radio/

I know you asked for a similar way, but the purpose of the crystal in this Instructable is to transmit at that frequency, the Instructable I linked is how to receive signals, so similar in function, not really. But simple in design and easy to build, absolutely. I hope this helps you. Additionally, there is a ton of videos on YouTube, most notably... http://www.youtube.com/watch?v=4E6uwEiOGsQ&feature=share&list=PLtv36f0AWivbNwZWXflk1OATeJlMk3B-P

There is also a follow up video with a schematic and partslist. (Although I noticed he hooked things up differently and sometimes the parts were different but nonetheless it works.) The simplest radio to use in my opinion would be the old school Crystal Radio or Foxhole Radio. Personally MacDynamo's Instructable is the easiest to follow and has the best results of the ones I tried. Enjoy!
eric m1 year ago
Hate the new layout for instructables. BRING BACK THUMBNAILS. So Stupid!
jcox241 year ago
I made a transmitter using an oscillator and an audio transformer, run off EITHER a 9v cell or usb
Evo71 year ago
Greattt............stuff in here!!!!
TuxedoRonny2 years ago
Hm... I did everything exactly as you stated (without using a modulator) and this didn't work- at all. I have all the exact components, tried several different radios, etc. and still nothing. Are you sure this works on its own? Has anyone else tried this?
electronicz2 years ago
I have a 1.00 MHz crystal like bmlbytes, how high of a voltage can this crystal withstand?
account3r22 years ago
if i make my own transmitters and receivers using a 50 MHz crystal, since the crystal isnt in the FM or AM range, would the FCC rules apply to it?
That is in the Amateur Radio range, and this circuit does not have enough power to really go far. Low power projects like this aren't enforced by the FCC, it's much like one of those mp3 audio devices that broadcast your mp3 player on a radio station in your car.

If you were to boost the power, you would then be subject to FCC rules.
nodoubtman2 years ago
do you need an audio transformer for this? i have a 600: 600 ohm 1 to 1

Thanks!
nodoubtman2 years ago
what kind of antenna do you use ?

thanks!
Just some wire shold do it.
Wesley6665 years ago
Also what if I want FM not AM?
get a 100MHz oscillator ...and tune your radio to 100MHz FM
so I would tune a radio to 33.3 FM if I had a 33.33 MHz oscillator. (The only oscillator I have is 33.33 MHz) Also how would you build a receiver for a specific Frequency? (Preferably 33.33 MHz!)
well first fm is from 87MHz to 108MHz what you have there is close to the range of remote controlled airplanes,49 i suppose you might be able to modify a radio to recive 33MHz (try by turning the little "screws" on the radio's circuit board?) also,since it is not in the am or FM range,you could broadcast it for MILES,ive hear of someone sending morse code from one side of the country to the other at 20something MHz
M0HIZ ReCreate2 years ago
Firstly, FM and AM and not bands of frequencies, they are types of modulation. Secondly, do not try to modified a radio to receive on a different frequency as you will almost certainly change the tuned circuits to something totally different to what you want. Finally, it is very common for people to talk to poele or send Morse code to people on different continents or the other side of the world. This is one of the many aspects of ham radio.
very cool. I found it in a computer motherboard or whatever and I tested it and it worked and I have never touched it since. I was hoping to build a receiver specifically for 33.33 MHz and I was wondering how I would go about that, and if it helps I have a crystal (two pins) with the same 33.33 MHz range if that helps. Thanks
if you find a crystal(2-legged) in a computer,it is used for timing,thats why replacing the crystal in a gameboy color speeds up the game. it speeds up the timing,making time trials unfair,crystals are used to keep track of time in computers,but oscillators...i have no clue why that would be inside a computer
crystals are a very important part of an oscillator, normally they are used in a oscillator circuit to set the frequency, and yea, the crystals on mobo are for timings, the 33.33 mhz crystal on the motherboard is to control the timings on pci slots, may pci cards also have 33mhz crystals on them,
this isn't a crystal its a oscillator, so it gives off a signal at that frequency, crystals don't give off signals, plus I have never seen a computer with another one in it ever and the computer it came out of had no 33.33 MHz crystals in it any how, they were all 14.6 MHz.
i assumed it was a crystal because he said 2 pin, never heard of a 2 pin ocillator. most new motherboards have digital oscillators so you can set the pci bus clock in the bios, so you might not see many crystals (if any) on new boards, im not sure what 14.6 mhz would time
well the computer it came out of was older then the dinosaurs but the frequency is 33.33 MHz and all the other crystals were 14.6 MHz so I have no idea what it was doing.
i still have my windows 3.1 computer up in my garage somewhere... it used to run DOS so im sure my computer has plenty of crystals
I have seen many crystals (two legged) in a computer but I have only ever had this one with an oscillator in it. Very unusual.........
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